Journal articles on the topic '7B chromosome'
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1
Kim, N. S., K. C. Armstrong, G. Fedak, K. Ho, and N. I. Park. "A microsatellite sequence from the rice blast fungus (Magnaporthe grisea) distinguishes between the centromeres of Hordeum vulgare and H. bulbosum in hybrid plants." Genome 45, no. 1 (February 1, 2002): 165–74. http://dx.doi.org/10.1139/g01-129.
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A TC/AG-repeat microsatellite sequence derived from the rice blast fungus (Magnaporthe grisea) hybridized to all of the centromeres of Hordeum vulgare chromosomes, but hybridized faintly or not at all to the chromosomes of Hordeum bulbosum. Using this H. vulgare centromere-specific probe, the chromosomes of four F1 hybrids between H. vulgare and H. bulbosum were analyzed. The chromosome constitution in the root tips of the hybrids was mosaic, i.e., 7 (7v, H. vulgare) and 14 (7v + 7b H. bulbosum), or 14 (7v + 7b) and 27 (14v + 13b), or 7 (7v), 14 (7v + 7b), and 27 (14v + 13b). The 27-chromosome tetraploid hybrid cells were revealed to have the NOR (nucleolus organizer region) bearing chromosome of H. bulbosum in a hemizygous state, which might indicate some role for this chromosome in the chromosome instability of the hybrid condition. The chromosomal distribution showed that the chromosomes of H. vulgare were concentric and chromosomes of H. bulbosum were peripheral in the mitotic squash. This non-random chromosome distribution and the centromere-specific repeated DNA differences in the two species were discussed in relation to H. bulbosum chromosome elimination. Meiotic chromosome analyses revealed a high frequency of homoeologous chromosome pairing in early prophase. However, this chromosome pairing did not persist until later meiotic stages and many univalents and chromosome fragments resulted. These were revealed to be H. bulbosum by fluorescence in situ hybridization (FISH) analysis with the H. vulgare centromere-specific probe. Because the chromosome segregation of H. vulgare and H. bulbosum chromosomes at anaphase I of meiosis was random, the possibility for obtaining chromosome substitution lines in diploid barley from the diploid hybrid was discussed.Key words: Hordeum vulgare, Hordeum bulbosum, centromere-specific repeated DNA, FISH, chromosome instability.
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Konzak, C. F., and L. R. Joppa. "The inheritance and chromosomal location of a gene for chocolate chaff in durum wheat." Genome 30, no. 2 (April 1, 1988): 229–33. http://dx.doi.org/10.1139/g88-039.
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The durum wheat (Triticum turgidum L. var. durum) cultivar 'Vic' was treated with the chemical mutagen N-methyl-N′-nitrosourea and among the M2 progeny a mutant with "chocolate chaff" (designated cc) was identified. Genetic analyses indicated that chocolate chaff is due to a single recessive gene mutation. The penetrance of the gene for chocolate chaff was environmentally influenced and varied from dark blotches on the glumes to complete coloration of culms as well as spikes. To determine the chromosomal location of the gene, the mutant was crossed with a set of 'Langdon' durum disomic substitution lines in which each of the 14 A- and B-genome chromosomes of durum wheat were replaced by their respective D-genome homoeologues. The segregation of cc was normal in all of the crosses except for those with the 7D(7A) and 7D(7B) lines. Cytogenetic analysis indicated that the gene was located on chromosome 7B, and that chromosome 7D has a gene that prevents the expression of cc when present in one or more copies. It was shown that the 'Langdon' D-genome disomic substitution lines can be used to determine the chromosomal location of genes in tetraploid wheat.Key words: Triticum turgidum, aneuploid, chromosome substitution, monosomic, cytogenetics.
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Dogramac1-Altuntepe, M., and P. P. Jauhar. "Production of durum wheat substitution haploids from durum × maize crosses and their cytological characterization." Genome 44, no. 1 (February 1, 2001): 137–42. http://dx.doi.org/10.1139/g00-102.
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The objective of this study was to investigate the effect of individual durum wheat (Triticum turgidum L.) chromosomes on crossability with maize (Zea mays L.) and to cytologically characterize the haploids recovered. Fourteen 'Langdon' (LDN) D-genome disomic substitution lines, a LDN Ph mutant (Ph1b ph1b), and normal 'Langdon' were pollinated with maize pollen. After pollination, hormonal treatment was given daily for up to 14 days. Haploid embryos were obtained from all lines and were aseptically cultured. From a total of 55 358 pollinated florets, 895 embryos were obtained. Only 14 of the embryos germinated and developed into healthy plants. Different substitution lines showed varying degrees of success. The most successful was the substitution 5D(5B) for both embryo formation and haploid plantlet production. These results indicate that the substitution of 5D for 5B confers on durum wheat a greater ability to produce haploids. Fluorescent genomic in situ hybridization (GISH) showed that the substitution haploids consisted of 7 A-genome chromosomes, 6 B-genome chromosomes, and 1 D-genome chromosome. Triticum urartu Tum. genomic DNA was efficient in probing the 7 A-genome chromosomes, although the D-genome chromosome also showed intermediate hybridization. This shows a close affinity between the A genome and D genome. We also elucidated the evolutionary translocation involving the chromosomes 4A and 7B that occurred at the time of evolution of durum wheat. We found that the distal segment translocated from chromosome 7B constitutes about 24% of the long arm of 4A.Key words: cyclic translocation 4A·5A·7B, crossability, disomic substitution, fluorescent genomic in situ hybridization (GISH), Triticum turgidum.
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Miller, T. E., S. M. Reader, and C. C. Ainsworth. "A chromosome of Hordeum chilense homoeologous to group 7 of wheat." Canadian Journal of Genetics and Cytology 27, no. 1 (February 1, 1985): 101–4. http://dx.doi.org/10.1139/g85-016.
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Individual substitution lines have been produced with Hordeum chilense chromosome A substituted in turn for chromosome 7A, 7B, or 7D of Triticum aestivum. Telocentric substitutions with the α arm, substituted for chromosome 7A or 7D, or the β arm substituted for chromosome 7B have also been produced. The substitutions have been confirmed by the presence of a purple straw marker, by gel isoelectric focusing of α-amylase isozymes, and cytologically using telocentric chromosome markers. Chromosome A has consequently been designated 7Hch.Key words: Hordeum chilense, wheat, chromosome substitution, homoeology, α-amylase.
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Ikawa, T., A. Kakegawa, T. Nagano, H. Ando, Y. Yamakoshi, T. Tanabe, J. P. Simmer, C. C. Hu, M. Fukae, and S. Oida. "Porcine Amelogenin is Expressed from the X and Y Chromosomes." Journal of Dental Research 84, no. 2 (February 2005): 144–48. http://dx.doi.org/10.1177/154405910508400207.
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Amelogenin is the major enamel matrix component in developing teeth. In eutherian mammals, amelogenin is expressed from the X chromosome only, or from both the X and Y chromosomes. Two classes of porcine amelogenin cDNA clones have been characterized, but the chromosomal localization of the gene(s) encoding them is unknown. To determine if there are sex-based differences in the expression of porcine amelogenin, we paired PCR primers for exons 1a, 1b, 7a, and 7b, and amplified enamel organ-derived cDNA separately from porcine males and females. The results show that exons 1a/2a and 7a are always together and can be amplified from both males (XY) and females (XX). Exons 1b/2b and 7b are also always paired, but can be amplified only from females. We conclude that porcine amelogenin is expressed from separate genes on the X and Y chromosomes, and not, as previously proposed, from a single gene with two promoters.
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Ren, Tianheng, Zhi Li, Benju Yan, Feiquan Tan, Zongxiang Tang, Shulan Fu, Manyu Yang, and Zhenglong Ren. "Targeted Segment Transfer from Rye Chromosome 2R to Wheat Chromosomes 2A, 2B, and 7B." Cytogenetic and Genome Research 151, no. 1 (2017): 50–59. http://dx.doi.org/10.1159/000458743.
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Increased chromosome instability was induced by a rye (Secale cereale L.) monosomic 2R chromosome into wheat (Triticum aestivum L.). Centromere breakage and telomere dysfunction result in high rates of chromosome aberrations, including breakages, fissions, fusions, deletions, and translocations. Plants with target traits were sequentially selected to produce a breeding population, from which 3 translocation lines with target traits have been selected. In these lines, wheat chromosomes 2A, 2B, and 7B recombined with segments of the rye chromosome arm 2RL. This was detected by FISH analysis using repeat sequences pSc119.2, pAs1 and genomic DNA of rye together as probes. The translocation chromosomes in these lines were named as 2ASMR, 2BSMR, and 7BSMR. The small segments that were transferred into wheat consisted of pSc119.2 repeats and other chromatin regions that conferred resistance to stripe rust and expressed target traits. These translocation lines were highly resistant to stripe rust, and expressed several typical traits that were associated with chromosome arm 2RL, which are better than those of its wheat parent, disomic addition, and substitution lines that show agronomic characteristics. The integration of molecular methods and conventional techniques to improve wheat breeding schemes are discussed.
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Brdar-Jokanovic, Milka, Dragana Trkulja, Emilija Nikolic-Djoric, Ankica Kondic-Spika, and Borislav Kobiljski. "The possibilities of applying marker assisted selection in breeding boron tolerant wheat." Genetika 45, no. 3 (2013): 769–76. http://dx.doi.org/10.2298/gensr1303769j.
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The aim of this study was to investigate the possibilities of applying molecular markers-microsatellites in breeding boron tolerant wheat. The study comprised the investigation of allelic variability of sixty bread wheat accessions in two microsatellite loci (Xgwm46-7B and Xgwm577-7B) for which was assumed that are placed near the 7B chromosome locus involved in the expression of boron tolerance in wheat. Phenotypic variability concerning boron tolerance was assessed via root length reduction of wheat seedlings grown in the presence of high external boron, applied as boric acid solution (concentrations 50, 100 and 150 mg/l, boron treatments B50, B100 and B150). The indication of marker-trait associations was determined by comparing the allelic variability in the two microsatellite loci with the phenotypic variability in boron tolerance. Nonparametric Kruskal-Wallis test was used for the comparisons. The indication of marker-trait association was found for both Xgwm46-7B and Xgwm577-7B; on B150 and B50 treatments, respectively. Allelic forms identified in Xgwm577-7B locus may be related to tolerance, medium tolerance and sensitivity to high boron. This was not the case for Xgwm46-7B, where the identified alleles were related only to boron tolerance and sensitivity. Therefore, Xgwm577-7B may be preferred over Xgwm46-7B when studying boron tolerance in wheat. However, a considerable portion of boron tolerant accessions carried different alleles in the investigated loci, implying boron tolerance as a quantitative trait with more than one chromosomal region involved in its expression. Therefore, the allelic variability of more than the analyzed two loci should be investigated.
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Zhou, Caie, Zhaonian Dong, Ting Zhang, Jianhui Wu, Shizhou Yu, Qingdong Zeng, Dejun Han, and Wei Tong. "Genome-Scale Analysis of Homologous Genes among Subgenomes of Bread Wheat (Triticum aestivum L.)." International Journal of Molecular Sciences 21, no. 8 (April 24, 2020): 3015. http://dx.doi.org/10.3390/ijms21083015.
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Determining the distribution and correspondence of genome-scale homologous genes in wheat are effective ways to uncover chromosome rearrangement that has occurred during crop evolution and domestication, which can contribute to improvements in crop breeding. High-resolution and comprehensive analysis of the wheat genome by the International Wheat Genome Sequencing Consortium (IWGSC) revealed a total of 88,733 high-confidence homologous genes of four major types (1:1:1, 1:1:0, 0:1:1 and 1:0:1) among the A, B and D subgenomes of wheat. This data was used to compare homologous gene densities among chromosomes, clarify their distribution and correspondence relationship, and compare their functional enrichment. The average density of 1:1:1 homologous genes was about 10 times more than the density of the other three types of homologous genes, although the homologous gene densities of the various chromosomes were similar within each homologous type. Three regions of exceptional density were detected in 1:1:1 homologous genes, the isolate peak on the tail of chromosome 4A, and the desert regions at the start of chromosome 7A and 7D. The correspondence between homologous genes of the wheat subgenomes demonstrated translocation between the tail segments of chromosome 4A and 5A, and the inversion of the segment of original 5A and 7B into the tail of 4A. The homologous genes on the inserting segments of 5A and 7B to 4A were highly enriched in nitrogen, primary metabolite and small molecular metabolism processes, compared with genes on other regions of the original 4A chromosome. This study provides a refined genome-scale reference of homologous genes for wheat molecular research and breeding, which will help to broaden the application of the wheat genome and can be used as a template for research on other polyploid plants.
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Lelley, T., E. Kazman, K. M. Devos, and M. D. Gale. "Use of RFLPs to determine the chromosome composition of tetraploid triticale (A/B)(A/B)RR." Genome 38, no. 2 (April 1, 1995): 250–54. http://dx.doi.org/10.1139/g95-031.
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Tetraploid triticale, (A/B)(A/B)RR (2n = 28), is a botanical novelty, an amphiploid composed of a diploid rye and a 14 chromosome wheat genome made up of chromosomes of the A and B genomes of tetraploid wheat. Restriction fragment length polymorphism (RFLP) markers were used to elucidate the chromosome composition of the mixed wheat genome of 35 different tetraploid triticale lines. Of 128 possible A/B chromosome pair combinations, only 6 were found among these lines, with a prevalence of the 1A, 2A, 3B, 4B, 5B, 6B, and 7B karyotype. In most triticale lines stable wheat genomes made up of only homologous A or B genome chromosome pairs were identified, however, in some lines homoeologous chromosome pairs were found. In this paper we demonstrate that RFLPs can be used successfully as an alternative to C-banding for the identification of the chromosome composition of tetraploid triticale and discuss the possible selective advantage of specific chromosome composition.Key words: tetraploid triticale, mixed wheat genome, RFLR
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Francki, M. G., O. R. Crasta, H. C. Sharma, H. W. Ohm, and J. M. Anderson. "Structural organization of an alien Thinopyrum intermedium group 7 chromosome in U.S. soft red winter wheat (Triticum aestivum L.)." Genome 40, no. 5 (October 1, 1997): 716–22. http://dx.doi.org/10.1139/g97-794.
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Barley yellow dwarf virus (BYDV) resistance in soft red winter wheat (SRWW) cultivars has been achieved by substituting a group 7 chromosome from Thinopyrum intermedium for chromosome 7D. To localize BYDV resistance, a detailed molecular genetic analysis was done on the alien group 7 Th. intermedium chromosome to determine its structural organization. Triticeae group 7 RFLP markers and rye specific repetitive sequences used in the analysis showed that the alien chromosome in the P29 substitution line has distinguishing features. The 350–480 bp rye telomeric sequence family was present on the long arm as determined by Southern and fluorescence in situ hybridization. However, further analysis using a rye dispersed repetitive sequence indicated that this alien chromosome does not contain introgressed segments from the rye genome. The alien chromosome is homoeologous to wheat chromosomes 7A and 7D as determined by RFLP analysis. Presence of the waxy gene on chromosomes 7A, 7B, and 7D but its absence on the alien chromosome in P29 suggests some internal structural differences on the short arm between Th. intermedium and wheat group 7 chromosomes. The identification of rye telomeric sequences on the alien Thinopyrum chromosome and the homoeology to wheat chromosomes 7A and 7D provide the necessary information and tools to analyze smaller segments of the Thinopyrum chromosome and to localize BYDV resistance in SRWW cultivars.Key words: barley yellow dwarf virus, Thinopyrum intermedium, rye repetitive sequences, RFLP, homoeologous group 7.
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Khalid, Maria, Alvina Gul, Rabia Amir, Mohsin Ali, Fakiha Afzal, Umar Masood Quraishi, Zubair Ahmed, and Awais Rasheed. "QTL mapping for seedling morphology under drought stress in wheat cross synthetic (W7984)/Opata." Plant Genetic Resources: Characterization and Utilization 16, no. 4 (March 13, 2018): 359–66. http://dx.doi.org/10.1017/s1479262118000023.
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AbstractDrought stress ‘particularly at seedling stage’ causes morpho-physiological differences in wheat which are crucial for its survival and adaptability. In the present study, 209 recombinant inbred lines (RILs) from synthetic wheat (W7984)× ‘Opata’ (also known as SynOpRIL) population were investigated under well-watered and water-limited conditions to identify quantitative trait loci (QTL) for morphological traits at seedling stage. Analysis of variance revealed significant differences (P < 0.01) among RILs, and water treatments for all traits with moderate to high broad sense heritability. Pearson's coefficient of correlation revealed positive correlation among all traits except dry root weight that showed poor correlation with fresh shoot weight (FSW) under water-limited conditions. A high-density linkage map was constructed with 2639 genotyping-by-sequencing markers and covering 5047 cM with an average marker density of 2 markers/cM. Composite interval mapping identified 16 QTL distributed over nine chromosomes, of which six were identified under well-watered and 10 in water-limited conditions. These QTL explained from 4 to 59% of the phenotypic variance. Six QTL were identified on chromosome 7B; three for shoot length under water-limited conditions (QSL.nust-7B) at 64, 104 and 221 cM, two for fresh root weight (QFRW.nust-7B) at 124 and 128 cM, and one for root length (QRL.nust-7B) at 122 cM positions. QFSW.nust-7B appeared to be the most significant QTL explaining 59% of the phenotypic variance and also associated with FSW at well-watered conditions. These QTL could serve as target regions for candidate gene discovery and marker-assisted selection in wheat breeding.
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Jamil, Muhammad, Aamir Ali, Alvina Gul, Abdul Ghafoor, Amir M. H. Ibrahim, and Abdul Mujeeb-Kazi. "Genome-Wide Association Studies for Spot Blotch (Cochliobolus sativus) Resistance in Bread Wheat Using Genotyping-by-Sequencing." Phytopathology® 108, no. 11 (November 2018): 1307–14. http://dx.doi.org/10.1094/phyto-02-18-0047-r.
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Spot blotch is a severe biotic menace of wheat caused by Cochliobolus sativus (syn. Bipolaris sorokiniana). Spot blotch is liable to major yield losses in warm humid regions. A genome-wide association study using genotyping-by-sequencing (GBS) markers was conducted to identify genomic regions associated with spot blotch resistance in a diversity panel of 159 spring wheat genotypes. In total, 87,096 GBS markers covering the whole genome, with an average polymorphism information content value of 0.276, were applied. Linkage disequilibrium (LD) analysis indicated that the LD decay extent was approximately 100 Mbp. The panel was evaluated for disease severity (DS) and area under disease progress curve (AUDPC) for 2 years. In total, 24 marker-trait associations (MTA) were identified for DS and AUDPC of spot blotch, with 11 on chromosome 5B, 3 on 3A, 2 on 6B, and 1 each on 1A, 2A, 1D, 2D, 4B, 5A, 7A, and 7B. A marker on chromosome 7B significantly explained 14% of the phenotypic variation of spot blotch severity as well as 11% of AUDPC. Five markers—three on chromosome 5B, one on 3A, and one on 7B—were associated with both DS and AUDPC with R2 ranging from 8 to 12%. Significant MTA can be utilized to develop wheat germplasm with resistance to spot blotch.
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Moens, Peter B., Cecilia Bernelot-Moens, and Barbara Spyropoulos. "Chromosome core attachment to the meiotic nuclear envelope regulates synapsis in Chloealtis (Orthoptera)." Genome 32, no. 4 (August 1, 1989): 601–10. http://dx.doi.org/10.1139/g89-488.
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Genetic evidence shows that in inbred families of Chloealtis conspersa, exceptional synapsis occurs between the distal ends of chromosomes 7 and 8 only if the other chromosome 7 carries a supernumerary (B) segment at its distal end. Cytological evidence shows that all the ends of chromosome cores are attached to the nuclear envelope and that synapsis is initiated close to the nuclear envelope. It is shown that distal synapsis of homologues 7 and 7B is perturbed by the B segment, which causes a misalignment of normally homologous regions at the nuclear envelope. It is proposed that this misalignment permits ends of heterologous chromosomes to undergo synapsis if they have mutual distal homologies (common in grasshoppers). In this manner the association between chromosome core ends and nuclear envelope regulates synapsis and chiasma formation in Chloealtis. Other organisms have different heterochromatic polymorphisms and pairing modes, but chiasma redistribution may result from a similar mechanism.Key words: Orthoptera, synaptonemal complex, synapsis regulation, heterologous synapsis, meiosis, nuclear envelope, heterochromatin.
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Lukaszewski, Adam J., Barbara Apolinarska, J. Perry Gustafson, and K. D. Krolow. "Chromosome pairing and aneuploidy in tetraploid triticale. I. Stabilized karyotypes." Genome 29, no. 4 (August 1, 1987): 554–61. http://dx.doi.org/10.1139/g87-093.
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Among 38 lines of tetraploid triticale analyzed at meiosis, the number of paired arms per rye chromosome ranged from 1.14 to 1.76 and from 1.46 to 1.96 per wheat chromosome. The frequency of cells without univalents ranged from 22 to 90%. Pairing frequencies within rye and wheat genomes were correlated in all groups of lines. Lines without wheat chromosome 3B showed reduced pairing in both genomes, while lines with an additional pair of 5R chromosomes substituted for group-5 wheat chromosomes showed improved pairing of the rye genome but not of the wheat genome. In the rye genome, the chromosome arms that carry major blocks of telomeric heterochromatin paired with an average of 25.1% lower frequency than the arms without the telomeric heterochromatin, the difference being attributed to the difference in arm length and not to the presence of heterochromatic blocks. In the wheat genome, chromosome arms IBS, 5AS, and 5BS and chromosomes 4A and 7B paired with significantly lower frequency than the remaining arms of wheat chromosomes. Average aneuploid frequency in a sample of 1383 plants was 4.55%, with the mean value of 5.77% in lines with 14 wheat and 14 rye chromosomes, and 2.01% in lines with an extra pair of 5R chromosomes. The results indicate that while the meiotic pairing is poorer and aneuploid frequency is higher than previously believed, tetraploid triticales are nevertheless chromosomally much more stable than hexaploid or octoploid triticales. Key words: C-banding, heterochromatin, paired arms, chromosome substitution.
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Herrera-Foessel, S. A., R. P. Singh, J. Huerta-Espino, H. M. William, V. Garcia, A. Djurle, and J. Yuen. "Identification and Molecular Characterization of Leaf Rust Resistance Gene Lr14a in Durum Wheat." Plant Disease 92, no. 3 (March 2008): 469–73. http://dx.doi.org/10.1094/pdis-92-3-0469.
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Leaf rust, caused by Puccinia triticina, is an important disease of durum wheat (Triticum turgidum subsp. durum) and only a few designated resistance genes are known to occur in this crop. A dominant leaf rust resistance gene in the Chilean durum cv. Llareta INIA was mapped to chromosome arm 7BL through bulked segregant analysis using the amplified fragment length polymorphism (AFLP) technique, and by mapping three polymorphic markers in the common wheat (T. aestivum) International Triticeae Mapping Initiative population. Several simple sequence repeat (SSR) markers, including Xgwm344-7B and Xgwm146-7B, were associated with the leaf rust resistance gene. Resistance response and chromosomal position indicated that this gene is likely to be Lr14a. The SSR markers Xgwm344-7B and Xgwm146-7B and one AFLP marker also differentiated common wheat cv. Thatcher from the near-isogenic line with Lr14a, as well as durum ‘Altar C84’ from durum wheat with Lr14a. This is the first report of the presence of Lr14a in durum wheat, although the gene originally was transferred from emmer wheat ‘Yaroslav’ to common wheat. Lr14a is also present in CIMMYT-derived durum ‘Somateria’ and effective against Mexican and other P. triticina races of durum origin. Lr14a should be deployed in combination with other effective leaf rust resistance genes to prolong its effectiveness in durum wheat.
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Yang, Xiaoying, Maoru Xu, Yongfu Wang, Xiaofang Cheng, Chenxi Huang, Hong Zhang, Tingdong Li, et al. "Development and Molecular Cytogenetic Identification of Two Wheat-Aegilops geniculata Roth 7Mg Chromosome Substitution Lines with Resistance to Fusarium Head Blight, Powdery Mildew and Stripe Rust." International Journal of Molecular Sciences 23, no. 13 (June 24, 2022): 7056. http://dx.doi.org/10.3390/ijms23137056.
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Fusarium head blight (Fhb), powdery mildew, and stripe rust are major wheat diseases globally. Aegilops geniculata Roth (UgUgMgMg, 2n = 4x = 28), a wild relative of common wheat, is valuable germplasm of disease resistance for wheat improvement and breeding. Here, we report the development and characterization of two substitution accessions with high resistance to powdery mildew, stripe rust and Fhb (W623 and W637) derived from hybrid progenies between Ae. geniculata and hexaploid wheat Chinese Spring (CS). Fluorescence in situ hybridization (FISH), Genomic in situ hybridizations (GISH), and sequential FISH-GISH studies indicated that the two substitution lines possess 40 wheat chromosomes and 2 Ae. geniculata chromosomes. Furthermore, compared that the wheat addition line parent W166, the 2 alien chromosomes from W623 and W637 belong to the 7Mg chromosomes of Ae. geniculata via sequential FISH-GISH and molecular marker analysis. Nullisomic-tetrasomic analysis for homoeologous group-7 of wheat and FISH revealed that the common wheat chromosomes 7A and 7B were replaced in W623 and W637, respectively. Consequently, lines W623, in which wheat chromosomes 7A were replaced by a pair of Ae. geniculata 7Mg chromosomes, and W637, which chromosomes 7B were substituted by chromosomes 7Mg, with resistance to Fhb, powdery mildew, and stripe rust. This study has determined that the chromosome 7Mg from Ae. geniculata exists genes resistant to Fhb and powdery mildew.
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Liu, Cheng, Guang-Rong Li, Wen-Ping Gong, Gen-Ying Li, Ran Han, Hao-Sheng Li, Jian-Min Song, et al. "Molecular and Cytogenetic Characterization of a Powdery Mildew-Resistant Wheat-Aegilops mutica Partial Amphiploid and Addition Line." Cytogenetic and Genome Research 147, no. 2-3 (2015): 186–94. http://dx.doi.org/10.1159/000443625.
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Aegilops mutica Boiss., a diploid species (2n = 2x = 14, TT), has been rarely studied before. In this research, a hexaploid wheat (cv. Chinese Spring)-Ae. mutica partial amphiploid and a wheat-Ae. mutica addition line were characterized by chromosome karyotyping, FISH using oligonucleotides Oligo-pTa535-1, Oligo-pSc119.2-1, and (GAA)8 as probes, and EST-based molecular markers. The results showed that the partial amphiploid strain consisted of 20 pairs of wheat chromosomes and 7 pairs of Ae. mutica chromosomes, with both wheat 7B chromosomes missing. EST-based molecular marker data suggested that the wheat-Ae. mutica addition line carries the 7T chromosome. Resistance tests indicated that both the partial amphiploid and the 7T addition line were highly resistant to powdery mildew, whereas the wheat control line Chinese Spring was highly susceptible, indicating the presence of a potentially new powdery mildew resistance gene on the Ae. mutica 7T chromosome. The karyotype, FISH patterns, and molecular markers can now be used to identify Ae. mutica chromatin in a wheat background, and the 7T addition could be used as a new powdery mildew resistance source for wheat breeding.
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Hetrick, B. A. D., G. W. T. Wilson, B. S. Gill, and T. S. Cox. "Chromosome location of mycorrhizal responsive genes in wheat." Canadian Journal of Botany 73, no. 6 (June 1, 1995): 891–97. http://dx.doi.org/10.1139/b95-097.
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Symbiotic relationships between wheat plants and mycorrhizal fungi may play an important role in the growth and productivity of wheat as a crop. Wheat cultivars differ in their ability to form such relationships, but little is known concerning the genetic basis of such differences. A set of intervarietal substitution lines having individual chromosomes from 'Cheyenne' (nonresponsive to mycorrhizae) substituted into 'Chinese Spring' (nonresponsive to mycorrhizae) were tested for mycorrhizal response in greenhouse experiments. Chromosomes 1A, 5B, 6B, 7B, 5D, and 7D of 'Cheyenne' had positive effects on the trait, with homologous groups 5 and 7 in the B and D genomes having the largest effects. Chromosome 5B of 'Hope', a nonresponsive cultivar, also had a positive effect in a 'Chinese Spring' background. In addition, the mycorrhizal responsiveness of a range of other cultivars and ancestors was tested to expand information on the trait in wheat and its relatives. Data on chromosome location of mycorrhizal-response genes and genotypic responsiveness will permit more effective genetic manipulation of this trait. Key words: pathogenesis, growth response, vesicular–arbuscular mycorrhizae.
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González, M. J., and A. Cabrera. "Identification of wheat and tritordeum chromosomes by genomic in situ hybridization using total Hordeum chilense DNA as probe." Genome 42, no. 6 (December 1, 1999): 1194–200. http://dx.doi.org/10.1139/g99-028.
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Total genomic Hordeum chilense DNA probe was hybridized to somatic chromosome spreads of Triticum aestivum 'Chinese Spring' and to four advanced tritordeum lines, the latter being the fertile amphiploid between H. chilense and durum wheat (2n = 6x = 42, AABBHchHch). The probe hybridized strongly to the B-genome chromosomes and to one or two bands on the A-genome chromosomes present in both wheat and tritordeum alloploids. Bands on chromosomes 1D, 2D, and 7D from hexaploid wheat were also detected. Genomic H. chilense DNA probe identified 16 chromosome pairs of the chromosome complement of hexaploid wheat and all A- and B-genome chromosomes present in the tritordeum amphiploids. The in situ hybridization patterns observed correspond to those previously reported in wheat by both N-banding and in situ hybridization with the GAA-satellite sequence (Pedersen and Langridge 1997), allowing the identification of these chromosomes. Variation among the tritordeum amphiploids for hybridization sites on chromosomes 2A, 4A, 6A, 7A, 4B, 5B, and 7B was observed. Despite of this polymorphism, all lines shared the general banding pattern. When used as probe, total H. chilense genomic DNA labeled the H. chilense chromosomes over their lengths allowing the identification of 14 H. chilense chromosomes present in the tritordeum amphiploids. In addition, chromosome-specific telomeric, interstial, and centromeric hybridization sites were observed. These hybridization sites coincide with N-banded regions in H. chilense allowing the identification of the individual H. chilense chromosomes in one of the amphiploid. The N-banded karyotypes of H. chilense (accessions H1 and H7) are presented.Key words: Hordeum chilense, Triticum aestivum, chromosome identification, in situ hybridization, N-banding.
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Czyczyło-Mysza, Ilona, Izabela Marcińska, Edyta Skrzypek, Katarzyna Cyganek, Katarzyna Juzoń, and Małgorzata Karbarz. "QTL mapping for germination of seeds obtained from previous wheat generation under drought." Open Life Sciences 9, no. 4 (April 1, 2014): 374–82. http://dx.doi.org/10.2478/s11535-013-0273-y.
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AbstractThe QTLs controlling germination and early seedling growth were mapped using seeds acquired from mapping population and parental lines of Chinese Spring and SQ1 grown under water-limited conditions, severe drought (SDr) and well-watered plants (C). Germination ability was determined by performing a standard germination test based on the quantification of the germination percentage (GP24) of seeds incubated for 24 h at 25°C in the dark. Early seedling growth was evaluated on the basis of the length of the root and leaf at the 6th day of the experiment. QTLs were identified by composite interval mapping method using Windows QTLCartographer 2.5 software. For the traits studied, a total of thirty eight additive QTLs were identified. Seventeen QTLs were mapped in C on chromosomes: 1A, 2A, 7A, 1B, 2B, 3B, 4B, 5B, 6B, 7B, 2D, 3D, 4D and 6D, while twenty one QTLs were identified in SDr on chromosomes: 1A, 2A, 5A, 2B, 3B, 4B, 5B, 6B, 7B, 3D, 5D and 6D. Most of the QTLs for GP and early leaf growth parameters were clustered on chromosome 4B (associated with the Rht-B1 marker) both in C and SDr plants. The results indicate the complex and polygenic nature of germination.
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Koo, Dal-Hoe, Bernd Friebe, and Bikram S. Gill. "Homoeologous Recombination: A Novel and Efficient System for Broadening the Genetic Variability in Wheat." Agronomy 10, no. 8 (July 22, 2020): 1059. http://dx.doi.org/10.3390/agronomy10081059.
Full textAbstract:
Gene transfer from wild wheat relatives to bread wheat is restricted to homologous recombination. The presence of the Pairing homoeologous 1 (Ph1) gene in the long arm of wheat chromosome 5B allows only homologous chromosomes to pair and recombine, resulting in diploid inheritance of polyploid wheat. Previously, we identified a potent homoeologous pairing promotor gene(s) (Hpp-5Mg); its carrier chromosome 5Mg derived from Aegilops geniculata and its wheat homoeologous chromosome 5D freely recombined in the presence of the Ph1 gene. In this study, we investigated the effect of Hpp-5Mg on homoeologous recombination in the absence of Ph1. In Hpp-5Mg/ph1bph1b plants, we observed a vast genome-wide increase in homoeologous recombination and multiple crossovers (CO), including CO breakpoints in proximal regions of the chromosomes where recombination is known to be suppressed. We tested the efficacy of Hpp-5Mg/ph1bph1b-induced homoeologous recombination by producing new recombinants for the wheat streak mosaic virus resistance gene, Wsm3, present in the wheat-Thinopyrum intermedium Robertsonian translocation (RobT T7BS.7S#3L). A recombination frequency of 6.5% was detected by screening the progenies double monosomic for T7BS.7S#3L and 7B by genomic in situ hybridization. This recombination frequency was about 100-fold higher compared with the recombinant frequency of 0.06% observed by using ph1b-induced homoeologous recombination alone. Our results indicate that chromosome 5Mg promotes homoeologous recombination between wheat and wild wheat relative chromosomes, which helps in the generation of pre-breeding materials thereby accelerating wheat crop improvement.
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Sourdille, P., J. W. Snape, T. Cadalen, G. Charmet, N. Nakata, S. Bernard, and M. Bernard. "Detection of QTLs for heading time and photoperiod response in wheat using a doubled-haploid population." Genome 43, no. 3 (June 1, 2000): 487–94. http://dx.doi.org/10.1139/g00-013.
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The genetic basis of heading time in wheat (Triticum aestivum L.) was investigated through the study of flowering under normal autumn sown field conditions as well as photoperiod responses under a controlled environment. Quantitative trait loci (QTLs) for these traits were mapped in a doubled-haploid (DH) population derived from a cross between the wheat cultivars 'Courtot' and 'Chinese Spring'. A molecular marker linkage map of this cross that was previously constructed based on 187 DH lines and 380 markers was used for QTL mapping. The genome was well covered (85%) except for chromosomes 1D and 4D, and a set of anchor loci regularly spaced over the genome (one marker each 15.5 cM) was chosen for marker regression analysis. The presence of a QTL was declared at a significance threshold of alpha = 0.005. The population was grown under field conditions in Clermont-Ferrand, France during two years (1994-1995), in Norwich, U.K. over one year (1998), and also under controlled environments in Norwich. For each trait, between 2 and 4 QTLs were identified with individual effects ranging between 6.3% and 44.4% of the total phenotypic variation. Two QTLs were detected that simultaneously affected heading time and photoperiod response. For heading time, these two QTLs were detected in more than one year. One QTL located on chromosome arm 2BS near the locus Xfbb121-2B, co-segregated with the gene Ppd-B1 known to be involved in photoperiod response. This chromosome region explained a large part of the variation (23.4-44.4% depending on the years or the traits). Another region located on chromosome arm 7BS between the loci Xfbb324-7B and Xfbb53-7B also had a strong effect (7.3-15.3%). This region may correspond to a QTL for earliness per se.Key words: molecular markers, Triticum aestivum, Ppd, Vrn.
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Zhang, Xiaocun, Yanwu Fu, Yiru Xu, and Ying Guo. "Quantitative trait loci for sensory and textural properties of Chinese white noodles from a population of recombinant inbred lines of winter wheat." Crop and Pasture Science 69, no. 4 (2018): 347. http://dx.doi.org/10.1071/cp17371.
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In this paper, we detected quantitative trait loci (QTLs) for two of the most important quality factors of Chinese white noodles (CWN), sensory quality and textural properties, using a recombinant inbred line (RIL) population containing 184 lines derived from the cross between two Chinese winter wheat (Triticum aestivum L.) varieties, Linmai6 and Tainong18. Twenty-six QTLs for eight sensory quality traits were identified on chromosomes 1A, 2A, 3A, 4A, 5A, 6A, 2B, 3B 4B, 5B, 6B 7B, 2D, 4D, 5D and 6D that explained 7.0–16.84% of the phenotypic variance. Fourteen QTLs associated with textural quality traits were identified on chromosomes 1B, 2D, 3A, 3B, 4A, 5B, 5D and 7D that explained 5.94–13.15% of the phenotypic variance. Six QTLs associated with hardness, adhesiveness, cohesiveness, gumminess, resilience and appearance were mapped to chromosome 4A, indicating that this chromosome was important for textural and sensory properties of CWN. This study furthers understanding of the genetic basis for sensory quality and textural properties of CWN and provides the basis for gene mapping of these traits.
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Atienza, S. G., C. M. Avila, and A. Martín. "The development of a PCR-based marker for PSY1 from Hordeum chilense, a candidate gene for carotenoid content accumulation in tritordeum seeds." Australian Journal of Agricultural Research 58, no. 8 (2007): 767. http://dx.doi.org/10.1071/ar06338.
Full textAbstract:
Hexaploid tritordeums are the amphiploids derived from the cross between the wild barley Hordeum chilense and durum wheat. Tritordeums are characterised by higher yellow pigment content in their seeds than their durum wheat progenitors due to certain H. chilense genes located on the α arm of chromosome 7Hch. In this work a candidate gene approach based on the phytoene synthase gene (PSY) was followed to investigate whether PSY1 may be responsible for the high carotenoid content in tritordeum and to develop a diagnostic marker for H. chilense PSY. This gene codes for the first step in the carotenoid biosynthetic pathway. It was first demonstrated that PSY is duplicated in H. chilense, Triticum urartu, and durum wheat (PSY1 and PSY2), and subsequently a diagnostic cleaved amplified polymorphism (CAP) marker able to differentiate between H. chilense and durum wheat PSY1 was developed. Using this CAP marker and a set of H. chilense-common wheat addition lines it was found that PSY1 is located on the α arm of chromosome 7Hch, where the gene(s) for yellow pigment content are located. PSY1 is located on chromosomes 7A and 7B of durum wheat as demonstrated using Langdon substitution lines. Furthermore, synteny between rice and wheat indicates that PSY1 should be located on the long arms of chromosomes 7A and 7B, in agreement with QTL data for yellow pigment content. Together, these results suggest that PSY1 may be a good candidate gene for further work with yellow pigment content in both durum wheat and tritordeum. In addition, the diagnostic CAP marker developed will be used in our breeding program to transfer H. chilense genes to durum wheat, to evaluate their potential for durum wheat improvement.
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Mohammady-D, Shahram, Keith Moore, John Ollerenshaw, and Behrooz Shiran. "Backcross reciprocal monosomic analysis of leaf relative water content, stomatal resistance, and carbon isotope discrimination in wheat under pre-anthesis water-stress conditions." Australian Journal of Agricultural Research 56, no. 10 (2005): 1069. http://dx.doi.org/10.1071/ar05038.
Full textAbstract:
Monosomic plants from an Australian variety (Oxley) having low stomatal resistance (SR), low leaf relative water content (LRWC), and high carbon isotope discrimination (Δ) were crossed with variety Falchetto having opposite characters in order to produce F2 backcross reciprocal monosomic families. The families were assessed under pre-anthesis water-stress conditions in a controlled growth chamber. F2 backcross reciprocal monosomic analysis suggested possible allelic variations between chromosomes 1A, 3A, 6A, 7A, 7B, 1D, and 4D of Falchetto and their homologues in Oxley for LRWC. This analysis also suggested possible allelic variation between chromosomes 5A, 1A, and 3A of Falchetto and their homologues in Oxley for SR. Extending the analysis to the F3 disomic generation and the assessment of LRWC at this generation confirmed that reciprocals for chromosomes 3A and 6A showed significant differences. F2 backcross reciprocal monosomic analysis for Δ suggested allelic variations on chromosomes 1D, 4D, and 5D. However, chromosome 1D from Falchetto had the highest difference from its homologue in Oxley. Assessing the reciprocals of this chromosome for vegetative evapotranspiration efficiency (ETEveg) at the F3 disomic generation indicated that the observed variation for Δ was translated into differences for ETEveg. These results indicate that chromosome 1D of Falchetto is promising in reducing Δ and that the improvement of wheat varieties for ETEveg can be done by selection for Δ. Finally, plieotropic effects of some chromosomes were observed for the characters under study. This suggests the existence of genetic factors on these chromosomes affecting more than one character. However, some pleiotropic effects could also be due to non-genetic developmental interactions.
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Davoyan, R. O., I. V. Bebyakina, E. R. Davoyan, D. S. Mikov, Yu S. Zubanova, D. M. Boldakov, E. D. Badaeva, I. G. Adonina, E. A. Salina, and A. N. Zinchenko. "The development and study of common wheat introgression lines derived from the synthetic form RS7." Vavilov Journal of Genetics and Breeding 23, no. 7 (November 24, 2019): 827–35. http://dx.doi.org/10.18699/vj19.556.
Full textAbstract:
Synthetic recombination form RS7 (BBAAUS), in which the first two genomes, A and B, originate from common wheat, and the third recombinant genome consists of Aegilops speltoides (S) and Ae. umbellulata (U) chromosomes, was obtained from crossing synthetic forms Avrodes (BBAASS) and Avrolata (BBAAUU). Resistant to leaf rust, yellow rust and powdery mildew, introgression lines have been obtained from backcrosses with the susceptible varieties of common wheat Krasnodarskaya 99, Fisht and Rostislav. PCR analysis showed the presence of amplification fragments with marker SCS421 specific for the Lr28 gene in the line 4991n17. The cytological study (С-banding and FISH) of 14 lines has revealed chromosomal modifications in 12 of them. In most cases, the lines carry translocations from Ae. speltoides, which were identified in chromosomes 1D, 2D, 3D, 2B, 4B, 5B and 7B. Also, lines with the substituted chromosomes 1S (1B), 4D (4S), 5D (5S) and 7D (7S) were identified. Lines that have genetic material from Ae. speltoides and Ae umbellulata at once were revealed. In the line 3379n14, translocations in the short arm of chromosome 7D from Ae. umbellulata and chromosomes 5BL, 1DL, 2DL from Ae. speltoides were revealed. The line 4626p16 presumably has a translocation on the long arm of chromosome 2D from Ae. umbellulata and the T7SS.7SL-7DL translocation from Ae. speltoides. The T1DS.1DL-1SL and T3DS.3DL-3SL translocations from Ae. speltoides, and T2DS.2DL-2UL and T7DL.7DS-7US from Ae. umbellulata have been obtained for the first time. These lines may carry previously unidentified disease resistance genes and, in particular, leaf rust resistance genes from Ae. speltoides and Ae. umbellulata.
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Iehisa, Julio C. M., Yumeto Kurahashi, and Shigeo Takumi. "Identification of chromosomes controlling abscisic acid responsiveness and transcript accumulation of Cor - Lea genes in common wheat seedlings." Functional Plant Biology 38, no. 10 (2011): 758. http://dx.doi.org/10.1071/fp11092.
Full textAbstract:
Abiotic stresses, such as cold, drought or high salinity, seriously affect plant growth and reduce yield in crop species including common wheat (Triticum aestivum L.). The phytohormone ABA plays important roles in plant adaptation to abiotic stress. We compared responsiveness to exogenous ABA, based on root growth inhibition by ABA, among three common wheat cultivars. Seedlings of the cultivars Cheyenne (Cnn) and Hope showed higher ABA responsiveness and higher levels of Cor (cold-responsive)–Lea (late embryogenesis abundant) gene expression than seedlings of Chinese Spring (CS). The chromosomes involved in the regulation of ABA responsiveness and Cor–Lea expression were identified using chromosome substitution lines, in which a chromosome pair of CS was substituted for the corresponding homologous pair of Cnn or Hope. In the CS–Cnn substitution lines, chromosomes 3A, 5A, 5D and 7A increased the ABA responsiveness of CS. Chromosomes 3A and 5A were also involved in the regulation of Cor–Lea gene expression and stomatal response during leaf dehydration. Substitution of CS chromosomes 3A or 5A with the respective homologous pair from Hope also enhanced ABA responsiveness and Cor–Lea expression. In addition, the factors present on chromosomes 4D and 7B of highly responsive cultivars increased Wrab17 expression but had little or no effect on ABA responsiveness. Cultivar differences in ABA responsiveness appear to be determined by genes present on these specific chromosomes in common wheat.
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Liu, C. J., S. Chao, and M. D. Gale. "Wsp-1, a set of genes controlling water-soluble proteins in wheat and related species." Genetical Research 54, no. 3 (December 1989): 173–81. http://dx.doi.org/10.1017/s0016672300028639.
Full textAbstract:
SummaryThree water-soluble wheat endosperm proteins of the wheat variety Chinese Spring have been shown, by isoelectric focusing, to be the products of genes located on the long arms of chromosomes 7A, 7B and 7D. In the absence of any evidence of function these genes have been assigned the temporary symbol, Wsp-1.Considerable intervarietal variation was found among a sample of 44 hexaploid wheat varieties. Five alleles at Wsp-A1, three at Wsp-B1 and two at Wsp-D1 were identified. Intrachromosomal mapping showed that Wsp-B1 is located distally on the long arm of chromosome 7B.Alien homoeoloci were identified on chromosomes 7Hch of Hordeum chilense, 7H of H. vulgare, 7E of Agropyron elongatum, 7S1 of Aegilops sharonensis and 7V of Dasypyrum villosum. Some other loci encoding WSPs found in wheat and some alien species are also briefly described.
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Xu, Jie, R. L. Conner, and A. Laroche. "C-banding and fluorescence in situ hybridization studies of the wheat–alien hybrid 'Agrotana'." Genome 37, no. 3 (June 1, 1994): 477–81. http://dx.doi.org/10.1139/g94-066.
Full textAbstract:
'Agrotana', a wheat-alien hybrid (2n = 56), is a potential source of resistance to common root rot, stem rust, wheat streak mosaic virus, and the wheat curl mite. However, the origin of 'Agrotana', reported to be durum wheat × Agropyron trichophorum (pubescent wheatgrass), is uncertain. The objective of this investigation was to determine the chromosome constitution of 'Agrotana' using C-banding and fluorescence in situ hybridization techniques. The F1 hybrid of 'Agrotana' × 'Chinese Spring' wheat showed 7 I + 21 II in 14.9% of the pollen mother cells, evidence of the presence of the A, B, and D genomes in 'Agrotana'. The hybrid had 16 heavily C-banded chromosomes, namely 4A, and 1-7B of wheat, and a translocation that probably involved wheat chromosomes 2A and 2D. In situ hybridization using biotinylated genomic DNA of Ag. trichophorum cv. Greenleaf blocked with CS DNA failed to identify the alien chromosomes in 'Agrotana', indicating that the alien chromosomes were not likely derived from pubescent wheatgrass. In situ hybridization using labelled wheat genomic DNA blocked with 'Agrotana' DNA revealed that 'Agrotana' had 40 wheat, 14 alien, and 2 (a pair) wheat–alien translocated chromosomes. There was no homology between wheat and the alien chromosomes or chromosome segments involved in the wheat–alien recombinant. Two of the seven pairs of alien chromosomes were homoeologous to each other. The ability to identify alien chromatin in wheat using labelled wheat DNA instead of labelled alien DNA will be particularly useful in chromosome engineering of wheat germplasms having alien chromatin of unknown origin.Key words: wheat–alien hybrid, C-banding, fluorescence in situ hybridization, labelled wheat DNA as probe.
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Yang, Huali, Qinqin Yang, Yiwei Kang, Miao Zhang, Xiaodeng Zhan, Liyong Cao, Shihua Cheng, Weixun Wu, and Yingxin Zhang. "Finding Stable QTL for Plant Height in Super Hybrid Rice." Agriculture 12, no. 2 (January 24, 2022): 165. http://dx.doi.org/10.3390/agriculture12020165.
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Plant height (PH) is one of the most important agronomic traits determining plant architecture in rice. To investigate the genetic basis of plant height in the high-yielding hybrid rice variety Nei2You No.6, recombinant inbred sister lines (RISLs) were used to map quantitative trait loci (QTL) over four years. A total of 19 minor/medium-effect QTLs were mapped on eleven chromosomes except chromosome 10, totally explaining 44.61–51.15% phenotypic variance in four environments. Among these, qPH-1a, qPH-1b, qPH-2b, qPH-3b, qPH-6, and qPH-7b were repeatedly detected over four years. Among these, the qPH-6 was mapped to an interval of 22.11–29.41 Mb on chromosome 6L, which showed the highest phenotypic variation explained (PVE) of 10.22–14.05% and additive effect of 3.45–4.63. Subsequently, evaluation of near isogenic lines (NILs) showed that the qPH-6 allele from the restorer line (R8006) could positively regulate plant height, resulting in an 18.50% increase in grain yield. These results offered a basis for further mapping of qPH-6 and molecular breeding in improving plant architecture in rice.
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Wang, Xiaolu, Ran Han, Zhiwei Chen, Jianbo Li, Tong Zhu, Jun Guo, Wenjing Xu, et al. "Identification and Evaluation of Wheat–Aegilops bicornis Lines with Resistance to Powdery Mildew and Stripe Rust." Plant Disease 106, no. 3 (March 1, 2022): 864–71. http://dx.doi.org/10.1094/pdis-05-21-0982-re.
Full textAbstract:
Wheat pathogens, especially those causing powdery mildew and stripe rust, seriously threaten yield worldwide. Utilizing newly identified disease resistance genes from wheat relatives is an effective strategy to minimize disease damage. In this study, chromosome-specific molecular markers for the 3Sb and 7Sb chromosomes of Aegilops bicornis were developed using PCR-based landmark unique gene primers for screening wheat–A. bicornis progenies. Fluorescence in situ hybridization (FISH) was performed to further identify wheat–A. bicornis progenies using oligonucleotides probes Oligo-pSc119.2-1, Oligo-pTa535-1, and Oligo-(GAA)8. After establishing A. bicornis 3Sb and 7Sb chromosome-specific FISH markers, Holdfast (common wheat)–A. bicornis 3Sb addition, 7Sb addition, 3Sb(3A) substitution, 3Sb(3B) substitution, 3Sb(3D) substitution, 7Sb(7A) substitution, and 7Sb(7B) substitution lines were identified by the molecular and cytological markers. Stripe rust and powdery mildew resistance, along with agronomic traits, were investigated to evaluate the breeding potential of these lines. Holdfast and Holdfast–A. bicornis progenies were all highly resistant to stripe rust, indicating that the stripe rust resistance might derive from Holdfast. However, Holdfast–A. bicornis 3Sb addition, 3Sb(3A) substitution, 3Sb(3B) substitution, and 3Sb(3D) substitution lines showed high resistance to powdery mildew while Holdfast was highly susceptible, indicating that chromosome 3Sb of A. bicornis carries previously unknown powdery mildew resistance gene(s). Additionally, the transfer of the 3Sb chromosome from A. bicornis to wheat significantly increased tiller number, but chromosome 7Sb has a negative effect on agronomic traits. Therefore, wheat germplasm containing A. bicornis chromosome 3Sb has potential to contribute to improving powdery mildew resistance and tiller number during wheat breeding.
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Roberts, D. W. A. "Chromosomes in 'Cadet' and 'Rescue' wheats carrying loci for cold hardiness and vernalization response." Canadian Journal of Genetics and Cytology 28, no. 6 (December 1, 1986): 991–97. http://dx.doi.org/10.1139/g86-137.
Full textAbstract:
'Rescue', 'Cadet', and the 42 reciprocal chromosome substitution lines derived from these two spring wheat cultivars were tested for vernalization response and cold hardiness. Cold hardiness was tested after hardening under a 16-h day for 8 weeks with 6 °C day and 4 °C night temperatures or in the dark for 7 weeks at 0.8 °C followed by 8 weeks at −5 °C. Chromosomes 5A, 5B, 7B, and possibly 2A carried loci for vernalization response. Chromosomes 2A, 5A, and 5B carried loci affecting cold hardiness measured after 8 weeks in the light at 6 °C during the day and 4 °C at night, whereas chromosomes 6A, 3B, 5B, and 5D were involved in cold hardiness after hardening in the dark at 0.8 °C followed by −5 °C. The results suggest that the rank order of cultivars for cold hardiness depends on the hardening technique used since the two different techniques tested had different genetic and presumably somewhat different biochemical bases.Key words: Triticum aestivum L., cold hardiness, vernalization.
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Mrva, K., and D. J. Mares. "Quantitative trait locus analysis of late maturity a-amylase in wheat using the doubled haploid population Cranbrook Halberd." Australian Journal of Agricultural Research 52, no. 12 (2001): 1267. http://dx.doi.org/10.1071/ar01047.
Full textAbstract:
Mapping of the late maturity α-amylase (LMA) gene using quantitative trait locus (QTL) analysis represents an important step in identification of potential molecular markers that would greatly improve efficiency and accuracy of screening for LMA. QTL controlling the expression of LMA in wheat were detected in a doubled haploid (DH) cross/population derived from wheat (Triticum aestivum L. em. Thell) cultivars Cranbrook (LMA source) and Halberd (non-LMA). The DH population and parents were sown in replicated trials at Narrabri with sowing times differing by 2 weeks. Cool temperature treatment of detached tillers was used to induce expression of LMA in lines carrying the defect. The number of grains in ripe, treated tillers that contained high pI (malt, germination type) α-amylase isozymes was measured using an ELISA antibody kit highly specific for high pI isozymes. QTL analyses were conducted separately for each sowing, but results from both sowings were consistent and indicated that there was a highly significant (P < 0.001) QTL on the long arm of chromosome 7B (accounting for 31% of the variation in the first experiment), with Cranbrook contributing the higher value allele. A second QTL that accounted for 13% of the variation was found close to the centromere on chromosome 3B. Although it was less important than the QTL on 7B it was nevertheless still significant (P < 0.05).
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Muhu-Din Ahmed, Hafiz Ghulam, Muhammad Sajjad, Yawen Zeng, Muhammad Iqbal, Sultan Habibullah Khan, Aziz Ullah, and Malik Nadeem Akhtar. "Genome-Wide Association Mapping through 90K SNP Array for Quality and Yield Attributes in Bread Wheat against Water-Deficit Conditions." Agriculture 10, no. 9 (September 4, 2020): 392. http://dx.doi.org/10.3390/agriculture10090392.
Full textAbstract:
The decrease in water resources is a serious threat to food security world-wide. In this regard, a genome-wide association study (GWAS) was conducted to identify grain yield and quality-related genes/loci under normal and water-deficit conditions. Highly significant differences were exhibited among genotypes under both conditions for all studied traits. Water-deficit stress caused a reduction in grains yield and an increase in grains protein contents (GPC) and gluten contents (GLC). Population structure divided the 96 genotypes into four sub-populations. Out of 72 significant marker-trait associations (MTAs), 28 and 44 were observed under normal and water-deficit stress conditions, respectively. Pleiotropic loci (RAC875_s117925_244, BobWhite_c23828_341 and wsnp_CAP8_c334_304253) for yield and quality traits were identified on chromosomes 5A, 6B and 7B, respectively, under normal conditions. Under a water-deficit condition, the pleiotropic loci (Excalibur_c48047_90, Tdurum_contig100702_265 and BobWhite_c19429_95) for grain yield per plant (GYP), GPC and GLC were identified on chromosomes 3A, 4A and 7B, respectively. The pleiotropic loci (BS00063551_51 and RAC875_c28721_290) for GPC and GLC on chromosome 1B and 3A, respectively, were found under both conditions. Besides the validation of previously reported MTAs, some new MTAs were identified for flag leaf area (FLA), thousand grain weight (TGW), GYP, GPC and GLC under normal and water-deficit conditions. Twenty SNPs associated with the traits were mapped in the coding DNA sequence (CDS) of the respective candidate genes. The protein functions of the identified candidate genes were predicted and discussed. Isolation and characterization of the candidate genes, wherein, SNPs were mapped in CDS will result in discovering novel genes underpinning water-deficit tolerance in bread wheat.
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Belova, Tatiana, Lars Grønvold, Ajay Kumar, Shahryar Kianian, Xinyao He, Morten Lillemo, Nathan M. Springer, Sigbjørn Lien, Odd-Arne Olsen, and Simen R. Sandve. "Utilization of deletion bins to anchor and order sequences along the wheat 7B chromosome." Theoretical and Applied Genetics 127, no. 9 (August 19, 2014): 2029–40. http://dx.doi.org/10.1007/s00122-014-2358-z.
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McNeil, M. D., D. Diepeveen, R. Wilson, I. Barclay, R. McLean, B. Chalhoub, and R. Appels. "Haplotype analyses in wheat for complex traits: tracking the chromosome 3B and 7B regions associated with late maturity alpha amylase (LMA) in breeding programs." Crop and Pasture Science 60, no. 5 (2009): 463. http://dx.doi.org/10.1071/cp08340.
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The quantitative trait loci (QTLs) on chromosomes 7BL and 3BS from Halberd have been used as a major source of tolerance to late maturity α amylase (LMA) within Australian wheat breeding programs. New simple sequence repeat (SSR) markers identified from the sequencing of Bacterial Artificial Chromosome (BAC) clones from the wheat cv. Renan library, and known SSRs, were used to characterise these major QTLs. The reduction or elimination of the LMA defect in wheat cultivars is a major goal for wheat breeding programs and is confounded by the complexity in measuring the trait unambiguously. In this haplotyping study focussing on two significant chromosomal regions, markers and combinations of markers were investigated for their ability to discriminate between 39 Australian and Mexican wheat lines differing in levels of LMA. Genetic relationships among these wheat lines estimated by cluster analysis of molecular marker data were combined with phenotypic information in order to calibrate the genotypes of the wheat lines against their LMA phenotype. It was evident that some SSRs from the respective QTLs had greater discriminating power than others to identify LMA phenotypes. Discrimination was not, however, absolute and a statistical analysis of the data defined a risk factor associated with particular combinations of alleles, for use in early selection or backcrossing.
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Eguchi-Ishimae, Minenori, Mariko Eguchi, Zhouying Wu, Wen Ming, Hidehiko Iwabuki, Takeshi Inukai, Kanji Sugita, and Eiichi Ishii. "HMGA2 As a Potential Molecular Target in MLL-AF4 Positive Infant Acute Lymphoblastic Leukemia." Blood 124, no. 21 (December 6, 2014): 2244. http://dx.doi.org/10.1182/blood.v124.21.2244.2244.
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Abstract Leukemic cells of acute lymphoblastic leukemia (ALL) in infants are frequently characterised by chromosome translocations involving 11q23, resulting in the rearrangement of the mixed-lineage leukemia (MLL) gene and subsequent generation of MLL fusion gene. Among more than 50 genes which have been identified as the fusion partner of the MLL gene, fusion with AF4 is characteristically observed in infant ALL representing a hallmark of poor prognosis. Although recent progress of intensive chemotherapy with or without stem cell transplantation has improved its treatment outcome, the treatment is often accompanied by long-term side effects. Less toxic molecular targeting therapies are therefore necessary for infant ALL. We have previously reported that in infant ALL with MLL fusion gene, microRNA let-7b is significantly downregulated by DNA hypermethylation of its promoter region. The downregulation of let-7b is one of the consequences of oncogenic MLL fusion proteins contributing to leukemogenesis possibly through upregulation of let-7b-regulated target genes with oncogenic potential such as high mobility group AT-hook 2 (HMGA2). HMGA2 is a chromatin-remodelling factor, which alters chromatin architecture by binding to AT-rich regions in the DNA, either promoting or inhibiting the expression of its target genes. One of the targets of HMGA2 is CDKN2A gene which encodes 2 cell cycle regulators p16INK4A and p14ARF. This let-7b-HMGA2-CDKN2A axis regulates cellular growth and senescence of stem cells both in normal and pathological state such as cancer. We initially examined the expression of HMGA2 in leukemic cells obtained from 35 MLL-rearranged infant ALL patients (MLL-AF4, n = 26; MLL-AF9, n = 4; MLL-ENL, n = 5) using quantitative RT-PCR. As results, HMGA2 was highly expressed in most of the patients with MLL fusion gene, especially in MLL-AF4-positive cases, compared to those without the fusion. These results indicate that deregulation of let-7b-HMGA2 axis by MLL fusion may contribute to leukemogenesis and could be a possible target of molecular therapy against MLL-rearranged ALL. As let-7b is downregulated by promoter hypermethylation, demethylating agents such as 5-azacytidine could be applied to recover the expression of the gene in leukemic cells with MLL fusion gene. To test this possibility, leukemic cell lines with MLL-AF4 fusion gene were used. The administration of 5-azacytidine alone was able to restore the expression of suppressed let-7b as well as p16INK4A gene in the leukemic cells, but the effects was incomplete, showing persistent partial promoter methylation. In addition, the recovered expression disappeared when 5-azacytidine was removed. On the other hand, when HMGA2 inhibitor was combined with 5-azacytidine, the expression of let-7b was upregulated and sustained resulting in suppression of HMGA2 protein itself. This upregulation of let-7b and suppression of HMGA2 protein persisted even after the removal of 5-azacytidine, possibly through maintaining of the demethylating status by HMGA2 inhibitor. Inhibition of HMGA2 by either siRNA or HMGA2 inhibitor suppressed the growth of MLL-AF4-positive leukemic cells when analysed by MTT assay. The effects of HMGA2 inhibitor on cell growth inhibition became more prominent in combination with demethylating agent 5-azacytidine. Our results revealed the functional significance of let-7b and HMGA2 in controlling MLL-AF4-positive leukemic cell growth and the therapeutic potential of combining demethylating agent and the HMGA2 inhibitor in the treatment of MLL-AF4-positive ALL. Disclosures No relevant conflicts of interest to declare.
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Xu, Xiaodan, Wei Liu, Zhiyong Liu, Jieru Fan, and Yilin Zhou. "Mapping Powdery Mildew Resistance Gene pmYBL on Chromosome 7B of Chinese Wheat (Triticum aestivum L.) Landrace Youbailan." Plant Disease 104, no. 9 (September 2020): 2411–17. http://dx.doi.org/10.1094/pdis-01-20-0118-re.
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Chinese wheat landrace Youbailan has excellent resistance to powdery mildew caused by Blumeria graminis f. sp. tritici. In the present study, genetic analysis indicated that a recessive gene, tentatively designated pmYBL, was responsible for the powdery mildew resistance of Youbailan. pmYBL was located in the 695-to-715-Mb genomic region of chromosome 7BL, with 19 gene-linked single-nucleotide polymorphism (SNP) markers. It was flanked by SNP1-12 and SNP1-2 with genetic distances of 0.6 and 1.8 centimorgans, respectively. The disease reaction patterns of Youbailan and four cultivars (lines) carrying the powdery mildew (Pm) genes located on chromosome arm 7BL indicated that pmYBL may be allelic or closely linked to these genes. All of the SNP markers linked to pmYBL were diagnostic, indicating that these markers will be useful for pyramiding pmYBL using marker-assisted selection.
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Marzougui, Salem, Mohamed Kharrat, and Mongi ben Younes. "Marker-trait associations of yield related traits in bread wheat (Triticum aestivum L.) under a semi-arid climate." Czech Journal of Genetics and Plant Breeding 55, No. 4 (September 23, 2019): 138–45. http://dx.doi.org/10.17221/154/2018-cjgpb.
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Identifying QTLs (quantitative trait loci) that control yield related traits under a stressed environment is very useful for marker-assisted selection (MAS). Marker-trait associations (MTA) for several agro-morphological traits were performed with 130 Tunisian and exotic spring bread wheat (Triticum aestivum L.) accessions under a semi-arid climate in El Kef, Tunisia. Grain yield and other important traits were evaluated. A population structural analysis identified two sub populations. In total, 29 MTAs were detected at –log P ≥ 3 using an MLM (mixed linear model), and only 5 MTAs with –log P ≥ 4. The locus on chromosome 4A was detected to control the heading date accounting for up to 22% of the trait variance. Two other loci located on chromosomes 3B and 7B were found to be stable during the two cropping seasons and have a pleiotropic effect on the heading date, yield, internodes length and grain per spike. These two regions are candidates for further genetic analysis.
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Liu, Bao, Junkang Rong, Yingshan Dong, Fangpu Han, Zhenlan Liu, Mengyuan He, Baiqu Huang, and Shui Hao. "Microdissection of chromosome 7B of common wheat and cloning of low-copy specific DNA sequences." Chinese Science Bulletin 44, no. 7 (April 1999): 632–36. http://dx.doi.org/10.1007/bf03182725.
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Batey, I. L., M. J. Hayden, S. Cai, P. J. Sharp, G. B. Cornish, M. K. Morell, and R. Appels. "Genetic mapping of commercially significant starch characteristics in wheat crosses." Australian Journal of Agricultural Research 52, no. 12 (2001): 1287. http://dx.doi.org/10.1071/ar01053.
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Starch properties were measured on the doubled haploid progeny of 2 crosses, one between Cranbrook and Halberd and the other between CD87 and Katepwa. Properties studied included starch peak and final viscosity measured by Rapid Visco Analyser, starch granule size distribution measured by laser light scattering, starch gelatinisation temperature by differential scanning calorimetry, and flour swelling volume. In the Cranbrook Halberd cross (samples from 2 environments), a highly significant quantitative trait locus (QTL) was located on chromosome 4A for both starch peak viscosity and starch/flour swelling volume, centred around the Wx-B1 locus. In previous studies, this locus has been found to be linked to Japanese noodle quality. The increases in starch peak viscosity and flour swelling volume are derived from the Halberd parent, consistent with the fact that Halberd is null for the Wx-B1 locus on chromosome 4A and is missing the respective granule-bound starch synthase protein, whereas Cranbrook is a wheat line carrying the normal 3 Wx loci. The final starch viscosity also showed an association with the Wx-B1 locus. In the CD87 Katepwa cross, the progeny showed an association between peak viscosity and a marker on chromosome 7A. This appeared to be near the Wx-A1 locus. In some experiments, flour viscosity showed a highly significant QTL on chromosome 7B, apparently at the same locus as the late maturity - amylase derived from the Cranbrook parent. Starch gelatinisation onset temperature indicated a significant QTL on chromosomes 2B and 7A (LOD = 2.58 and 3.66, respectively, in interval analyses). Starch gelatinisation peak temperatures indicated a QTL on chromosome 7A, which, although not in the significant (P = 0.05) class based on regression analyses, indicated a LOD score of 3.06 in interval analyses. Heat of gelatinisation (H) indicated a suggestive QTL (LRS = 14.5 with a threshold of 14.7 for P < 0.05, LOD = 2.65 for interval analysis), on chromosome 4A, at the Wx-B1 locus with an increased effect coming from the Halberd parent. The A:B granule ratio analysis indicated a significant QTL on chromosome 4B, but this was not observed in all environments and may be due to the fact that the QTL corresponded to the position of a major QTL controlling plant growth.
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Batey, I. L., M. J. Hayden, S. Cai, P. J. Sharp, G. B. Cornish, M. K. Morell, and R. Appels. "Corrigendum to: Genetic mapping of commercially significant starch characteristics in wheat crosses." Australian Journal of Agricultural Research 53, no. 9 (2002): 1083. http://dx.doi.org/10.1071/ar01053_co.
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Starch properties were measured on the doubled haploid progeny of 2 crosses, one between Cranbrook and Halberd and the other between CD87 and Katepwa. Properties studied included starch peak and final viscosity measured by Rapid Visco Analyser, starch granule size distribution measured by laser light scattering, starch gelatinisation temperature by differential scanning calorimetry, and flour swelling volume. In the Cranbrook Halberd cross (samples from 2 environments), a highly significant quantitative trait locus (QTL) was located on chromosome 4A for both starch peak viscosity and starch/flour swelling volume, centred around the Wx-B1 locus. In previous studies, this locus has been found to be linked to Japanese noodle quality. The increases in starch peak viscosity and flour swelling volume are derived from the Halberd parent, consistent with the fact that Halberd is null for the Wx-B1 locus on chromosome 4A and is missing the respective granule-bound starch synthase protein, whereas Cranbrook is a wheat line carrying the normal 3 Wx loci. The final starch viscosity also showed an association with the Wx-B1 locus. In the CD87 Katepwa cross, the progeny showed an association between peak viscosity and a marker on chromosome 7A. This appeared to be near the Wx-A1 locus. In some experiments, flour viscosity showed a highly significant QTL on chromosome 7B, apparently at the same locus as the late maturity - amylase derived from the Cranbrook parent. Starch gelatinisation onset temperature indicated a significant QTL on chromosomes 2B and 7A (LOD = 2.58 and 3.66, respectively, in interval analyses). Starch gelatinisation peak temperatures indicated a QTL on chromosome 7A, which, although not in the significant (P = 0.05) class based on regression analyses, indicated a LOD score of 3.06 in interval analyses. Heat of gelatinisation (H) indicated a suggestive QTL (LRS = 14.5 with a threshold of 14.7 for P < 0.05, LOD = 2.65 for interval analysis), on chromosome 4A, at the Wx-B1 locus with an increased effect coming from the Halberd parent. The A:B granule ratio analysis indicated a significant QTL on chromosome 4B, but this was not observed in all environments and may be due to the fact that the QTL corresponded to the position of a major QTL controlling plant growth.
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Giura, A., L. Conţescu, P. Mustăţea, G. Ittu, and N. Săulescu. "Effects of chromosome 7B genes on grain protein concentration, yield and earliness in wheat (Triticum aestivumL.)." Cereal Research Communications 36, no. 4 (December 2008): 669–76. http://dx.doi.org/10.1556/crc.36.2008.4.16.
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Singh, Pawan Kumar, Sukhwinder Singh, Zhiying Deng, Xinyao He, Zakaria Kehel, and Ravi Prakash Singh. "Characterization of QTLs for Seedling Resistance to Tan Spot and Septoria Nodorum Blotch in the PBW343/Kenya Nyangumi Wheat Recombinant Inbred Lines Population." International Journal of Molecular Sciences 20, no. 21 (October 31, 2019): 5432. http://dx.doi.org/10.3390/ijms20215432.
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Tan spot (TS) and Septoria nodorum blotch (SNB) induced by Pyrenophora tritici-repentis and Parastagonospora nodorum, respectively, cause significant yield losses and adversely affect grain quality. The objectives of this study were to decipher the genetics and map the resistance to TS and SNB in the PBW343/Kenya Nyangumi (KN) population comprising 204 F6 recombinant inbred lines (RILs). Disease screening was performed at the seedling stage under greenhouse conditions. TS was induced by P. tritici-repentis isolate MexPtr1 while SNB by P. nodorum isolate MexSN1. Segregation pattern of the RILs indicated that resistance to TS and SNB in this population was quantitative. Diversity Array Technology (DArTs) and simple sequence repeats (SSRs) markers were used to identify the quantitative trait loci (QTL) for the diseases using inclusive composite interval mapping (ICIM). Seven significant additive QTLs for TS resistance explaining 2.98 to 23.32% of the phenotypic variation were identified on chromosomes 1A, 1B, 5B, 7B and 7D. For SNB, five QTLs were found on chromosomes 1A, 5A, and 5B, explaining 5.24 to 20.87% of the phenotypic variation. The TS QTL on 1B chromosome coincided with the pleiotropic adult plant resistance (APR) gene Lr46/Yr29/Pm39. This is the first report of the APR gene Lr46/Yr29/Pm39 contributing to TS resistance.
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Gong, Caiyan, Shuanghe Cao, Renchun Fan, Bo Wei, Guiping Chen, Xianping Wang, Yiwen Li, and Xiangqi Zhang. "Identification and Phylogenetic Analysis of a CC-NBS-LRR Encoding Gene Assigned on Chromosome 7B of Wheat." International Journal of Molecular Sciences 14, no. 8 (July 24, 2013): 15330–47. http://dx.doi.org/10.3390/ijms140815330.
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Leonova, Irina N., Ekaterina S. Skolotneva, Elena A. Orlova, Olga A. Orlovskaya, and Elena A. Salina. "Detection of Genomic Regions Associated with Resistance to Stem Rust in Russian Spring Wheat Varieties and Breeding Germplasm." International Journal of Molecular Sciences 21, no. 13 (July 1, 2020): 4706. http://dx.doi.org/10.3390/ijms21134706.
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Stem rust caused by Puccinia graminis f. sp. tritici Eriks. is a dangerous disease of common wheat worldwide. Development and cultivation of the varieties with genetic resistance is one of the most effective and environmentally important ways for protection of wheat against fungal pathogens. Field phytopathological screening and genome-wide association study (GWAS) were used for assessment of the genetic diversity of a collection of spring wheat genotypes on stem rust resistance loci. The collection consisting of Russian varieties of spring wheat and introgression lines with alien genetic materials was evaluated over three seasons (2016, 2017 and 2018) for resistance to the native population of stem rust specific to the West Siberian region of Russia. The results indicate that most varieties displayed from moderate to high levels of susceptibility to P. graminis; 16% of genotypes had resistance or immune response. In total, 13,006 single-nucleotide polymorphism (SNP) markers obtained from the Infinium 15K array were used to perform genome-wide association analysis. GWAS detected 35 significant marker-trait associations (MTAs) with SNPs located on chromosomes 1A, 2A, 2B, 3B, 5A, 5B, 6A, 7A and 7B. The most significant associations were found on chromosomes 7A and 6A where known resistance genes Sr25 and Sr6Ai = 2 originated from Thinopyrum ssp. are located. Common wheat lines containing introgressed fragments from Triticum timopheevii and Triticum kiharae were found to carry Sr36 gene on 2B chromosome. It has been suggested that the quantitative trait loci (QTL) mapped to the chromosome 5BL may be new loci inherited from the T. timopheevii. It can be inferred that a number of Russian wheat varieties may contain the Sr17 gene, which does not currently provide effective protection against pathogen. This is the first report describing the results of analysis of the genetic factors conferring resistance of Russian spring wheat varieties to stem rust.
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Huang, Sheng-He, Yu-Hua Chen, Qi Fu, Monique Stins, Ying Wang, Carol Wass, and Kwang Sik Kim. "Identification and Characterization of an Escherichia coli Invasion Gene Locus, ibeB, Required for Penetration of Brain Microvascular Endothelial Cells." Infection and Immunity 67, no. 5 (May 1, 1999): 2103–9. http://dx.doi.org/10.1128/iai.67.5.2103-2109.1999.
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ABSTRACT Escherichia coli K1 is the most common gram-negative organism causing neonatal meningitis, but the mechanism by whichE. coli K1 crosses the blood-brain barrier is incompletely understood. We have previously described the cloning and molecular characterization of a determinant, ibeA (also called ibe10), from the chromosome of an invasive cerebrospinal fluid isolate of E. coli K1 strain RS218 (O18:K1:H7). Here we report the identification of another chromosomal locus, ibeB, which allows RS218 to invade brain microvascular endothelial cells (BMEC). The noninvasive TnphoA mutant 7A-33 exhibited <1% the invasive ability of the parent strain in vitro in BMEC and was significantly less invasive in the central nervous system in the newborn rat model of hematogenousE. coli meningitis than the parent strain. The TnphoA insert with flanking sequences was cloned and sequenced. A 1,383-nucleotide open reading frame (ORF) encoding a 50-kDa protein was identified and termed ibeB. This ORF was found to be 97% identical to a gene encoding a 50-kDa hypothetical protein (p77211) and located in the 13-min region of the E. coli K-12 genome. However, no homology was observed between ibeB and other known invasion genes when DNA and protein databases in GenBank were searched. Like the TnphoA insertion mutant 7A-33, an isogenic ibeBdeletion mutant (IB7D5) was unable to invade BMEC. A 7.0-kb locus containing ibeB was isolated from a LambdaGEM-12 genomic library of E. coli RS218 and subcloned into a pBluescript KS vector (pKS7-7B). pKS7-7B was capable of completely restoring the BMEC invasion of the noninvasive TnphoA mutant 7A-33 and the ibeB deletion mutant IB7D5 to the level of the parent strain. More importantly, the ibeB deletion mutant IB7D5 was fully complemented by pFN476 carrying the ibeB ORF (pFN7C), indicating thatibeB is required for E. coli K1 invasion of BMEC. Taken together, these findings indicate that severalE. coli determinants, including ibeA andibeB, contribute to crossing of the blood-brain barrier.
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Raman, Harsh, Benjamin Stodart, Peter R. Ryan, Emmanuel Delhaize, Livinus Emebiri, Rosy Raman, Neil Coombes, and Andrew Milgate. "Genome-wide association analyses of common wheat (Triticum aestivum L.) germplasm identifies multiple loci for aluminium resistanceThis article is one of a selection of papers from the conference “Exploiting Genome-wide Association in Oilseed Brassicas: a model for genetic improvement of major OECD crops for sustainable farming”." Genome 53, no. 11 (November 2010): 957–66. http://dx.doi.org/10.1139/g10-058.
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Aluminium (Al3+) toxicity restricts productivity and profitability of wheat ( Triticum aestivum L.) crops grown on acid soils worldwide. Continued gains will be obtained by identifying superior alleles and novel Al3+ resistance loci that can be incorporated into breeding programs. We used association mapping to identify genomic regions associated with Al3+ resistance using 1055 accessions of common wheat from different geographic regions of the world and 178 polymorphic diversity arrays technology (DArT) markers. Bayesian analyses based on genetic distance matrices classified these accessions into 12 subgroups. Genome-wide association analyses detected markers that were significantly associated with Al3+ resistance on chromosomes 1A, 1B, 2A, 2B, 2D, 3A, 3B, 4A, 4B, 4D, 5B, 6A, 6B, 7A, and 7B. Some of these genomic regions correspond to previously identified loci for Al3+ resistance, whereas others appear to be novel. Among the markers targeting TaALMT1 (the major Al3+-resistance gene located on chromosome 4D), those that detected alleles in the promoter explained most of the phenotypic variance for Al3+ resistance, which is consistent with this region controlling the level of TaALMT1 expression. These results demonstrate that genome-wide association mapping cannot only confirm known Al3+-resistance loci, such as those on chromsomes 4D and 4B, but they also highlight the utility of this technique in identifying novel resistance loci.
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Rehman Arif, Mian Abdur, Fauzia Attaria, Sajid Shokat, Saba Akram, Muhammad Qandeel Waheed, Anjuman Arif, and Andreas Börner. "Mapping of QTLs Associated with Yield and Yield Related Traits in Durum Wheat (Triticum durum Desf.) Under Irrigated and Drought Conditions." International Journal of Molecular Sciences 21, no. 7 (March 30, 2020): 2372. http://dx.doi.org/10.3390/ijms21072372.
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Global durum wheat consumption (Triticum durum Desf.) is ahead of its production. One reason for this is abiotic stress, e.g., drought. Breeding for resistance to drought is complicated by the lack of fast, reproducible screening techniques and the inability to routinely create defined and repeatable water stress conditions. Here, we report the first analysis of dissection of yield and yield-related traits in durum wheat in Pakistan, seeking to elucidate the genetic components of yield and agronomic traits. Analysis of several traits revealed a total of 221 (160 with logarithm of odds (LOD) > 2 ≤ 3 and 61 with LOD > 3) quantitative trait loci (QTLs) distributed on all fourteen durum wheat chromosomes, of which 109 (78 with LOD > 2 ≤ 3 and 31 with LOD > 3) were observed in 2016-17 (S1) and 112 (82 with LOD > 2 ≤ 3 and 30 with LOD > 3) were observed in 2017-18 (S2). Allelic profiles of yield QTLs on chromosome 2A and 7B indicate that allele A of Xgwm895 and allele B of Xbarc276 can enhance the Yd up to 6.16% in control and 5.27% under drought. Moreover, if combined, a yield gain of up to 11% would be possible.
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Iannucci, Anna, Daniela Marone, Maria Anna Russo, Pasquale De Vita, Vito Miullo, Pina Ferragonio, Antonio Blanco, Agata Gadaleta, and Anna Maria Mastrangelo. "Mapping QTL for Root and Shoot Morphological Traits in a Durum Wheat × T. dicoccumSegregating Population at Seedling Stage." International Journal of Genomics 2017 (2017): 1–17. http://dx.doi.org/10.1155/2017/6876393.
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A segregating population of 136 recombinant inbred lines derived from a cross between the durum wheat cv. “Simeto” and theT. dicoccumaccession “Molise Colli” was grown in soil and evaluated for a number of shoot and root morphological traits. A total of 17 quantitative trait loci (QTL) were identified for shoot dry weight, number of culms, and plant height and for root dry weight, volume, length, surface area, and number of forks and tips, on chromosomes 1B, 2A, 3A, 4B, 5B, 6A, 6B, and 7B. LODs were 2.1 to 21.6, with percent of explained phenotypic variability between 0.07 and 52. Three QTL were mapped to chromosome 4B, one of which corresponds to theRht-B1locus and has a large impact on both shoot and root traits (LOD 21.6). Other QTL that have specific effects on root morphological traits were also identified. Moreover, meta-QTL analysis was performed to compare the QTL identified in the “Simeto” × “Molise Colli” segregating population with those described in previous studies in wheat, with three novel QTL defined. Due to the complexity of phenotyping for root traits, further studies will be helpful to validate these regions as targets for breeding programs for optimization of root function for field performance.