Academic literature on the topic 'Plant improvement (selection, breeding and genetic engineering)'
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Journal articles on the topic "Plant improvement (selection, breeding and genetic engineering)"
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Griesbach, R. J., P. Semeniuk M. Roh, and R. H. Lawson. "Tissue Culture in the Improvement of Eustoma." HortScience 23, no. 4 (August 1988): 658–791. http://dx.doi.org/10.21273/hortsci.23.4.658.
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Abstract Genetic engineering offers promise in the development of new plant forms. Alterations in plant size, branching, flower color and form, disease resistance, and many other factors may occur in plants produced by new technologies without sexual breeding and selection. Many desirable characteristics, not always observed in plants developed by breeding, are often expressed in plants engineered by tissue culture technology. Some of the plants showing these different new trait(s) also can be reproduced uniformly from seed, thus indicating genetic transmission of the new trait(s). This exciting approach to plant modification has been used to develop new forms of lisianthus.
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Mwamahonje, Andekelile, Deusdedit Kilambo, Leon Mrosso, and Tileye Feyissa. "Prospects of Biotechnology in Grape Breeding." JOURNAL OF ADVANCES IN AGRICULTURE 5, no. 1 (October 19, 2015): 565–73. http://dx.doi.org/10.24297/jaa.v5i1.4510.
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Genetic improvement of grape cultivars to obtain high quality wine and table grape varieties by conventional breeding methods has been difficult and time consuming. The elite grape varieties developed by conventional breeding techniques have less resistance to fungal and bacterial diseases, drought, quality and yield per plant. Breeding programs of grapes are difficult due to lack of true bred from seed and few traits of importance. Though most grapes constitute large number of genes, they have less effect in tolerating biotic and abiotic stresses. Genetic improvement of grapevine (Vitis vinifera L.) through application of biotechnological techniques provide new strategies in grape breeding programs based on rapid selection or induction of desired traits by marker assisted breeding, genetic engineering and plant tissue culture. This review paper therefore, aims to discuss biotechnological techniques proposed for improvement of grape breeding.
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Temesgen, Begna. "Speed breeding to accelerate crop improvement." International Journal of Agricultural Science and Food Technology 8, no. 2 (June 2, 2022): 178–86. http://dx.doi.org/10.17352/2455-815x.000161.
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Global food security has become a major issue as the human population grows and the environment changes, with the current rate of improvement of several important crops inadequate to meet future demand. Crop plants have extended generation times, which contributes to the slow rate of progress. However, speed breeding has revolutionized the entire world by reducing generation time and speeding up breeding and research programs to improve crop varieties. In the absence of an integrated pre-breeding program, breeding new and high-performing cultivars with market-preferred traits can take more than ten years. After the first cross with parental genotypes, a large amount of time, space, and resources are committed to the selection and genetic advancement stages during the early stages of breeding. Speed breeding has the ability to shorten the time it takes to develop, market, and commercialize cultivars. Crop improvement in the face of a fast-changing environment and an ever-increasing human population is a major concern for scientists around the world. Current crop enhancement projects are progressing at a rate that is insufficient to meet food demand. Crop redesign is urgently needed for climate resilience, as well as long-term yield and nutrition. Crop progress is slowed significantly by the long generation time required by crop plants during the breeding process. Speed breeding is now being used on a large scale to shorten generation time and support multiple crop generations per year as a solution in this approach. Researchers are now using an integrated approach to improve breeding efficiency, combining speed breeding with current plant breeding and genetic engineering methods. Speed breeding is a promising approach for achieving nutritional security and sustainable agriculture by shortening breeding cycles for food and industrial crop enhancement. Speed breeding is a methodology that allows plant breeders to improve crop production by adjusting temperature, light duration, and intensity to boost plant development. It uses an artificial source of light, which is kept on continuously, to activate the photosynthetic process, which leads to growth and reproduction much earlier than normal. This will assist in meeting the demands of the future’s rising population. This can be accomplished using a variety of technologies, including genotyping, marker-assisted selection, high throughput phenotyping; gene editing, genomic selection, and re-domestication, all of which can be combined with speed breeding to allow plant breeders to keep up with a changing climate and growing human population.
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Šušek, Andrej. "Perspectives of Christmas rose (Helleborus niger L.) genetic improvement." Agricultura 13, no. 1-2 (December 1, 2016): 11–19. http://dx.doi.org/10.1515/agricultura-2017-0003.
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Abstract The Christmas rose is becoming a very important ornamental plant on the market. It is relatively new to intensive production technologies. The number of genetically-improved varieties on the market is limited, and many of the old cultivars are no longer available because of slow and economically unfeasible vegetative propagation. In the future, its genetic improvement will probably become inevitable. New cultivars will have to satisfy the specific requirements of the market and producers as well as strict environmental policy. In order to obtain new cultivars it will be necessary to evaluate the existing germplasm and apply an adequate genetic breeding approach. There are seven main possibilities of creating new varieties: the use of natural variation associated with seed germination, population approach based on recurrent selection, individual selection based on specific genetic combinations, the creation of inbred lines and the formation of hybrids, interspecific hybridisation, mutagenesis and genetic engineering. Molecular markers can be very helpful during the breeding process. They can be used in order to study genetic relationships amongst populations, ecotypes, varieties, and hybrids.
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Kumar, Ravinder, Nand K. Sharma, Savita Meena, and Adithya P. Balakrishnan. "Mutation Breeding: A Way Forward for Genetic Improvement in Mungbean." INTERNATIONAL JOURNAL OF PLANT AND ENVIRONMENT 7, no. 04 (December 31, 2021): 255–62. http://dx.doi.org/10.18811/ijpen.v7i04.3.
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Mungbean is a major food leguminous crop mainly cultivated in Asia. It is famous for its high protein, carbohydrate, and nutritional content. With the help of microorganisms located in their root nodules, the crop also maintain soil fertility through biological nitrogen fixation. This not only allows them to meet their own nitrogen needs, but it also improves the production of succeeding crops. One of the prerequisites for crop improvement is the availability of genetic variability. The capability to select improved genotypes in mungbean is limited by a lack of necessary diversity. Chemical and physical mutagens are frequently employed in Plant Mutation Breeding to boost crop productivity and resistance to diseases, insects, drought, and salt by creating genetic variability in crop plants. Mungbean is an early maturing crop often cultivated on low-fertility land with minimal inputs. In the case of these crops, the selection pressure has been focused on stress adaptation rather than yield. As a result, improving the genetics of such crops to increase yield necessitates genetic reconstitution to generate diverse plant types. Induced mutations can contribute to the regeneration and restoration of diversity that has been lost during the evolutionary process because of various pressures or adaptations. Thus, induced mutation or mutation breeding has a lot of potential for improving traditional agricultural crops like mungbean. In this paper, we look at many forms of mutations identified in mungbean crops by various scientists.
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Han, Fengqing, Yumei Liu, Zhiyuan Fang, Limei Yang, Mu Zhuang, Yangyong Zhang, Honghao Lv, Yong Wang, Jialei Ji, and Zhansheng Li. "Advances in Genetics and Molecular Breeding of Broccoli." Horticulturae 7, no. 9 (September 3, 2021): 280. http://dx.doi.org/10.3390/horticulturae7090280.
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Broccoli (Brassica oleracea L. var. italica) is one of the most important vegetable crops cultivated worldwide. The market demand for broccoli is still increasing due to its richness in vitamins, anthocyanins, mineral substances, fiber, secondary metabolites and other nutrients. The famous secondary metabolites, glucosinolates, sulforaphane and selenium have protective effects against cancer. Significant progress has been made in fine-mapping and cloning genes that are responsible for important traits; this progress provides a foundation for marker-assisted selection (MAS) in broccoli breeding. Genetic engineering by the well-developed Agrobacterium tumefaciens-mediated transformation in broccoli has contributed to the improvement of quality; postharvest life; glucosinolate and sulforaphane content; and resistance to insects, pathogens and abiotic stresses. Here, we review recent progress in the genetics and molecular breeding of broccoli. Future perspectives for improving broccoli are also briefly discussed.
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Penna, Suprasanna, and Shri Mohan Jain. "Fruit Crop Improvement with Genome Editing, In Vitro and Transgenic Approaches." Horticulturae 9, no. 1 (January 3, 2023): 58. http://dx.doi.org/10.3390/horticulturae9010058.
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Fruit species contribute to nutritional and health security by providing micronutrients, antioxidants, and bioactive phytoconstituents, and hence fruit-based products are becoming functional foods presently and for the future. Although conventional breeding methods have yielded improved varieties having fruit quality, aroma, antioxidants, yield, and nutritional traits, the threat of climate change and need for improvement in several other traits such as biotic and abiotic stress tolerance and higher nutritional quality has demanded complementary novel strategies. Biotechnological research in fruit crops has offered immense scope for large-scale multiplication of elite clones, in vitro, mutagenesis, and genetic transformation. Advanced molecular methods, such as genome-wide association studies (GWAS), QTLomics, genomic selection for the development of novel germplasm having functional traits for agronomic and nutritional quality, and enrichment of bioactive constituents through metabolic pathway engineering and development of novel products, are now paving the way for trait-based improvement for developing genetically superior varieties in fruit plant species for enhanced nutritional quality and agronomic performance. In this article, we highlight the applications of in vitro and molecular breeding approaches for use in fruit breeding.
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Gaba, Yashika, Ashwani Pareek, and Sneh Lata Singla-Pareek. "Raising Climate-Resilient Crops: Journey From the Conventional Breeding to New Breeding Approaches." Current Genomics 22, no. 6 (December 30, 2021): 450–67. http://dx.doi.org/10.2174/1389202922666210928151247.
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Background: In order to meet the demands of the ever-increasing human population, it has become necessary to raise climate-resilient crops. Plant breeding, which involves crossing and selecting superior gene pools, has contributed tremendously towards achieving this goal during the past few decades. The relatively newer methods of crop improvement based on genetic engineering are relatively simple, and targets can be achieved in an expeditious manner. More recently emerged genome editing technique using CRISPR has raised strong hopes among plant scientists for precise integration of valuable traits and removal of undesirable ones. Conclusion: Genome editing using Site-Specific Nucleases (SSNs) is a good alternative to the plant breeding and genetic engineering approaches as it can modify the genomes specifically and precisely at the target site in the host genome. Another added advantage of the genome editing approach is the simpler biosafety regulations that have been adopted by many countries for commercialization of the products thus generated. This review provides a critical assessment of the available methods for improving the stress tolerance in crop plants. Special emphasis has been given on genome editing approach in light of the diversity of tools, which are being discovered on an everyday basis and the practical applications of the same. This information will serve as a beginner’s guide to initiate the crop improvement programs as well as giving technical insight to the expert to plan the research strategically to tackle even multigenic traits in crop plants.
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Kulkarni, R. N., K. Baskaran, and Tripta Jhang. "Breeding medicinal plant, periwinkle [Catharanthus roseus(L) G. Don]: a review." Plant Genetic Resources 14, no. 4 (May 2, 2016): 283–302. http://dx.doi.org/10.1017/s1479262116000150.
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AbstractPeriwinkle [Catharanthus roseus(L) G. Don] has become one of the very extensively investigated medicinal plants after the discovery of two powerful anti-cancer alkaloids, vinblastine and vincristine, in its leaves more than 50 years ago. These alkaloidal drugs are still in clinical use. Also, periwinkle is still the only source of these alkaloids and their precursors, catharanthine and vindoline. Low concentrations of these alkaloids in the plant and, therefore, high costs of their extraction have led to tremendous efforts towards understanding their biosynthesis and exploration of alternate ways of their production such as, chemical synthesis, cell, tissue and hairy root cultures, and metabolic engineering of heterologous organisms. Literature on this plant is quite voluminous, with an average of about 80 publications per year during last three decades (1985–2015). Nearly 60% of these publications are on physiology, biochemistry, cell and tissue culture, phytochemistry, metabolic and genetic engineering aspects. In spite of these efforts, an economically viable alternative to field-grown periwinkle plants as a source of these alkaloids has not yet been found. Biosynthesis ofC. roseusalkaloids is a complex process involving many genes, enzymes, regulators, inter- and intra-cellular transporters, cell types, organelles and tissues and its current understanding is still considered to be incomplete to produceC. roseusalkaloids through metabolic engineering/synthetic biology. Till such time, breeding periwinkle varieties with higher concentrations of anti-cancer alkaloids for cultivation can be an alternate approach to meet the demand for these alkaloids and reduce their costs. While literature on cell and tissue culture, phytochemistry, metabolic and genetic engineering aspects of periwinkle has been reviewed periodically, crop production and plant breeding aspects have received little attention. In this paper, an attempt has been made to bring together published information on genetics and breeding of periwinkle as a medicinal plant. Some probable constraints which may have hindered taking up periwinkle breeding are identified. Initially, quite a few attempts have been made at genetic improvement of periwinkle through induced polyploidy, and subsequently through induced mutagenesis. Mutations, both natural and induced, provide a valuable resource for use in breeding and in functional and reverse genomics research. It is only during last 6–7 years, genetic diversity has been assessed using molecular markers and very recently molecular markers have been identified for marker-assisted selection for alkaloid yield.
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Trono, Daniela, and Nicola Pecchioni. "Candidate Genes Associated with Abiotic Stress Response in Plants as Tools to Engineer Tolerance to Drought, Salinity and Extreme Temperatures in Wheat: An Overview." Plants 11, no. 23 (December 2, 2022): 3358. http://dx.doi.org/10.3390/plants11233358.
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Wheat represents one of the most important staple food crops worldwide and its genetic improvement is fundamental to meeting the global demand of the growing population. However, the environmental stresses, worsened by climate change, and the increasing deterioration of arable land make it very difficult to fulfil this demand. In light of this, the tolerance of wheat to abiotic stresses has become a key objective of genetic improvement, as an effective strategy to ensure high yields without increasing the cultivated land. Genetic erosion related to modern agriculture, whereby elite, high-yielding wheat varieties are the product of high selection pressure, has reduced the overall genetic diversity, including the allelic diversity of genes that could be advantageous for adaptation to adverse environmental conditions. This makes traditional breeding a less effective or slower approach to generating new stress-tolerant wheat varieties. Either mining for the diversity of not-adapted large germplasm pools, or generating new diversity, are the mainstream approaches to be pursued. The advent of genetic engineering has opened the possibility to create new plant variability and its application has provided a strong complement to traditional breeding. Genetic engineering strategies such as transgenesis and genome editing have then provided the opportunity to improve environmental tolerance traits of agronomic importance in cultivated species. As for wheat, several laboratories worldwide have successfully produced transgenic wheat lines with enhanced tolerance to abiotic stresses, and, more recently, significant improvements in the CRISPR/Cas9 tools available for targeted variations within the wheat genome have been achieved. In light of this, the present review aims to provide successful examples of genetic engineering applications for the improvement of wheat adaptation to drought, salinity and extreme temperatures, which represent the most frequent and most severe events causing the greatest losses in wheat production worldwide.
Dissertations / Theses on the topic "Plant improvement (selection, breeding and genetic engineering)"
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Stewart, Alan V. "Plant breeding aspects of ryegrasses (Lolium sp.) infected with endophytic fungi." Phd thesis, University of Canterbury. Lincoln College, 1987. http://theses.lincoln.ac.nz/public/adt-NZLIU20071005.172250/.
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Some aspects of the presence of systemic endophytic fungi in agriculturally important New Zealand grasses were studied in relation to plant breeding. Seedling resistance to adult Argentine stem weevil feeding in perennial ryegrass, Italian ryegrass and tall fescue was found to be related to the presence of their respective Acremonium endophytes in the seed rather than to plant genetic resistance. In addition a study of perennial ryegrass revealed that this resistance was independent of endophyte viability. The seedling resistance conferred by the endophyte of Italian ryegrass was found to be beneficial for field establishment. This endophyte differs from that in perennial ryegrass and tall fescue in that it does not confer resistance to Argentine stem weevil on mature plants, but only on seedlings. The extent of plant genetic seedling tolerance to adult Argentine stem weevil feeding was limited to broad inter-specific differences, with tall fescue more tolerant than perennial ryegrass and both of these more tolerant than Italian ryegrass. This ranking corresponds with previous observations on feeding preference on mature plants. A study of factors affecting the concentration of endophyte mycelia in infected seed of perennial ryegrass revealed that plant genetic factors had little effect. The major factors studied were: 1) the endophyte concentration in the maternal parent plant directly influenced the endophyte concentration in the seed. 2) nitrogen fertilizer applications to a seed crop reduced the concentration of mycelia in the seed, with earlier applications having a greater effect. 3) application of the fungicide propiconazole (Tilt) to a seed crop reduced the endophyte concentration in the seed. 4) the endophyte concentration in the seed was found to directly influence the endophyte concentration in seedlings, six month old plants and that of seed harvested from a first year seed crop. As there have been no previous reports of tetraploid perennial ryegrass cultivars with endophyte an experiment was conducted to determine if these could be developed by the standard procedure of colchicine treatment. The results revealed that endophyte was retained following colchicine treatment.
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Childerhouse, Emma. "The effect of a natural plant extract and synthetic plant growth regulators on growth, quality and endogenous hormones of Actinidia chinensis and Actinidia deliciosa fruit : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticultural Science at Massey University, New Zealand." Massey University, 2009. http://hdl.handle.net/10179/1052.
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Kiwifruit are of huge economic importance for New Zealand representing 29 percent of total horticultural exports. Fruit size is the biggest determinant of what consumers are willing to pay, and there is also a positive relationship between consumer preference for flavour and percentage dry matter. The two main cultivars exported from New Zealand are Actinidia chinensis ‘Hort 16A’ (gold kiwifruit) and A. deliciosa ‘Hayward’ (green kiwifruit). Under current commercial practice the only product allowed for use on kiwifruit to increase fruit size in New Zealand is Benefit®. Benefit® has been shown to induce different results when applied to A. chinensis and A. deliciosa, whereas synthetic plant growth regulators such as the cytokinin-like substance N-(2- chloro-4-pyridyl)-N’-phenylurea (CPPU) have been found to promote similar increases in fresh weight of fruit in both cultivars. Final fruit size is determined by both cell division and cell enlargement. It was been shown that fresh weight can be increased in both of the major Actinidia cultivars even though their physiology differs. Hormonal control of fruit size in relation to cell division and cell enlargement phases of fruit growth was studied in both A. chinensis and A. deliciosa. CPPU was applied to both cultivars in a growth response experiment where fruit were collected throughout the growing season. The objective of this experiment was to create growth curves, to compare and contrast the effect on A. chinensis and A. deliciosa, and to provide material for hormone analysis. Application of CPPU was found to significantly increase the fresh weight of both A. chinensis and A. deliciosa fruit (46.98 and 31.34 g increases respectively), and alter the ratio of inner and outer pericarps of A. chinensis fruit. CPPU and Benefit® were applied individually and together to both cultivars. It was found that only A. chinesis fruit were affected by the application of Benefit®; fresh weight was increased by 26.38 g, and percentage dry matter was significantly reduced. There was a statistically significant (p < 0.05) interaction between CPPU and Benefit® when applied to A. chinensis. 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) was applied to A. deliciosa on two application dates at three concentrations and was found to decrease fresh weight of fruit, but significantly increase percentage dry matter regardless of application date or concentration. Lastly CPPU and 1-naphthalene acetic acid (NAA) were applied to A. deliciosa at two application dates and in all combinations. Application date affected the response to both a low concentration of CPPU and NAA. A synergistic interaction was observed when CPPU was applied early plus NAA late (CPPU early (4.53 g increase) plus NAA late (13.29 g) < CPPU early plus NAA late (33.85 g). Finally endogenous hormone content was studied. Methods were developed and tested for the simultaneous analysis of both indole-3-acetic acid (IAA) and cytokinins. Freeze dried fruit were purified using Waters Sep-pak® cartridges and Oasis® columns then IAA was quantified by high pressure liquid chromatography. Preliminary results indicate a correlation between application of CPPU and endogenous IAA, high concentrations of IAA correlated well with periods of rapid fruit growth particularly for CPPU treated fruit.
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Raikar, S. V. "Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression." Diss., Lincoln University, 2007. http://hdl.handle.net/10182/301.
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Lolium perenne is one of the most important forage crops globally and in New Zealand. Lotus corniculatus is a dicotyledonous forage that contains valuable traits such as high levels of condensed tannins, increased digestibility, and high nitrogen fixing abilities. However, conventional breeding between these two forage crops is impossible due to their markedly different taxonomic origin. Protoplast fusion (somatic hybridisation) provides an opportunity for gene introgression between these two species. This thesis describes the somatic hybridisation, the regeneration and the molecular analysis of the putative somatic hybrid plants obtained between L. perenne and L. corniculatus. Callus and cell suspensions of different cultivars of L. perenne were established from immature embryos and plants were regenerated from the callus. Of the 10 cultivars screened, cultivars Bronsyn and Canon had the highest percentage of callus induction at 36% each on 5 mg/L 2,4-D. Removal of the palea and lemma which form the seed coat was found to increase callus induction ability of the embryos. Plant regeneration from the callus was achieved when the callus was plated on LS medium supplemented with plant growth regulators at different concentrations. Variable responses to shoot regeneration was observed between the different cultivars with the cv Kingston having the lowest frequency of shoot formation (12%). Different factors affecting the protoplast isolation of L. perenne were investigated. The highest protoplast yield of 10×10⁶ g⁻¹FW was obtained when cell suspensions were used as the tissue source, with enzyme combination 'A' (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. Development of microcolonies was only achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. All the shoots regenerated from the protoplast-derived calli were albino shoots. The highest protoplast yield (7×10⁶ g⁻¹FW) of L. corniculatus was achieved from cotyledons also with enzyme combination 'A' (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. The highest plating efficiency for L. corniculatus of 1.57 % was achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. The highest frequency of shoot regeneration (46%) was achieved when calli were plated on LS medium with NAA (0.1 mg/L) and BA (0.1 mg/L). Protoplast fusion between L. perenne and L. corniculatus was performed using the asymmetric somatic hybridisation technique using PEG as the fusogen. L. perenne protoplasts were treated with 0.1 mM IOA for 15 min and L. corniculatus protoplasts were treated with UV at 0.15 J/cm² for 10 min. Various parameters affecting the fusion percentage were investigated. Successful fusions were obtained when the fusions were conducted on a plastic surface with 35% PEG (3350 MW) for 25 min duration, followed by 100 mM calcium chloride treatment for 25 min. A total of 14 putative fusion colonies were recovered. Shoots were regenerated from 8 fusion colonies. Unexpectedly, the regenerated putative hybrid plants resembled L. corniculatus plants. The flow cytometric profile of the putative somatic hybrids resembled that of L. corniculatus. Molecular analysis using SD-AFLP, SCARs and Lolium specific chloroplast microsatellite markers suggest that the putative somatic hybrids could be L. corniculatus escapes from the asymmetric protoplast fusion process. This thesis details a novel Whole Genome Amplification technique for plants using Strand Displacement Amplification technique.
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Leeks, C. R. F. "Determining seed vigour in selected Brassica species." Lincoln University, 2006. http://hdl.handle.net/10182/1274.
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Variables for the accelerated ageing (AA) test, methods for reducing fungal contamination during the AA test, using the conductivity test as a vigour test, the effect of seed size on seed vigour and the relationship between laboratory test results and field perfonnance in selected Brassica spp were investigated. In the first experiment, three seed lots of turnip rape hybrid (B. rapa x campestris), turnip (B. campestris) and forage rape (B. napus); and seven seed lots of Asian rape (B. napus), six seed lots of Asian kale (B. oleraceae var. alboglabra L.) and five seed lots of choisum (B. rapa var. pekinensis) with germinations above 90% were aged at two different temperatures (41 and 42°C ± 0.3°C) and three ageing times (24, 48 and 72 ± 15 minutes). The second experiment was divided into three sections. In the first, the same seed lots and species were aged at one temperature (41°C) and time (72 h), but either 40 ml of saturated salts; KCl (83%RH), NaCl (76%RH), NaBr (55%RH); or distilled water (96%RH) were used as the ageing solutions. In the second, one turnip rape hyprid seed lot was aged at three temperatures (41, 42 and 45°C) and two times (72 and 96h), again using the three saturated salts and distilled water as ageing solutions. In the third, three turnip rape hybrid seed lots and three Asian kale seed lots were surface sterilised (1 % sodium hypochlorite) prior to ageing at one temperature (41°C) and time (72 h). In the third experiment, the same species and seed lots used in experiment one at their original seed moisture content (SMC) were tested for conductivity after soaking in deionised water for 4, 8, 12, 16, 20 and 24 h. They were then re-tested after the SMC had been adjusted to 8.5%. In the fourth experiment, three seed lots of forage rape and three seed lots of Asian kale were graded into three seed size categories; large (retained on a 2.0 mm screen), medium (retained on a 1.7 mm screen) and small (passed through a 1.7 mm screen). Graded seeds were then tested for standard germination, AA (41°C/48 h) and conductivity (measured at 16 and 24 h). In the final experiment, the relationships between laboratory tests for the six species (each consisting of three seed lots), field emergence from three sowings, and cold room emergence were evaluated. Both time and temperature influenced post-AA germination. Increasing the ageing period from 48 to 72 hours at 41°C, and 24 to 48 hours at 42°C resulted in decreased mean germination percentage for all species but not always clear separation of seed lots. While there were sometimes few differences between ageing at 41°C and 42°C, the former is preferred because it is already the temperature used for other species. For Asian rape, choisum and turnip, the previously recommended testing conditions of 41°C/72 h provided good seed lot separation, but for Asian kale and turnip rape hybrid, AA testing at 41°C/48 h provided better results. Seed moisture content after ageing ranged from 29-37% depending on species. Fungal growth on seeds during the ageing period appeared to reduce post-ageing germination in some seed lots . Substituting saturated salts for distilled water did not stress seed lots in the AA test, due to the lowered RH%, the exception being seed lots 1210 and 1296. For forage and Asian species, seed lot germination mostly remained above 90% when aged for 72 h at lowered RH%. Increasing the ageing duration from 72 to 96 hours resulted in some decreases in post-AA germination but no clear separation of seed lots. Surface sterilising the seeds prior to the AA test resulted in a lower incidence of contaminant fungi which was associated with a lower percentage of abnormal seedlings. The conductivity test was mostly able to identify vigour differences among forage and Asian vegetable brassica seed lots. Differences in conductivity readings were observed among seed lots in all species. Increasing the period of imbibition resulted in increased conductivity from most seed lots but radicle emergence occurred after 16-20 h of imbibition. Variation was observed in the time to reach 95% maximum of the imbibition curve for most species. Conductivity readings at 16 h would avoid possible influences of radicle emergence on results. Adjusting the SMC to 8.5% resulted in reduced variation in conductivity among replicates of seed lots, due to a reduction in imbibition damage. Seed size had a significant effect on both post-AA germination and conductivity results. In forage rape, large size seeds had higher post-AA germination cf. medium cf. small size seeds. In Asian kale, large size seeds had higher post-AA germination compared with small size seeds. For both forage rape and Asian kale, large size seeds had lower conductivity readings cf. small size seeds. The correlation analyses demonstrated significant relationships between AA testing and field emergence parameters (percentage emergence, emergence index and emergence rate). Significant relationships were also observed between conductivity testing and these field emergence parameters. Based on the correlation analysis, AA testing at 41°C/48 hand/or 42°C/48 h could be recommended to be used as an AA test for turnip and Asian rape; and 41°C/48 hand/or 41°C/72 h for Asian kale and choisum. Based on the correlation analysis, conductivity testing at 16 h can be used to predict the field emergence potential of forage and Asian vegetable seed lots. Vigour tests were consistently able to provide better indicators of field perfonnance than the standard germination test, although these relationships did vary with the different field sowings.
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Moot, Derrick J. "Harvest index variability within and between field pea (Pisum sativum L.) crops." Lincoln University, 1993. http://hdl.handle.net/10182/1285.
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The association between individual plant performance and seed yield variability within and between field pea crops was investigated. In 1988/89 six F8 genotypes with morphologically distinct characteristics were selected from a yield evaluation trial. Analysis of the individual plant performance within these crops indicated an association between low seed yields and the location and dispersion of plant harvest index (PHI) and plant weight (PWT) distributions. The analyses also showed there was a strong linear relationship between the seed weight (SWT) and PWT of the individual plants within each crop, and that the smallest plants tended to have the lowest PHI values. A series of 20 simulations was used to formalize the relationships between SWT, PWT and PHI values within a crop into a principal axis model (PAM). The PAM was based on a principal axis which represented the linear relationship between SWT and PWT, and an ellipse which represented the scatter of data points around this line. When the principal axis passed through the origin, the PHI of a plant was independent of its PWT and the mean PHI was equal to the gradient of the axis. However, when the principal axis had a negative intercept then the PHI was dependent on PWT and a MPW was calculated. In 1989/90 four genotypes were sown at five plant populations, ranging from 9 to 400 plants m⁻². Significant seed and biological yield differences were detected among genotypes at 225 and 400 plants m⁻². The plasticity of yield components was highlighted, with significant genotype by environment interactions detected for each yield component. No relationship was found between results for yield components from spaced plants and those found at higher plant populations. The two highest yielding genotypes (CLU and SLU) showed either greater stability or higher genotypic means for PHI than genotypes CVN and SVU. Despite significant skewness and kurtosis in the SWT, PWT, and PHI distributions from the crops in this experiment, the assumptions of the PAM held. The lower seed yield and increased variability in PHI values for genotype CVN were explained by its higher MPW and the positioning of the ellipse closer to the PWT axis intercept than in other genotypes. For genotype SVU, the lower seed yield and mean PHI values were explained by a lower slope for the principal axis. Both low yielding genotypes were originally classified as having vigorous seedling growth and this characteristic may be detrimental to crop yields. A method for selection of field pea genotypes based on the PAM is proposed. This method enables the identification of weak competitors as single plants, which may have an advantage over vigorous plants when grown in a crop situation.
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Sanoamuang, Niwat. "Epidemiological aspects of MBC resistance in Monilinia fructicola (Wint.) Honey and mechanisms of resistance." Lincoln University, 1992. http://hdl.handle.net/10182/1362.
Full textAbstract:
Isolates of Monilinia fructicola (Wint.) Honey obtained from stone fruit orchards in Hawkes Bay, North Island and from Californian fruit exported to New Zealand, were tested for resistance to methyl benzimidazole carbamate (MBC). Resistant isolates from the North Island had EC₅₀ values of >30,000, and most isolates from the imported fruit had of values approximately 1.5 mg a.i./l carbendazim. Sensitive isolates failed to grow on 1 mg a.i./l carbendazim. A detached peach shoot system was used in controlled conditions for estimation of values for incubation period, latent period and rate of spore production on flowers (cv Glohaven). The same variables and the rate of colonisation of host tissue were measured on fruit (cv Fantasia) in controlled conditions. An inoculum density of 1x10⁴ spore/flower or fruit greatly increased fitness in vivo compared to an inoculum density of 1x10² spore/flower (fruit). Isolates varied considerably, but there was no consistent relationship between the degrees of resistance and fitness. This was in contrast to earlier studies with dicarboximide resistant strains of M. fructicola. The survival in the field of 10 isolates resistant or sensitive to MBC or dicarboximide fungicides on twig cankers and mummified fruit was compared. The ability to produce conidia on twig cankers inoculated in late spring 1989 was maintained by all sensitive and MBC resistant isolates for at least 1 year. The production of conidia on mummified fruit inoculated in February 1990 decreased after 2-3 months in the field but some conidia were still produced on all fruit in the following spring. Dicarboximide resistant isolates produced less conidia than either the MBC resistant and the sensitive isolates. The pathogenicity and fitness of all isolates were similar to the original values after survival for 1 year. A technique was developed to produce apothecia reliably from inoculated peach (cv Black Boy) and nectarine (cv Fantasia) fruit in controlled conditions in the laboratory. The fruit were inoculated with resistant or sensitive isolates, or combinations, and were incubated for 8 weeks at 25°C (±1°C) with 12 hours photoperiod of fluorescent light (Sylvania 2x65 W, daylight) to produce mummified fruit. The fruit were then buried in moist autoclaved peat moss for 10 weeks at 25°C (±1°C) in the dark to form stromata. These fruit were then hydrated with running tap-water (total hardness (CaCO₃) = 47 g/m³ and conductivity at 20°C = 12.7 mS/m) for 72 hours. The hydrated mummified fruit were placed in moist peat moss and were incubated for 13-14 weeks at 8°C (±0.5°C) in the dark. At the end of this period, stipe initials were visible. Differentiation of stipe initials into mature apothecia occurred within 15-20 days after transfer to 12°C (±2 °C) with a 12 hour photoperiod of fluorescent and incandescent light. All isolates produced apothecia when treated in this way. A technique for isolation of ascospore sets in linear arrangement was developed for tetrad analysis of the inheritance of resistance. At least 3 hours of fluorescent and incandescent light at 12°C (±2°C) was essential to allow ascospore ejection from individual asci taken from apothecia previously maintained in a 12 hour photoperiod at 12°C (±1°C). A water film on the surface of water agar was necessary to hold a set of ejected ascospores in linear sequence. Single ascospores were obtained in sequence with the aid of a micromanipulator. Genetic analysis of MBC resistant isolates was carried out on ascospores derived from apothecia produced in the laboratory. Analysis of ascospore sets in linear arrangement and ascospore populations indicated that resistance to >30,000 mg a.i./l carbendazim (high-resistant) is governed by a single major gene and is affected by gene conversion mechanisms. Crossing over was frequent, suggesting that recombination of resistance with other characters, such as pathogenicity and fitness, may occur readily. The segregation ratio (1:1) from most resistant isolates revealed that heterokaryons containing both resistant and sensitive alleles were common in resistant populations and that resistance is dominant. Allozyme analysis of ascospore progeny through electrophoresis revealed a narrow genetic base of M. fructicola in New Zealand. The technique for reliable apothecial production in controlled conditions developed in this study provided an important step for the determination of the biology of M. fructicola strains resistant to MBC fungicides, and the complexity of its life cycle. Genetic heterogeneity in field populations can be conserved in one isolate through heterokaryosis, thus providing for adaptability of the pathogen to the changing environmental conditions. Knowledge on genetic variability, overwintering ability, pathogenicity and fitness factors may be useful for future management strategies of stone fruit brown rot. Special emphasis should be made in particular to prevent primary infection on blossoms, which would delay the establishment of recombinant strains of M. fructicola and the onset of brown rot epidemics.
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Li, H. "Identification and characterization of quantitative trait loci (QTLs) associated with waterlogging tolerance in barley (Hordeum vulgare L.)." Thesis, 2007. https://eprints.utas.edu.au/6091/1/Li_whole_thesis.pdf.
Full textAbstract:
Waterlogging is a major environmental constraint severely limiting crop production both in Australia and worldwide. In Australia, most barley cultivars are waterlogging sensitive and increasing their tolerance is an important breeding objective in regions of high rainfall. However, little genetic research and progress has been made on improving barley for waterlogging tolerance, mainly because it is a complex abiotic stress that is affected by many factors such as temperature, plant development stage, nutrient, soil type and topography. The aims of this PhD project were to: (i) investigate the genetic behavior and quantitative inheritance of waterlogging tolerance in barley; (ii) identify and validate quantitative trait loci (QTL) for waterlogging tolerance in barley.
A quantitative genetic analysis of waterlogging was conducted with a 6 X 6 half diallel experiment between three Chinese tolerant cultivars and three susceptible Australian and Japanese cultivars. The six parents and 15 F\(_2\) from each cross were seeded into two steel tanks (replications), flooded for 10 days and measured for mean yellow leaf percentage. This trait was chosen as other studies have found it to be correlated with waterlogging tolerance. The mean leaf chlorosis of all the F\(_2\)s was similar to that of their mid-parent values. Leaf chlorosis percentages followed an additive model with no significant dominance effect and possessed a high heritability. This experiment demonstrated that selecting in early generations for this trait would be effective.
For the purpose of identification of quantitative trait loci controlling waterlogging tolerance in barley, two linkage maps were constructed, based on doubled haploid populations from crosses between TX9425 (waterlogging tolerant) x Franklin (sensitive), and Yerong (tolerant) x Franklin. The TX9425/Franklin linkage map comprised 412 Diversity Array (DArT) markers, 27 SSR and 81 AFLP markers organized into 8 linkage groups and covering 956 cM. The Yerong/Franklin linkage map was based on 496 DArT and 22 SSR markers assigned to 9 linkage groups and covered 1084.5 cM. The robustness of the DArT markers was confirmed when linkage maps were generated from two sub-sets of progenies in the Y erong/Franklin population, which were genotyped in different batches (arrays). The resuJts indicated that the 496 markers were assigned to exactly the same seven different chromosomes in each of the two experiments. Only minor changes in marker order within chromosomes were found. A relatively large proportion of the molecular markers showed distorted segregation and the possible causes of this are discussed. In order to synthesize the genetic information contained in the two linkage maps produced in this project together with two other maps using DArT markers, a consensus map was constructed which could serve for barley molecular breeding in the future, and as a basis for studies of genome organization and evolution. For example, many more markers showed segregation distortion than expected. Out of the 2975 markers used across all four populations 21.1 %, 10.9%, and 7 .9% exhibited segregation distortion at 5%, 1 %, and 0.5% probability threshold respectively. DArT markers were not more likely to show segregation distortion than other marker types. Of the 63 5 markers showing aberrant segregation in the four populations, 459 markers were located in 16 putative segregation distortion regions (SDR). The SDRs were identified on all seven barley chromosomes, but they were unevenly distributed over the seven chromosomes and their size varied from 4 to 46 cM. Ten of the SDRs were found in at least two populations and several at a consistent map location over the four populations. Further studies are needed to determine the molecular basis of segregation distortion.
In order to detect QTL for waterlogging tolerance in barley, the two mapping populations were tested for germination (six replicates of fifty seeds each, submerged in 50 ml of water for six days, then moved to incubators for germination), leaf chlorosis, biomass reduction and survival (four replicates (tanks), five plants from each DH and parental lines sown in pots, placed in tanks, three of which were flooded and one used as a control). QTL analysis found a total of 6 distinct QTLs for the four traits in the Franklin/TX9425 population and 6 QTLs in the Franklin/Y erong population. QTL controlling leaf chlorosis were quite similar in their location between the two populations, the most important QTL found being in the same region of chromosome 3H in each population. One QTL controlling plant survival rate was located on chromosome 2H in both populations. A QTL for biomass reduction was identified in each population to chromosome 4H. However, it may not be the same QTL because they mapped to slightly different regions of that chromosome in each population. A QTL for seed germination was located on chromosome lH in the Franklin/TX9425 population. However, this QTL was different from the QTL controlling leaf chlorosis, which mapped to a different region of the same chromosome. In this study strong QTLs were identified, which could be cross-validated in different mapping population for traits correlated with waterlogging tolerance in barley. Thus there is good scope for using marker assisted selection in breeding for waterlogging tolerance in barley. However, these QTL will need to be further validated through field experiments and yield measurements under waterlogging conditions.
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Hamilton, MG. "The genetic improvement of Eucalyptus globulus and E. nitens for solidwood production." Thesis, 2007. https://eprints.utas.edu.au/5963/1/PhD_Final_Matthew_Hamilton_eprints.pdf.
Full textAbstract:
Eucalyptus globulus and E. nitens are among the most important plantation
eucalypts in temperate regions of the world. Although pulpwood production is the
principal focus of most forest growers, there is increasing interest in producing
sawn-timber from E. globulus and E. nitens plantations. This thesis investigated
breeding as a means of improving the solidwood characteristics of E. globulus and
E. nitens.
Data relating to genetic variation in E. nitens was collated from the literature.
However, only a small number of independent parameter estimates were available
for solidwood traits. This was similarly the case in E. globulus.
In E. globulus, the lower stem, which represents a high proportion of total stem
volume, was found to have the least favourable wood properties for kraft pulpwood
and most solidwood applications. Subrace by height category interactions in bark
thickness, basic density, decay and gross shrinkage indicated that differences
among subraces were dependent on height in these traits.
The utility of measuring shrinkage in small wood samples (e.g.12-mm cores) as a
cheap and non-destructive means of selecting against drying defects in sawn
products was investigated. A number of methods of assessing shrinkage in
samples were examined. Volume- and calliper-assessment of gross shrinkage were
deemed the most promising assessment techniques based on genetic and practical
considerations.
A strong genetic correlation between collapse and gross shrinkage in E. nitens wood
samples indicated that most genetic variation in gross shrinkage was explained by
collapse rather than normal shrinkage even when cores were dried at low
temperature. In E. globulus, strong genetic correlations in gross shrinkage between
drying treatments indicated that genotype by drying treatment interaction was of
limited consequence over a wide range of drying conditions.
Relationships between pulpwood selection traits and sample shrinkage traits were
investigated. Genetic correlations between basic density and gross shrinkage were
generally negative (i.e. favourable) in both species. In contrast, the strength and
direction of genetic correlations between growth and gross shrinkage varied widely between and within studies. In E. nitens, the genetic correlation between predicted
cellulose content and gross shrinkage was found to be positive (i.e. adverse) but not
significantly different to zero.
Although significant genetic variation was detected in shrinkage traits, the efficacy of
reducing drying-degrade in sawn boards by selecting trees according to sample
shrinkage remains unclear. A small-scale E. globulus sawmilling study identified
significant genetic variation in some board drying defects but did not find strong
correlations between sample gross shrinkage and these defects. Furthermore, a
very low intersite genetic correlation in sample gross shrinkage was observed in an
E. nitens study.
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McGowen, MH. "Genetic control of reproductive traits in Eucalyptus globulus." Thesis, 2007. https://eprints.utas.edu.au/5707/.
Full text
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Mweshi, Mukanga. "Genetic improvement of Zambian maize (Zea mays L.) populations for resistance to ear rots and a survey of associated mycotoxins." Thesis, 2009. http://hdl.handle.net/10413/519.
Full textAbstract:
Maize ear rots are among the most important impediments to increased maize production in Africa. Besides yield loss, they produce mycotoxins in their host whose contamination has been linked to several human and animal mycoses. The main objectives of the studies reported on in this thesis were (i) to investigate farmer perceptions of maize ear rot disease and prospects for breeding for host plant resistance in Zambia; and (ii) to establish the levels of incidence and extent of maize ear rot infection as well as the level of mycotoxins in the maize crops of smallholder farms in central and southern Zambia; (iii) to appraise the field inoculation techniques and assess them for their suitability for the Zambian environmental conditions, (iv) to determine the combining ability of Zambian maize populations for resistance to ear rot and investigate the genetic basis of this resistance; and (v) to investigate both direct and indirect responses to full-sib selection for ear rot resistance in Zambian maize populations. A participatory rural appraisal (PRA) was conducted in four communities, involving a total of 90 farmers. Participatory methods were used, such as focused group discussions, group interviews, participant scoring and ranking. Farmers ranked and scored the various constraints affecting their maize production in general and the maize ear rots in particular. Ear rots were ranked as the third most important biotic stress and it was evident that although farmers were aware of the disease, they were not aware of mycotoxins. This was reflected in the way they disposed of rotten maize: either by feeding livestock or eating it in periods of hunger. The survey of ear rots and mycotoxins was carried out in the Southern and Central Provinces of Zambia. A total of 114 farms were covered in the survey: maize samples were collected and both ear rot fungi and mycotoxins were isolated. Fusarium and Stenocarpella were the most frequently isolated fungi from smallholder farms. The levels of fumonisins on these farms ranged from 0.05 to 192 ppm, while those of aflatoxins were between 1.5 and 10.6 ppb. In 50% of the farmsteads surveyed, the mycotoxins, i.e. fumonisins and aflatoxins, exceeded the recommended FAO/WHO 1limits of 2 ppm and 2 ppb, respectively. Five field inoculation techniques namely, colonised toothpick, leaf whorl placement, ear top placement, spore suspension spray, and silk channel injection, were evaluated over three seasons in a series of experiments. It was found that the leaf whorl placement of inoculums, followed by colonized toothpick method, gave a constant ranking of genotypes across locations and years compared to the other three methods. In addition, the use of a mixture of ear rots as inoculum was as effective as its principal single species constituents. In the population diallel analysis, five broad-based maize populations were crossed in a diallel and evaluated under artificial ear rot inoculation using an inoculum mixture of three ear rot fungi, Aspergillus flavus, Fusarium verticilloides and Stenocarpella maydis at four locations in Zambia. The purpose was to estimate general (GCA) and specific combining ability (SCA) and investigate genotype x environment interaction. GCA effects were found not to be significant for disease severity but were significant for grain yield across environments. Populations with a strong GCA effect for disease severity across sites included PRA783244c3, Pop25, MMV600, and ZUCASRc2. Across sites, the F1 combinations, MMV600 x Pop25, ZUCASRc2 X Pop25, and Pop25 x PRA783244c2 had strong SCA effects for root lodging, ear drooping, husk cover and ear insect damage. In a related diallel analysis of 10 full-sib families derived from these populations, it was observed that resistant x susceptible families and their reciprocal crosses performed better than their resistant parents, suggesting an over dominant expression of resistance. Both maternal and non maternal effects were observed to be influencing resistance to ear rots. There was a preponderance influence of non-additive gene action. A response to full-sib recurrent selection was conducted in four locations in Central Zambia. Out of the 343 families created in 2005/6 season, 10% were selected from each population and recombined to create five new populations. These, with the original populations, were evaluated in four sites during the 2007/8 season. There was a net reduction in ear rot incidence and rot severity in the new synthetic population. Pop10 had the largest reduction in disease severity. The predicted gain per cycle was -4.1% and realized gain was -2.5% for disease incidence, and 0.19% and 19.4% for grain yield. Genetic variability was maintained though with low heritability estimates. Negative but at times strong association between grain yield and ear rot disease severity was detected suggesting that in general selecting for ear rot resistance would enhance grain yield in the five populations. Overall the importance of the ear rots and mycotoxins in compromising yield and health of the communities in Zambia, respectively, were confirmed and support the call to improve maize varieties for resistance to ear rots. The results indicate that the five populations could be enhanced for ear rot resistance through population improvement procedures such reciprocal recurrent selection that exploit both additive and non-additive variation. Selection might be compromised by the large genotype x environment interaction effects, and large reciprocal effects and their interaction with the environments. To enhance repeatability genotypes should be artificially inoculated, by placing the inoculum in the leaf whorl followed by colonized toothpick inoculation, and screened in many environments to identify genotypes with stable resistance to ear rots.Thesis (Ph.D) - University of KwaZulu-Natal, Pietermaritzburg, 2009.
Books on the topic "Plant improvement (selection, breeding and genetic engineering)"
1
Stadler Genetics Symposium (19th 1989 University of Missouri--Columbia). Gene manipulation in plant improvement II: 19th Stadler Genetics Symposium. New York: Plenum Press, 1990.
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2
Kriz, Alan Lawrence, and B. A. Larkins. Molecular Genetic Approaches to Maize Improvement. Edited by Nagata T. (Toshiyuki), Löorz Horst, Widholm Jack M, and SpringerLink (Online service). Berlin, Heidelberg: Springer Berlin Heidelberg, 2009.
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3
Bajaj, Y. P. S., 1936-, ed. Haploids in crop improvement I. Berlin: Springer-Verlag, 1990.
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4
R, Khanna K., ed. Biochemical aspects of crop improvement. Boca Raton: CRC Press, 1991.
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5
International Symposium on the Use of Induced Mutations and Molecular Techniques for Crop Improvement (1995 Vienna, Austria). Induced mutations and molecular techniques for crop improvement: Proceedings of an International Symposium on the Use of Induced Mutations and Molecular Techniques for Crop Improvement. Vienna: International Atomic Energy Agency, 1995.
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6
International Symposium and Workshop on Gene Manipulation for Plant Improvement in Developing Countries (1987 Kuala Lumpur, Malaysia). Plant breeding and genetic engineering: Proceedings of the International Symposium and Workshop on Gene Manipulation for Plant Improvement in Developing Countries held at Kuala Lumpur, Malaysia, 30 November-3 December 1987. Bangi, Selangor Darul Ehsan, Malaysia: Society for the Advancement of Breeding Researches in Asia and Oceania, 1988.
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7
E, Sadava David, and Chrispeels Maarten J. 1938-, eds. Plants, genes, and crop biotechnology. 2nd ed. Boston: Jones and Bartlett Publisher, 2003.
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8
International Symposium on Nuclear Techniques and In Vitro Culture for Plant Improvement (1985 Vienna, Austria). Nuclear techniques and in vitro culture for plant improvement: Proceedings of an International Symposium on Nuclear Techniques and In Vitro Culture for Plant Improvement : jointly organized by the International Atomic Energy Agency and the Food and Agriculture Organisation of the United Nations and held in Vienna, 19-23 August 1985. Vienna: IAEA, 1986.
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9
Crop breeding: Bioinformatics and preparing for climate change. Oakville, ON: Apple Academic Press, 2015.
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10
Conference on Tailoring Genes for Crop Improvement (1986 University of California, Davis). Tailoring genes for crop improvement: An agricultural perspective. New York: Plenum Press, 1987.
Find full textBook chapters on the topic "Plant improvement (selection, breeding and genetic engineering)"
1
Crossa, José, J. Jesús Cerón-Rojas, Johannes W. R. Martini, Giovanny Covarrubias-Pazaran, Gregorio Alvarado, Fernando H. Toledo, and Velu Govindan. "Theory and Practice of Phenotypic and Genomic Selection Indices." In Wheat Improvement, 593–616. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90673-3_32.
Full textAbstract:
AbstractThe plant net genetic merit is a linear combination of trait breeding values weighted by its respective economic weights whereas a linear selection index (LSI) is a linear combination of phenotypic or genomic estimated breeding values (GEBV) which is used to predict the net genetic merit of candidates for selection. Because economic values are difficult to assign, some authors developed economic weight-free LSI. The economic weights LSI are associated with linear regression theory, while the economic weight-free LSI is associated with canonical correlation theory. Both LSI can be unconstrained or constrained. Constrained LSI imposes restrictions on the expected genetic gain per trait to make some traits change their mean values based on a predetermined level, while the rest of the traits change their values without restriction. This work is geared towards plant breeders and researchers interested in LSI theory and practice in the context of wheat breeding. We provide the phenotypic and genomic unconstrained and constrained LSI, which together cover the theoretical and practical cornerstone of the single-stage LSI theory in plant breeding. Our main goal is to offer researchers a starting point for understanding the core tenets of LSI theory in plant selection.
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Crespo-Herrera, Leonardo A., José Crossa, Mateo Vargas, and Hans-Joachim Braun. "Defining Target Wheat Breeding Environments." In Wheat Improvement, 31–45. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90673-3_3.
Full textAbstract:
AbstractThe main objective of a plant breeding program is to deliver superior germplasm for farmers in a defined set of environments, or a target population of environments (TPE). Historically, CIMMYT has characterized the environments in which the developed germplasm will be grown. The main factors that determine when and where a wheat variety can be grown are flowering time, water availability and the incidence of pests and diseases. A TPE consists of many (population) environments and future years or seasons, that share common variation in the farmers’ fields, it can also be seen as a variable group of future production environments. TPEs can be characterized by climatic, soil and hydrological features, as well as socioeconomic aspects. Whereas the selection environments (SE) are the environments where the breeder does the selection of the lines. The SE are identified for predicting the performance in the TPE, but the SE may not belong to the TPE. The utilization of advanced statistical methods allows the identification of GEI to obtain higher precision when estimating the genetic effects. Multi-environmental testing (MET) is a fundamental strategy for CIMMYT to develop stable high grain yielding germplasm in countries with developing economies. An adequate MET strategy allows the evaluation of germplasm in stress hotspots and the identification of representative and correlated sites; thus, breeders can make better and targeted decisions in terms of crossing, selection and logistic operations.
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Maccaferri, Marco, Martina Bruschi, and Roberto Tuberosa. "Sequence-Based Marker Assisted Selection in Wheat." In Wheat Improvement, 513–38. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90673-3_28.
Full textAbstract:
AbstractWheat improvement has traditionally been conducted by relying on artificial crossing of suitable parental lines followed by selection of the best genetic combinations. At the same time wheat genetic resources have been characterized and exploited with the aim of continuously improving target traits. Over this solid framework, innovations from emerging research disciplines have been progressively added over time: cytogenetics, quantitative genetics, chromosome engineering, mutagenesis, molecular biology and, most recently, comparative, structural, and functional genomics with all the related -omics platforms. Nowadays, the integration of these disciplines coupled with their spectacular technical advances made possible by the sequencing of the entire wheat genome, has ushered us in a new breeding paradigm on how to best leverage the functional variability of genetic stocks and germplasm collections. Molecular techniques first impacted wheat genetics and breeding in the 1980s with the development of restriction fragment length polymorphism (RFLP)-based approaches. Since then, steady progress in sequence-based, marker-assisted selection now allows for an unprecedently accurate ‘breeding by design’ of wheat, progressing further up to the pangenome-based level. This chapter provides an overview of the technologies of the ‘circular genomics era’ which allow breeders to better characterize and more effectively leverage the huge and largely untapped natural variability present in the Triticeae gene pool, particularly at the tetraploid level, and its closest diploid and polyploid ancestors and relatives.
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Trethowan, Richard M. "Abiotic Stresses." In Wheat Improvement, 159–75. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90673-3_10.
Full textAbstract:
AbstractAbiotic stresses, such as drought and high temperature, significantly limit wheat yield globally and the intensity and frequency of these stresses are projected to increase in most wheat growing areas. Wheat breeders have incrementally improved the tolerance of cultivars to these stresses through empirical selection in the environment, however new phenotyping and genetic technologies and strategies can significantly improve rates of genetic gain. The integration of new tools and knowledge in the plant breeding process, including better breeding targets, improved choice of genetic diversity, more efficient phenotyping methods and strategy and optimized integration of genetic technologies in the context of several commonly used wheat breeding strategies is discussed. New knowledge and tools that improve the efficiency and speed of wheat improvement can be integrated within the scaffold of most wheat breeding strategies without significant increase in cost.
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Yamori, Wataru. "Strategies for Engineering Photosynthesis for Enhanced Plant Biomass Production." In Rice Improvement, 31–58. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66530-2_2.
Full textAbstract:
AbstractCrop productivity would have to increase by 60–110% compared with the 2005 level by 2050 to meet both the food and energy demands of the growing population. Although more than 90% of crop biomass is derived from photosynthetic products, photosynthetic improvements have not yet been addressed by breeding. Thus, it has been considered that enhancing photosynthetic capacity is considered a promising approach for increasing crop yield. Now, we need to identify the specific targets that would improve leaf photosynthesis to realize a new Green Revolution. This chapter summarizes the various genetic engineering approaches that can be used to enhance photosynthetic capacity and crop productivity. The targets considered for the possible candidates include Rubisco, Rubisco activase, enzymes of the Calvin–Benson cycle, and CO2 transport, as well as photosynthetic electron transport. Finally, it describes the importance of considering ways to improve photosynthesis not under the stable environmental conditions already examined in many studies with the aim of improving photosynthetic capacity, but under natural conditions in which various environmental factors, and especially irradiation, continually fluctuate.
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Tony Fischer, R. A. "History of Wheat Breeding: A Personal View." In Wheat Improvement, 17–30. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90673-3_2.
Full textAbstract:
AbstractFor more than a century, breeding has delivered huge benefits as a major driver of increased wheat productivity and of stability in the face of inevitable disease threats. Thus, the real cost of this staple grain has been reduced for billions of consumers. Steady breeding progress has been seen across many important traits of wheat, currently for potential yield averaging about 0.6% p.a. This yield progress continues to rely of extensive multilocational yield testing but has, however, become more difficult, even as new breeding techniques have improved efficiency. Breeding will continue to evolve as new approaches, being proposed with increasing frequency, are tested and found useful or not. High throughput phenotyping (HTPP), applying modern crop physiology, and molecular markers and genomic selection (GS) are in this phase right now. Such new techniques, along with pre-breeding for new traits, will likely play a larger role in this future improvement of wheat. New tools will also include genetic engineering (GE), as society’s need for its benefits become more urgent. The steady privatization of breeding seems unlikely to cease in the developed world but will continue to struggle elsewhere. It would seem wise, however, that a significant portion of the world’s pre-breeding research remains in the public sector, while maintaining close and equitable contact with those delivering new varieties.
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Langridge, Peter. "Micronutrient Toxicity and Deficiency." In Wheat Improvement, 433–49. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90673-3_24.
Full textAbstract:
AbstractMicronutrients are essential for plant growth although required in only very small amounts. There are eight micronutrients needed for healthy growth of wheat: chlorine, iron, boron, manganese, zinc, copper, nickel and molybdenum. Several factors will influence the availability of micronutrients, including levels in the soil, and mobility or availability. Zinc deficiency is the most significant problem globally followed by boron, molybdenum, copper, manganese and iron. Deficiency is usually addressed through application of nutrients to seeds, or through foliar spays when symptoms develop. There is considerable genetic variation in the efficiency of micronutrient uptake in wheat, but this is not a major selection target for breeding programs given the agronomic solutions. However, for some micronutrients, the concentrations in the soil can be very high and result in toxicity. Of the micronutrients, the narrowest range between deficiency and toxicity is for boron and toxicity is a significant problem in some regions. Although not a micronutrient, aluminium toxicity is also a major factor limiting yield in many areas, usually associated with a low soil pH. Agronomic solutions for boron and aluminium toxicity are difficult and expensive. Consequently, genetic approaches have dominated the strategies for addressing toxicity and good sources of tolerance are available.
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Kumar, Vikash, Anjali Chauhan, Avinash Kumar Shinde, Ramesh L. Kunkerkar, Deepak Sharma, and Bikram Kishore Das. "Mutation breeding in rice for sustainable crop production and food security in India." In Mutation breeding, genetic diversity and crop adaptation to climate change, 83–99. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0009.
Full textAbstract:
Abstract With the inevitable risk posed by global climate change affecting crop yield and the ever-increasing demands of agricultural produce, crop improvement techniques need to be more precise in developing smart crop varieties. The rice crop, a staple food for the majority of the world population, has a significant role to play in alleviating the global hunger problem. With the world population burgeoning at an unprecedented rate, limited fertile land resources, climate change, emerging new races of pests and diseases and consumer preferences for quality attributes, it is imperative to increase crop diversity, and this requires better selection efficiency addressing the challenges of future rice production. Mutation breeding is a fundamental and very successful tool helping to increase crop diversity and allowing plant breeders to exercise their skill in developing desirable crop varieties. The induction of mutations has been used to enhance yield, improve nutritional quality and widen the adaptability of the world's most important crops such as wheat, rice, pulses, millets and oilseeds. India is considered to be one of the primary centres of origin of crop species with the concomitant very high genetic diversity in traditional landraces for different agronomic traits of economic importance. Plant architecture, such as plant height, branching habit (tiller number), leaf shape and patterns, floral and grain traits and quality traits such as aroma, amylose content and cooking quality are of tremendous importance for rice improvement programmes. Traditional landraces of rice have premium grain quality, fetching a premium price, but their cultivation is being marginalized due to their tall stature, proneness to lodging, late maturity and poor yield. Mutation breeding technology has been successfully implemented in rice improvement programmes, which have resulted in the improvement of aromatic rice varieties, such as 'Pusa Basmati 1', 'Dubraj and Jawaphool'. Two high-yielding mutant rice varieties, TCDM-1 ('Trombay Chhattisgarh Dubraj Mutant-1') and TKR Kolam ('Trombay Karjat Rice Kolam'), have been released for cultivation in Chhattisgarh and the Konkan region of Maharashtra. Both these varieties possess dwarf plant stature (110 cm), medium maturity (130 days), premium grain quality and resistance to major pests and diseases. Improvement of other traditional rice varieties is underway which will bring these varieties back into cultivation and help in improving the tribal and marginal farmers' economy.
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Sofkova-Bobcheva, Svetla, Ivelin Pantchev, Ivan Kiryakov, Petar Chavdarov, Yordan Muhovski, Fatma Sarsu, and Nasya Tomlekova. "Induced mutagenesis for improvement of bean (Phaseolus vulgaris L.) production in Bulgaria." In Mutation breeding, genetic diversity and crop adaptation to climate change, 178–93. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0018.
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Abstract Although historically a surplus food producer, Bulgarian agriculture has faced a downturn in recent decades. Local legume cultivars have lost favour with farmers and the canning industry, due to their low productivity in comparison with imported ones. Diseases and abiotic stresses are the most important factors limiting the production of edible legumes, costing farmers hundreds of euros in lost revenue each year. The overall objective of our ongoing bean mutation breeding programme was to enrich the gene pool of Phaseolus vulgaris L. and to develop genotypes resistant to Xanthomonas axonopodis pv. phaseoli (Smith) (Xap) and Pseudomonas savastanoi pv. phaseolicola (Burkh.) (Psp) using EMS. An elite line and common cultivar (an heirloom and a snap bean type) in Bulgaria, were selected as parents and the chemical mutagen EMS was used for generating mutations. In total, 1000 seeds were treated and the two generated M1 populations were grown in the field. All M2 mutant plants (1650 from initial line IP564 and 2420 from initial cultivar 'Mastilen 11b') were grown in field conditions and a number of phenotypic changes were observed on these mutated plants. They were also screened for Xap disease resistance via leaf artificial inoculation under greenhouse conditions. Individual plant selection was performed for the putatively resistant M2 plants. In the M3 generation these lines were screened using artificial inoculation with Xap and Psp pathogens (leaves and pods) under field conditions. Selected M3-M4 lines with confirmed disease resistance were tested for fresh pod quality. Yield tests were started in M4 and M5 generations and, according to their productivity performance, mutants were advanced to the M6/M7 generation for validation. The expression patterns of genes putatively involved in the resistance reactions towards two races of Psp were determined using qRT-PCR for the specific and reference genes. In conclusion, 50 plants with visible morphological changes and/or increased tolerance to the two targeted bacterial diseases were selected. A total of 20 advanced mutant bean lines are currently being evaluated for their competitiveness in multiple sites.
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"Concepts of Molecular Plant Breeding and Genome Editing." In Advances in Environmental Engineering and Green Technologies, 1–15. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4312-2.ch001.
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Traditional plant breeding depends on spontaneous and induced mutations available in the crop plants. Such mutations are rare and occur randomly. By contrast, molecular breeding and genome editing are advanced breeding techniques that can enhance the selection process and produce precisely targeted modifications in any crop. Identification of molecular markers, based on SSRs and SNPs, and the availability of high-throughput (HTP) genotyping platforms have accelerated the process of generating dense genetic linkage maps and thereby enhanced application of marker-assisted breeding for crop improvement. Advanced molecular biology techniques that facilitate precise, efficient, and targeted modifications at genomic loci are termed as “genome editing.” The genome editing tools include “zinc-finger nucleases (ZNFs),” “transcription activator-like effector nucleases (TALENs),” oligonucleotide-directed mutagenesis (ODM), and “clustered regularly interspersed short palindromic repeats (CRISPER/Cas) system,” which can be used for targeted gene editing. Concepts of molecular plant breeding and genome editing systems are presented in this chapter.
Conference papers on the topic "Plant improvement (selection, breeding and genetic engineering)"
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Kusumi, Naohiro, David E. Goldberg, and Noriyuki Ichinose. "Genetic Algorithm-Based Searching Method for Piping Path Routing in Coal-Fired Boiler Buildings." In ASME 2011 Power Conference collocated with JSME ICOPE 2011. ASMEDC, 2011. http://dx.doi.org/10.1115/power2011-55374.
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Power plant design using digital engineering based on 3-D computer-aided design has become a mainstream technology because of possessing higher speed and improvement in design accuracy. To take a coal-fired boiler building as an example, it has many complex structures with several million parts including the boiler itself, large fans, steel structures, and piping in varying sizes. Therefore, it is not easy to maintain integrity of the whole design throughout all the many engineering processes. We have developed a smart design system for coal-fired boiler buildings to solve the integrity problem. This system is capable of creating and allocating 3-D models automatically in accordance with various technical specifications and engineering rules. Lately, however, there has been a growing demand for more effectiveness of the developed system. We have begun to look into the feasibility of further improvements of the system function. The first point to note, when considering effectiveness, is the piping path routing process in the coal-fired boiler building. The quantity of piping is large, and it has a considerable impact on performance of the whole plant because hot steam is fed into the steam turbine and cold steam is taken from it through the piping. A considerable number of studies have been made on automatic searching methods of piping path routing. Although, the decision of piping path routing by using the Dynamic Programming method is most commonly, a previously decided routing becomes an interference object because of the single searching method. Therefore, basically, the later the order of the routing becomes, the longer the length of the routing becomes. To overcome this problem, in this paper we have proposed a new searching method based on the Genetic Algorithm (GA). The GA is a multipoint searching algorithm based on the mechanics of natural selection and natural genetics. Virtual prohibited cells are introduced into the proposed search method as a new idea. The virtual prohibited cells are located in a search space. The different paths are generated by avoiding the virtual prohibited cells while searching for the piping path routing. The optimum locations of the prohibited cells which are expressed in a genotype are obtained by using the GA in order to get a lot of paths independent of the order of the routing. The proposed method was evaluated using a simple searching problem. The results showed that many effective paths are generated by making the virtual prohibited cells.
Reports on the topic "Plant improvement (selection, breeding and genetic engineering)"
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Sherman, Amir, Rebecca Grumet, Ron Ophir, Nurit Katzir, and Yiqun Weng. Whole genome approach for genetic analysis in cucumber: Fruit size as a test case. United States Department of Agriculture, December 2013. http://dx.doi.org/10.32747/2013.7594399.bard.
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The Cucurbitaceae family includes a broad array of economically and nutritionally important crop species that are consumed as vegetables, staple starches and desserts. Fruit of these species, and types within species, exhibit extensive diversity as evidenced by variation in size, shape, color, flavor, and others. Fruit size and shape are critical quality determinants that delineate uses and market classes and are key traits under selection in breeding programs. However, the underlying genetic bases for variation in fruit size remain to be determined. A few species the Cucurbitaceae family were sequenced during the time of this project (cucumber was already sequenced when the project started watermelon and melon sequence became available during the project) but functional genomic tools are still missing. This research program had three major goals: 1. Develop whole genome cucumber and melon SNP arrays. 2. Develop and characterize cucumber populations segregating for fruit size. 3. Combine genomic tools, segregating populations, and phenotypic characterization to identify loci associated with fruit size. As suggested by the reviewers the work concentrated mostly in cucumber and not both in cucumber and melon. In order to develop a SNP (single nucleotide polymorphism) array for cucumber, available and newly generated sequence from two cucumber cultivars with extreme differences in shape and size, pickling GY14 and Chinese long 9930, were analyzed for variation (SNPs). A large set of high quality SNPs was discovered between the two parents of the RILs population (GY14 and 9930) and used to design a custom SNP array with 35000 SNPs using Agilent technology. The array was validated using 9930, Gy14 and F1 progeny of the two parents. Several mapping populations were developed for linkage mapping of quantitative trait loci (QTL) for fruit size These includes 145 F3 families and 150 recombinant inbred line (RILs F7 or F8 (Gy14 X 9930) and third population contained 450 F2 plants from a cross between Gy14 and a wild plant from India. The main population that was used in this study is the RILs population of Gy14 X 9930. Phenotypic and morphological analyses of 9930, Gy14, and their segregating F2 and RIL progeny indicated that several, likely independent, factors influence cucumber fruit size and shape, including factors that act both pre-anthesis and post-pollination. These include: amount, rate, duration, and plane of cell division pre- and post-anthesis and orientation of cell expansion. Analysis of F2 and RIL progeny indicated that factors influencing fruit length were largely determined pre-anthesis, while fruit diameter was more strongly influenced by environment and growth factors post-anthesis. These results suggest involvement of multiple genetically segregating factors expected to map independently onto the cucumber genome. Using the SNP array and the phenotypic data two major QTLs for fruit size of cucumber were mapped in very high accuracy (around 300 Kb) with large set of markers that should facilitate identification and cloning of major genes that contribute to fruit size in cucumber. In addition, a highly accurate haplotype map of all RILS was created to allow fine mapping of other traits segregating in this population. A detailed cucumber genetic map with 6000 markers was also established (currently the most detailed genetic map of cucumber). The integration of genetics physiology and genomic approaches in this project yielded new major infrastructure tools that can be used for understanding fruit size and many other traits of importance in cucumber. The SNP array and genetic population with an ultra-fine map can be used for future breeding efforts, high resolution mapping and cloning of traits of interest that segregate in this population. The genetic map that was developed can be used for other breeding efforts in other populations. The study of fruit development that was done during this project will be important in dissecting function of genes that that contribute to the fruit size QTLs. The SNP array can be used as tool for mapping different traits in cucumber. The development of the tools and knowledge will thus promote genetic improvement of cucumber and related cucurbits.