Letteratura scientifica selezionata sul tema "Citrus Genetics"
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Articoli di riviste sul tema "Citrus Genetics"
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Lyrene, Paul M. "Citrus: Genetics, Breeding and Biotechnology". HortScience 43, n. 6 (ottobre 2008): 1932a—1932. http://dx.doi.org/10.21273/hortsci.43.6.1932a.
Testo completo
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Gmitter, Frederick G. "Contemporary Approaches to Improving Citrus Cultivars". HortTechnology 4, n. 3 (luglio 1994): 206–10. http://dx.doi.org/10.21273/horttech.4.3.206.
Testo completoAbstract (sommario):
Traditional genetic manipulation methods have proven ineffective or irrelevant for many citrus breeding objectives. Alternative approaches to Citrus genetic improvement are now available as a result of technological developments in genetics and tissue culture. For example, mapping DNA marker polymorphisms should lead to identifying markers closely linked to important loci, thereby facilitating early selection and minimizing costs associated with plant size and juvenility. Genetic transformation methods allow trait-specific modification of commercial cultivars. By selecting beneficial variants from sectored fruit chimeras and the recovering plants via somatic embryogenesis, the problems of nucellar embryony and the hybrid nature of commercial cultivar groups can be avoided. Induced mutagenesis from mature vegetative buds may overcome these problems, as well as juvenility. Ploidy level manipulation in vitro can increase the number and diversity of tetraploid breeding parents, leading to the development of seedless Citrus triploids and mitigating sterility, incompatibility, and nucellar embryony.
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Talon, Manuel, e Fred G. Gmitter. "Citrus Genomics". International Journal of Plant Genomics 2008 (19 maggio 2008): 1–17. http://dx.doi.org/10.1155/2008/528361.
Testo completoAbstract (sommario):
Citrus is one of the most widespread fruit crops globally, with great economic and health value. It is among the most difficult plants to improve through traditional breeding approaches. Currently, there is risk of devastation by diseases threatening to limit production and future availability to the human population. As technologies rapidly advance in genomic science, they are quickly adapted to address the biological challenges of the citrus plant system and the world's industries. The historical developments of linkage mapping, markers and breeding, EST projects, physical mapping, an international citrus genome sequencing project, and critical functional analysis are described. Despite the challenges of working with citrus, there has been substantial progress. Citrus researchers engaged in international collaborations provide optimism about future productivity and contributions to the benefit of citrus industries worldwide and to the human population who can rely on future widespread availability of this health-promoting and aesthetically pleasing fruit crop.
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Gmitter, Frederick G. "CONTEMPORARY APPROACHES TO CITRUS CULTIVAR IMPROVEMENT". HortScience 27, n. 6 (giugno 1992): 699b—699. http://dx.doi.org/10.21273/hortsci.27.6.699b.
Testo completoAbstract (sommario):
Traditional methods of genetic manipulation have proven ineffective or irrelevant for many citrus breeding objectives. Alternative approaches to genetic improvement of citrus are now available as a result of technological developments in genetics and tissue culture. Mapping DNA markers on the Citrus genome should lead to identification of markers closely linked to important loci, thereby facilitating early selection and minimizing costs associated with plant size and juvenility. Genetic transformation methods provide opportunities for trait-specific modification of commercial cultivars. The selection of beneficial variants from sectored fruit chimeras, and the recovery of plants via somatic embryogenesis, can overcome the problems of nucellar embryony and the hybrid nature of commercial cultivar groups. Induced mutagenesis, using mature vegetative buds, may overcome size and juvenility, as well as nucellar embryony and hybridity. Ploidy level manipulation in vitro provides methods to overcome sterility, incompatibility, and nucellar embryony, and it can increase the number and diversity of tetraploid breeding parents available for development of seedless citrus triploids.
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Omura, Mitsuo, e Takehiko Shimada. "Citrus breeding, genetics and genomics in Japan". Breeding Science 66, n. 1 (2016): 3–17. http://dx.doi.org/10.1270/jsbbs.66.3.
Testo completo
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Donmez, Dicle, Ozhan Simsek, Tolga Izgu, Yildiz Aka Kacar e Yesim Yalcin Mendi. "Genetic Transformation inCitrus". Scientific World Journal 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/491207.
Testo completoAbstract (sommario):
Citrus is one of the world’s important fruit crops. Recently, citrus molecular genetics and biotechnology work have been accelerated in the world. Genetic transformation, a biotechnological tool, allows the release of improved cultivars with desirable characteristics in a shorter period of time and therefore may be useful in citrus breeding programs.Citrustransformation has now been achieved in a number of laboratories by various methods.Agrobacterium tumefaciensis used mainly in citrus transformation studies. Particle bombardment, electroporation,A. rhizogenes, and a new method called RNA interference are used in citrus transformation studies in addition toA. tumefaciens. In this review, we illustrate how different gene transformation methods can be employed in different citrus species.
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Elleuch, Amine, Fattouma Djilani Khouaja, Imen Hamdi, Nabiha Bsais, Jean-Pierre Perreault, Mohamed Marrakchi e Hatem Fakhfakh. "Sequence analysis of three citrus viroids infecting a single Tunisian citrus tree (Citrus, reticulata, Clementine)". Genetics and Molecular Biology 29, n. 4 (2006): 705–10. http://dx.doi.org/10.1590/s1415-47572006000400020.
Testo completo
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Gmitter, Fred G., Chunxian Chen, Marcos A. Machado, Alessandra Alves de Souza, Patrick Ollitrault, Yann Froehlicher e Tokurou Shimizu. "Citrus genomics". Tree Genetics & Genomes 8, n. 3 (26 aprile 2012): 611–26. http://dx.doi.org/10.1007/s11295-012-0499-2.
Testo completo
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Brune, Andreas, Mathias Müller, Lincoln Taiz, Pedro Gonzalez e Ed Etxeberria. "Vacuolar Acidification in Citrus Fruit: Comparison between Acid Lime (Citrus aurantifolia) and Sweet Lime (Citrus limmetioides) Juice Cells". Journal of the American Society for Horticultural Science 127, n. 2 (marzo 2002): 171–77. http://dx.doi.org/10.21273/jashs.127.2.171.
Testo completoAbstract (sommario):
Vacuolar acidification was investigated in `Palestine' sweet (Citrus limmetioides Tanaka) and `Persian' acid lime [(Citrus aurantifolia (Christm.) Swingle] (vacuolar pHs of 5.0 and 2.1, respectively) using tonoplast vesicles isolated from juice cells. The ATPase activity of tonoplast-enriched vesicles from sweet limes was strongly inhibited by bafilomycin A1 and NO3-, but was unaffected by vanadate. In contrast, the ATPase activity in acid lime membranes was only slightly inhibited by bafilomycin A1 and NO3- and was strongly inhibited by high concentrations of vanadate. The vacuolar origin of the acid lime vesicles was confirmed by immunoblotting. After solubilization and partial purification of the two enzymes by gel filtration, their inhibitor profiles were largely unchanged. Based on equal ATPase activities, vesicles from sweet and acid limes were able to generate similar pH gradients. However, in tonoplast vesicles from sweet limes, the maximum ΔpH was reached four times faster than in those from acid limes. Addition of ethylenediamine tetraacetic acid (EDTA) to chelate Mg+2 after the maximal ΔpH was attained resulted in collapse of the pH gradient in vesicles from sweet limes, whereas no change in ΔpH was observed in vesicles from acid limes, indicating a less H+ permeable membrane. Vacuolar ATPases from both cultivars exhibited identical pH optima and showed similar Mg+2 dependence, but only the acid lime ATPase activity was inhibited by Ca+2. These data confirm that the vanadate-sensitive form of the V-ATPase found in lemon and acid limes is specific to hyperacidifying tissues rather than to citrus juice cells. Sweet lime vacuoles bear the classical V-ATPase also found in vegetative plant tissues.
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Yu, Yuan, Chunxian Chen, Ming Huang, Qibin Yu, Dongliang Du, Matthew R. Mattia e Frederick G. Gmitter. "Genetic Diversity and Population Structure Analysis of Citrus Germplasm with Single Nucleotide Polymorphism Markers". Journal of the American Society for Horticultural Science 143, n. 6 (novembre 2018): 399–408. http://dx.doi.org/10.21273/jashs04394-18.
Testo completoAbstract (sommario):
Citrus (Citrus sp.) germplasm collections are a valuable resource for citrus genetic breeding studies, and further utilization of the resource requires knowledge of their genotypic and phylogenetic relationships. Diverse citrus accessions, including citron (Citrus medica), mandarin (Citrus reticulata), pummelo (Citrus maxima), papeda (Papeda sp.), trifoliate orange (Poncirus trifoliata), kumquat (Fortunella sp.), and related species, have been housed at the Florida Citrus Arboretum, Winter Haven, FL, but the accessions in the collection have not been genotyped. In this study, a collection of 80 citrus accessions were genotyped using 1536 sweet orange–derived single nucleotide polymorphism (SNP) markers, to determine their SNP fingerprints and to assess genetic diversity, population structure, and phylogenetic relationships, and thereby to test the efficiency of using the single genotype-derived SNP chip with relatively low cost for these analyses. Phylogenetic relationships among the 80 accessions were determined by multivariate analysis. A model-based clustering program detected five basic groups and revealed that C. maxima introgressions varied among mandarin cultivars and segregated in mandarin F1 progeny. In addition, reciprocal differences in C. maxima contributions were observed among citranges (Citrus sinensis × P. trifoliata vs. P. trifoliata × C. sinensis) and may be caused by the influence of cytoplasmic DNA and its effect on selection of cultivars. Inferred admixture structures of many secondary citrus species and important cultivars were confirmed or revealed, including ‘Bergamot’ sour orange (Citrus aurantium), ‘Kinkoji’ (C. reticulata × Citrus paradisi), ‘Hyuganatsu’ orange (Citrus tamurana), and palestine sweet lime (Citrus aurantifolia). The relatively inexpensive SNP array used in this study generated informative genotyping data and led to good consensus and correlations with previously published observations based on whole genome sequencing (WGS) data. The genotyping data and the phylogenetic results may facilitate further exploitation of interesting genotypes in the collection and additional understanding of phylogenetic relationships in citrus.
Tesi sul tema "Citrus Genetics"
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Ashari, Ir Sumeru. "Discrimination between citrus genotypes". Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09A/09aa819.pdf.
Testo completo
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Silva, Cristina Lacerda Soares Petrarolha [UNESP]. "Apomixia em citros: expressão diferencial de mRNA e proteínas em plântulas e embriões zigóticos e apomíticos". Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/102846.
Testo completoAbstract (sommario):
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silva_clsp_dr_jabo.pdf: 887183 bytes, checksum: 044073bedd049b3dbdbbffe36499be0b (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A apomixia, ou seja a produção de sementes clonais, possuindo embriões idênticos à planta mãe, é um processo controlado geneticamente. Na apomixia facultativa, ocorrente no gênero Citrus, verifica-se a coexistência da reprodução sexual e apomítica em um mesmo óvulo. Entretanto os eventos genéticos que desencadeiam a produção de embriões apomíticos são atualmente pouco conhecidos. Não se sabe ainda, se os mesmos genes responsáveis pela formação dos embriões zigóticos, também seriam os responsáveis pela formação dos embriões apomíticos, expressando-se entretanto, de forma diferente. Outra possibilidade é a existência de genes particulares responsáveis pelo evento apomítico, mas é improvável que este locus envolva novas e distintas vias metabólicas que incluam novos genes para a formação do saco embrionário e para a embriogênese. Uma possibilidade é que a reprodução apomítica seja uma consequência da expressão de um gene que funciona iniciando uma cascata de ações gênicas em diferentes momentos durante o curso dos eventos sexuais no óvulo. Conhecidamente as proteínas de reserva são codificadas por genes, que se expressam de forma tecido específico, constituindo-se em excelente material para estudos de eventos genéticos. Com o objetivo de detectar particularidades genéticas do processo apomítico em Citrus, estudou-se, a nível de mRNA e proteínas, a expressão diferencial de embriões zigóticos, embriões apomíticos e plântulas zigóticas de espécies de Citrus. A condição apomítica ou zigótica dos embriões e plântulas estudados, foi avaliada empregando-se marcadores moleculares do tipo RAPD e fAFLP. Verificou-se que ambos os tipos de embriões, e de plântulas, expressam um grupo de proteínas diferencialmente. A nível de mRNA detectou-se expressão diferencial tanto para a condição zigótica, quanto para a apomítica...
Apomixis or clonal seed production with mother identical embryos is a process genetically controlled. On the facultative apomixy, that takes place in the genus Citrus it is possible to observe the co-existence of sexual and apomitical reproduction on the same ovulum. However the genetic events that trigger the apomitical embryo production are presently poorly known. It is still not known if the same genes related to the zygotic embryo formation would be the same related to the formation of the apomitic embryos, exhibiting different expression patterns. Another possibility is the existence of a particular set of genes that would be responsible for the apomitic event but, it is rather improbable that such locus would control new and distinct metabolic pathways that include the action of new genes related to the formation of the embryonic sac and other set of genes for the embryogenesis itself. One should also consider that the apomitic reproduction might be a consequence of erratic gene expression of a gene that acts triggering a successive set of genetic activities on different occasions during the course of the ovulum sexual processes. The reserve proteins are coded by genes that express on specific tissues, making up a set of excellent material for genetic studies. Aiming to study such genetic particularities on the Citrus apomitic process, it was carried out a study on the differential expression of mRNA and their corresponding reserve protein using zygotic, apomitic and zygotic plants. The apomitical and zygotic embryonic conditions together with those related to early developed seedlings were evaluated using molecular markers such as RAPD, fAFLP. It was observed that both types of embryos and seedlings express a set of differential proteins... (complete abstract, access undermentioned eletronic adress)
3
Ellis, Danielle René. "Characterization of a citrus vascular-specific zinc-binding cysteine proteinase inhibitor". Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/298754.
Testo completoAbstract (sommario):
A 712 bp partial cDNA clone (czbp- 1) of the citrus vascular zinc binding protein (CVZBP) was isolated using reverse transcriptase polymerase chain reaction (RT-PCR). The deduced amino acid sequence of czbp-1 was identical to the N-terminal amino acid sequence for the CVZBP. Czbp- 1 had a 549 bp open reading frame and two putative polyadenylation sites, +20 bp and +103 bp relative to the poly-A tail. The deduced amino acid sequence had identity with members of the Kunitz soybean proteinase inhibitor (KSPI) family. Many members of this family are present in high concentrations in storage organs such as seeds and tubers, increase in response to abiotic stress, and are considered defense or stress response proteins. The CVZBP did not appear to fit in this category. Unlike many members of the KSPI family CVZBP was not detected in citrus seeds and protein levels decreased in response to wounding. Transcript also decreased in response to osmotic stress; a similar result previously was reported for CVZBP protein levels. Accumulation of CVZBP and its transcript increased in Zn deficient citrus seedlings compared to those receiving sufficient levels of Zn, indicating that Zn nutrition can modulate CVZBP expression. Recombinant CVZBP was produced and used to determine the capacity of this protein to inhibit several types of proteinases. The CVZBP inhibited the cysteine proteinase, papain, but not the serine proteinases, trypsin and chymotrypsin. CVZBP protein was immunolocalized primarily to the xylem parenchyma in vascular tissue of citrus midribs. Based on these results it is possible that the CVZBP has a function in vascular differentiation. Cysteine proteinases were identified in developing tracheary elements in Zinnia cell cultures. Addition of inhibitors of cysteine proteinase to these cultures prior to secondary cell wall deposition prevents differentiation of the cells into tracheary elements. Perhaps cysteine proteinase inhibitors, such as the CVZBP, in the xylem, contribute to timing of tracheary element differentiation and determination.
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Lee, Suk-wah, e 李淑華. "Fungicide resistance and genetic diversity of Penicillium digitatum inHong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31226255.
Testo completo
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Muniz, Fabiana Rezende. "Caracterização molecular e avaliação da resistência ao vírus da tristeza dos citros (CTV) em plantas transgênicas de laranja \'Valência\' (Citrus sinensis L. Osbeck)". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-10022009-094528/.
Testo completoAbstract (sommario):
No Brasil a citricultura está entre as culturas de maior importância. A produtividade dessa cultura no país ainda é considerada baixa e esse fato se deve, em parte, a diversas pragas e doenças. Dentre as doenças, tem-se a tristeza, causada pelo Citrus tristeza virus (CTV). Esse patógeno também pode estar relacionado com outra importante doença da cultura, a morte súbita dos citros (MSC). Com isso, o CTV ganhou ainda maior expressão. Uma alternativa para controlar viroses de plantas é a obtenção de plantas transgênicas resistentes a esses patógenos. Este trabalho objetivou caracterizar com análise molecular e avaliar a resistência ao CTV de plantas transgênicas de laranja Valência (Citrus sinensis L. Osbeck), contendo fragmentos do genoma do CTV, em três construções gênicas diferentes. A transgenia das plantas foi confirmada por análises de Southern blot. A transcrição do transgene foi avaliada por RT-PCR. O material foi inoculado com duas borbulhas infectadas pelo isolado Pêra- IAC, enxertadas no porta-enxerto abaixo do ponto de enxertia da copa transgênica, e pelo vetor Toxoptera citricida infectado. Após quatro semanas da inoculação, para avaliar a resistência ao vírus, brotações da copa transgênica foram submetidas ao teste de ELISA sanduíche indireto com anticorpo monoclonal contra a proteína da capa protéica do CTV. Os resultados indicaram variação na resistência à translocação do vírus nas diferentes construções transgênicas utilizadas e entre clones de uma mesma planta. Todas as linhagens transgênicas inoculadas indicaram a presença do vírus em pelo menos uma das três repetições avaliadas, quando inoculadas por enxertia. Quando inoculadas pelo vetor algumas plantas apresentaram todos os seus clones com baixos valores de absorbância, indicando uma possível resistência ao patógeno.In Brazil, citrus is one of the most important cultures. The productivity of this culture in the country is still considered low and this fact is due to several pests and diseases that affect the crop. Among the diseases there is the tristeza, caused by Citrus tristeza virus (CTV). This pathogen can also be related with another important disease, the citrus sudden death. Therefore, CTV acquired much more significance. This work aimed to characterize with molecular analysis and to evaluate the resistance to CTV of transgenic Valência plants (Citrus sinensis L. Osbeck), containing genomic fragments of CTV, in three different transgenic constructs. The plants were confirmed as transgenic by Southern blot. The transcription of the transgene was evaluated by RT-PCR. The transgenic plants were challenged with a weak strain of CTV, CTV-IAC, by bud inoculation with two infected bubbles, and by the infected vector Toxoptera citricida. After four weeks of inoculation, the evaluation of viral replication in the transgenic seious was done by ELISA indirect sandwich with monoclonal antibody against the CTV coat protein. The results indicated variation of the resistance to the translocation of the virus between the different transgenic constructs used and between clones of the same plant. All the inoculated plants indicated the presence of the virus in, at least, one of the three evaluated clones, when inoculated by grafting. When inoculated by the vector some plants had all their clones with low values of virus, indicating a possible resistance to the pathogen.
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Silva, Cristina Lacerda Soares Petrarolha. "Apomixia em citros : expressão diferencial de mRNA e proteínas em plântulas e embriões zigóticos e apomíticos /". Jaboticabal : [s.n.], 2002. http://hdl.handle.net/11449/102846.
Testo completoAbstract (sommario):
Orientadora: Eliana Gertrudes Macedo LemosBanca: João Martins Pizauro Júnior
Banca: Jesus Aparecido Ferro
Banca: Marcos Antônio Machado
Banca: Mario Sérgio Palma
Resumo: A apomixia, ou seja a produção de sementes clonais, possuindo embriões idênticos à planta mãe, é um processo controlado geneticamente. Na apomixia facultativa, ocorrente no gênero Citrus, verifica-se a coexistência da reprodução sexual e apomítica em um mesmo óvulo. Entretanto os eventos genéticos que desencadeiam a produção de embriões apomíticos são atualmente pouco conhecidos. Não se sabe ainda, se os mesmos genes responsáveis pela formação dos embriões zigóticos, também seriam os responsáveis pela formação dos embriões apomíticos, expressando-se entretanto, de forma diferente. Outra possibilidade é a existência de genes particulares responsáveis pelo evento apomítico, mas é improvável que este locus envolva novas e distintas vias metabólicas que incluam novos genes para a formação do saco embrionário e para a embriogênese. Uma possibilidade é que a reprodução apomítica seja uma consequência da expressão de um gene que funciona iniciando uma cascata de ações gênicas em diferentes momentos durante o curso dos eventos sexuais no óvulo. Conhecidamente as proteínas de reserva são codificadas por genes, que se expressam de forma tecido específico, constituindo-se em excelente material para estudos de eventos genéticos. Com o objetivo de detectar particularidades genéticas do processo apomítico em Citrus, estudou-se, a nível de mRNA e proteínas, a expressão diferencial de embriões zigóticos, embriões apomíticos e plântulas zigóticas de espécies de Citrus. A condição apomítica ou zigótica dos embriões e plântulas estudados, foi avaliada empregando-se marcadores moleculares do tipo RAPD e fAFLP. Verificou-se que ambos os tipos de embriões, e de plântulas, expressam um grupo de proteínas diferencialmente. A nível de mRNA detectou-se expressão diferencial tanto para a condição zigótica, quanto para a apomítica... (resumo completo, clicar no acesso eletrônico abaixo)
Abstract: Apomixis or clonal seed production with mother identical embryos is a process genetically controlled. On the facultative apomixy, that takes place in the genus Citrus it is possible to observe the co-existence of sexual and apomitical reproduction on the same ovulum. However the genetic events that trigger the apomitical embryo production are presently poorly known. It is still not known if the same genes related to the zygotic embryo formation would be the same related to the formation of the apomitic embryos, exhibiting different expression patterns. Another possibility is the existence of a particular set of genes that would be responsible for the apomitic event but, it is rather improbable that such locus would control new and distinct metabolic pathways that include the action of new genes related to the formation of the embryonic sac and other set of genes for the embryogenesis itself. One should also consider that the apomitic reproduction might be a consequence of erratic gene expression of a gene that acts triggering a successive set of genetic activities on different occasions during the course of the ovulum sexual processes. The reserve proteins are coded by genes that express on specific tissues, making up a set of excellent material for genetic studies. Aiming to study such genetic particularities on the Citrus apomitic process, it was carried out a study on the differential expression of mRNA and their corresponding reserve protein using zygotic, apomitic and zygotic plants. The apomitical and zygotic embryonic conditions together with those related to early developed seedlings were evaluated using molecular markers such as RAPD, fAFLP. It was observed that both types of embryos and seedlings express a set of differential proteins... (complete abstract, access undermentioned eletronic adress)
Doutor
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Soriano, Leonardo. "Organogênese in vitro e transformação genética de variedades de tangerina (Citrus reticulata Blanco e Citrus clementina hort. ex Tan.)". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-19052015-142119/.
Testo completoAbstract (sommario):
Atualmente, o Huanglongbing (HLB), doença associada à bactéria Candidatus Liberibacter spp., é a principal ameaça dos Citrus, não tendo sido encontrado ainda espécies resistentes e tolerantes. O melhoramento genético tradicional apresenta limitações para a obtenção de novas variedades porta-enxerto e copa de citros em decorrência a fatores ligados à biologia do gênero. Na tentativa de sobrepor essas dificuldades, a transformação genética destaca-se por permitir a introdução de genes exógenos, os quais, além de reduzir o período de obtenção de material melhorado geneticamente, poderão conferir resistência a doenças em variedades de interesse agronômico. Desse modo, o objetivo desta pesquisa consistiu no estudo da organogênese in vitro, e na obtenção de plantas transgênicas via Agrobacterium tumefaciens das tangerinas \'Fremont\', \'Thomas\' e \'Nules\', com o gene que codifica o peptídeo antibacteriano atacina A (attA), controlado pelos promotores AtSUC2 e AtPP2, visando a expressão gênica preferencial nos vasos do floema. Adicionalmente, foi avaliada a transformação genética via A. tumefaciens de suspensões celulares de tangerina \'W-Murcott\', de laranja doce \'Hamlin\' e de tangelo \'Page\', e a transformação genética direta via PEG de protoplastos da tangerina \'W-Murcott\', com os fatores de transcrição VvmybA1 e Ruby, dirigidos pelos promotores com expressão preferencial nos tecidos embrionários 6105 e DC3. A eficiência da organogênese in vitro foi influenciada pelo tipo de explante e concentração de BAP. Após os experimentos de transformação genética de segmentos de epicótilo e internodal das tangerinas \'Fremont\', \'Thomas\' e \'Nules\', as plantas regeneradas foram analisadas por PCR, Southern blot e RT-qPCR e confirmadas como transgênicas pela presença e transcrição do gene attA no tecido vascular. A transformação genética de suspensões celulares mostrou-se eficiente com alta produção de antocianina nos embriões somáticos regenerados de tangerina \'W-Murcott\', de laranja doce \'Hamlin\' e de tangelo \'Page\'. A transformação genética direta de protoplastos de tangerina \'W-Murcott\' mostrou-se viável e também foi possível a obtenção de embriões somáticos transgênicos. Os fatores de transcrição VvmybA1 e Ruby se mostraram úteis para detecção visual do material transgênicoCurrently, Huanglongbing (HLB), associated to Candidatus Liberibacter spp., is the main threat to the citrus culture. The conventional plant breeding shows limitations to the obtain new varieties of rootstock and scion, due to factors related to the biology of the genus. In attempt to overcome these barriers, genetic engineering is notable for allowing the introduction of foreign genes, which, besides reducing the time to obtain genetically improved material may confer disease resistance in varieties of agronomic interest. Thus, the objective of the research was the study of in vitro organogenesis, and obtain transgenic plants of \'Fremont\', \'Thomas\' and \'Nules\' mandarins via Agrobacterium tumefaciens with the gene encoding the antibacterial peptide attacin A (attA), controlled by the promoters AtSUC2 and AtPP2, aiming to preferential gene expression in phloem. In addition, the genetic transformation of cell suspensions, via A. tumefaciens, of \'W-Murcott\' mandarin, \'Hamlin\' sweet orange and \'Page\' tangelo and the direct genetic transformation, via PEG, of \'W-Murcott\' mandarin protoplasts were evaluated with VvmybA1 and Ruby transcription factors driven by 6105 and DC3 promoters, with preferential expression in embryonic tissues. The in vitro organogenesis of the varieties studied was influenced by the type of explant and BAP concentration. After genetic transformation experiments of epicotyl and internodal segments of \'Fremont\', \'Thomas\' and \'Nules mandarins, regenerated plants were analyzed by PCR, Southern blot and RT-qPCR and confirmed as transgenic by presence and transcription of attA gene. The genetic transformation of cell suspensions was efficient with high anthocyanin production in the somatic embryos regenerated of \'W-Murcott\' mandarin, \'Hamlin\' sweet orange and \'Page\' tangelo. The direct genetic transformation of \'W-Murcott\' mandarin protoplasts revealed to be viable and it was also possible to obtain transgenic somatic embryos. The VvmybA1 and Ruby transcription factors were useful tools for visual detection of transgenic material
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Francisco, Carolina Sardinha [UNESP]. "Estrutura de populações e inoculações recíprocas de Xylella fastidiosa subsp. pauca com ocorrência em cultivos vizinhos de Citrus sinensis e Coffea arabica sob condições do estado de São Paulo". Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/115645.
Testo completoAbstract (sommario):
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000811896.pdf: 967104 bytes, checksum: 63037b124f0b61a187940925ad4979e2 (MD5)A pouco mais de uma década a bactéria Xylella fastidiosa passou de um organismo pouco conhecido a uns dos mais conhecidos, ao menos em termos de genômica. No Brasil esta bactéria afeta culturas de importância econômica como citros, causando a clorose variegada dos citros (CVC) e café, na qual causa a requeima da folha do cafeeiro (RFC), também conhecida como atrofia do ramo do cafeeiro (ARC). Em laranjeiras a bactéria acarreta os maiores danos econômicos, na ordem de 100 milhões de dólares anuais. Em relação às plantas de café, estudos demonstraram que a cada 1% de aumento na severidade da doença há perdas de rendimento de 1,22 a 1,34 sacos de 60kg por hectare. Ambas as culturas são afetadas pela Xylella fastidiosa subsp. pauca e transmitida pelos mesmo vetores, porém ainda são incertas as informações se o isolado que causa a CVC pode colonizar cafeeiros e causar doença e vice-versa. Além do mais, em contraste com os diversos estudos já realizados sobre populações de X. fastidiosa infectando laranjeiras, não se tinha informações sobre a diversidade genética e estrutura populacional deste patógeno quando infectando cafeeiros. Um total de 618 estirpes de X. fastidiosa foi isolado de laranjeiras e cafeeiros de quatro regiões geográficas distintas do estado de São Paulo. Esses isolados foram genotipados através de 14 marcadores microssatélites. A alta diversidade genotípica e genética, os altos índices de clonalidade, o forte desequilíbrio gamético e o elevado grau de subdivisão populacional encontrados nas populações de X. fastidiosa amostradas de cafeeiros são consistentes com predominância de um modo de reprodução clonal. Os níveis de subdivisão observados poderiam ser explicados pela migração histórica assimétrica encontrada entre as populações, indicando as populações da região Noroeste e Central como as prováveis fundadoras. Também realizamos ensaios de inoculações recíprocas ...
A little over a decade the bacterium Xylella fastidiosa has gone from a little-known body to the most popular ones, at least in terms of genomics. In Brazil this bacterium affects economically important crops such as citrus, which causes citrus variegated chlorosis (CVC) and coffee, causing coffee leaf scorch (CLS), also known as coffee stem atrophy (CSA). In orange this bacteria causes major economic losses in the order of 100 million dollars annually. Regarding the coffee plants, studies have shown that every 1% increase in the severity of disease cause loss of 1.22 to 1.34 bags of 60kg per hectare. Both cultures are affected by subsp. pauca of X. fastidiosa and are transmitted by the same vectors, but informations are still uncertain if isolated causing CVC can colonize and cause disease in coffee plants and vice versa. Moreover, in contrast of many previous work on study about population of X. fastidiosa infecting orange, we had no information about genetic diversity and population structure of this pathogen infecting coffee plants. Thus a total of 618 strains of X. fastidiosa was isolated from orange and coffee in four distinct geographic regions (Central, Northwestern, Center-western and Eastern) of the São Paulo State. These isolates were typed by fourteen microsatellite markers. The high genotypic and genetic diversity, high levels of clonality, strong gametic disequilibrium, and the population subdivision found in X. fastidiosa population are consistent with the predominance of mode of clonal reproduction. The subdivision levels observed could be explained by the asymmetric historical migration between populations, indicating the populations of Central and Northwestern region as the probable founders. We also performed tests of reciprocal inoculations among isolates from orange and coffee plants under controlled conditions. The 99 isolates from orange and 127 isolates from coffee through Bayesian analysis, were grouped on ...
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Francisco, Carolina Sardinha. "Estrutura de populações e inoculações recíprocas de Xylella fastidiosa subsp. pauca com ocorrência em cultivos vizinhos de Citrus sinensis e Coffea arabica sob condições do estado de São Paulo /". Jaboticabal, 2014. http://hdl.handle.net/11449/115645.
Testo completoAbstract (sommario):
Orientador: Paulo Cezar CeresiniCoorientador: Helvécio Della Coletta Filho
Banca: Vitor Fernandes Oliveira de Miranda
Banca: Eduardo Seite Gomide Mizubuti
Resumo: A pouco mais de uma década a bactéria Xylella fastidiosa passou de um organismo pouco conhecido a uns dos mais conhecidos, ao menos em termos de genômica. No Brasil esta bactéria afeta culturas de importância econômica como citros, causando a clorose variegada dos citros (CVC) e café, na qual causa a requeima da folha do cafeeiro (RFC), também conhecida como atrofia do ramo do cafeeiro (ARC). Em laranjeiras a bactéria acarreta os maiores danos econômicos, na ordem de 100 milhões de dólares anuais. Em relação às plantas de café, estudos demonstraram que a cada 1% de aumento na severidade da doença há perdas de rendimento de 1,22 a 1,34 sacos de 60kg por hectare. Ambas as culturas são afetadas pela Xylella fastidiosa subsp. pauca e transmitida pelos mesmo vetores, porém ainda são incertas as informações se o isolado que causa a CVC pode colonizar cafeeiros e causar doença e vice-versa. Além do mais, em contraste com os diversos estudos já realizados sobre populações de X. fastidiosa infectando laranjeiras, não se tinha informações sobre a diversidade genética e estrutura populacional deste patógeno quando infectando cafeeiros. Um total de 618 estirpes de X. fastidiosa foi isolado de laranjeiras e cafeeiros de quatro regiões geográficas distintas do estado de São Paulo. Esses isolados foram genotipados através de 14 marcadores microssatélites. A alta diversidade genotípica e genética, os altos índices de clonalidade, o forte desequilíbrio gamético e o elevado grau de subdivisão populacional encontrados nas populações de X. fastidiosa amostradas de cafeeiros são consistentes com predominância de um modo de reprodução clonal. Os níveis de subdivisão observados poderiam ser explicados pela migração histórica assimétrica encontrada entre as populações, indicando as populações da região Noroeste e Central como as prováveis fundadoras. Também realizamos ensaios de inoculações recíprocas ...
Abstract: A little over a decade the bacterium Xylella fastidiosa has gone from a little-known body to the most popular ones, at least in terms of genomics. In Brazil this bacterium affects economically important crops such as citrus, which causes citrus variegated chlorosis (CVC) and coffee, causing coffee leaf scorch (CLS), also known as coffee stem atrophy (CSA). In orange this bacteria causes major economic losses in the order of 100 million dollars annually. Regarding the coffee plants, studies have shown that every 1% increase in the severity of disease cause loss of 1.22 to 1.34 bags of 60kg per hectare. Both cultures are affected by subsp. pauca of X. fastidiosa and are transmitted by the same vectors, but informations are still uncertain if isolated causing CVC can colonize and cause disease in coffee plants and vice versa. Moreover, in contrast of many previous work on study about population of X. fastidiosa infecting orange, we had no information about genetic diversity and population structure of this pathogen infecting coffee plants. Thus a total of 618 strains of X. fastidiosa was isolated from orange and coffee in four distinct geographic regions (Central, Northwestern, Center-western and Eastern) of the São Paulo State. These isolates were typed by fourteen microsatellite markers. The high genotypic and genetic diversity, high levels of clonality, strong gametic disequilibrium, and the population subdivision found in X. fastidiosa population are consistent with the predominance of mode of clonal reproduction. The subdivision levels observed could be explained by the asymmetric historical migration between populations, indicating the populations of Central and Northwestern region as the probable founders. We also performed tests of reciprocal inoculations among isolates from orange and coffee plants under controlled conditions. The 99 isolates from orange and 127 isolates from coffee through Bayesian analysis, were grouped on ...
Mestre
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Mallampalli, Venkata K. P. S. "Expression and Biochemical Function of Putative Flavonoid GT Clones from Grapefruit and Identification of New Clones using the harvEST Database". Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etd/1788.
Testo completoAbstract (sommario):
Flavonoids are plant secondary metabolites well known for many key roles in the life cycle of plants. They also can affect human health. Citrus paradisi is known to produce several glucosylated flavonoids and these compounds are glucosylated by enzymes known as glucosyltransferases (GTs). The focus of this research was to optimize the heterologous expression, enrichment, and biochemical characterization of grapefruit putative GT protein, PGT2, and to test the hypothesis that PGT2 is a flavonoid GT. Results showed detectable amounts of activity with quercetin, a flavonol; however, activity was lower than what would be expected if this enzyme were a flavonol-specific GT. In an additional aspect of this study, bioinformatics were used to test the hypothesis that additional putative GT clones could be identified using the harvEST database.
Libri sul tema "Citrus Genetics"
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Khan, I. A., a cura di. Citrus genetics, breeding and biotechnology. Wallingford: CABI, 2007. http://dx.doi.org/10.1079/9780851990194.0000.
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Plant Genome Data and Information Center (U.S.). 6 citrus nucleic acid sequences. Beltsville, MD: Plant Genome Data and Information Center, NAL, USDA, 1994.
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Nobumasa, Nito. Status report on genetic resources of citrus in Asia-Pacific region. New Delhi: IPGRI Office for South Asia, 2000.
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B, Kristiansen, Linden Joan e Mattey Michael, a cura di. Citric acid biotechnology. London: Taylor & Francis, 1999.
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Bacigalupi, Paolo. The drowned cities. New York: Little, Brown and Company, 2012.
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Simak, Clifford D. City. London: Methuen Paperback, 1988.
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Simak, Clifford D. City. New York: Macmillan Pub. Co., 1991.
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Simak, Clifford D. City. New York, NY: Macmillan, 1991.
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Brand, Stewart. Whole earth discipline: Why dense cities, nuclear power, transgenic crops, restored wildlands and geoengineering are necessary. New York: Penguin, 2010.
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International Horticultural Congress (26th 2002 Toronto, Ont.). A proceedings of the XXVI International Horticultural Congress, Toronto, Canada, 11-17 August, 2002: Asian plants with unique horticultural potential : genetic resources, cultural practices, and utilization. A cura di Lee Jung-Myung, Zhang Donglin, Canadian Society for Horticultural Science. e International Society for Horticultural Science. Leuven, Belgium: International Society for Horticultural Science, 2003.
Cerca il testo completoCapitoli di libri sul tema "Citrus Genetics"
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Cuenca, José, Andrés Garcia-Lor, Luis Navarro e Pablo Aleza. "Citrus Genetics and Breeding". In Advances in Plant Breeding Strategies: Fruits, 403–36. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-91944-7_11.
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Wood, R. J. "Genetics applied to the control of insect pests". In Integrated Pest Control in Citrus-Groves, 505–16. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003079279-77.
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Ollitrault, Patrick, Maria Antonietta Germanà, Yann Froelicher, Jose Cuenca, Pablo Aleza, Raphaël Morillon, Jude W. Grosser e Wenwu Guo. "Ploidy Manipulation for Citrus Breeding, Genetics, and Genomics". In Compendium of Plant Genomes, 75–105. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-15308-3_6.
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Sarkar, Rohan, Aditi Kundu, Anirban Dutta, Abhishek Mandal e Supradip Saha. "Citrus Peel as a Source for Waste Valorization and Its Greener Processing". In Melon Breeding and Genetics: Developments in Food Quality & Safety, 147–74. Washington, DC: American Chemical Society, 2022. http://dx.doi.org/10.1021/bk-2022-1415.ch011.
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Akimitsu, K., A. Isshiki, K. Ohtani, M. Ishikawa e H. Yamamoto. "Biochemical and Molecular Roles of HST and Enzymes Produced by Pathogen of Citrus Brown Spot Disease". In Molecular Genetics of Host-Specific Toxins in Plant Disease, 281–90. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5218-1_31.
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Graniti, A. "Toxins and other Metabolites of Phoma Tracheiphila Involved in Pathogenesis of “Mal Secco” Disease of Citrus Trees". In Molecular Genetics of Host-Specific Toxins in Plant Disease, 195–97. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5218-1_23.
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Barbhuiya, A. R., Mohammed Latif Khan e S. Dayanandan. "Molecular Phylogeny of Citrus species in the Eastern Himalayan Region of Northeast India Based on Chloroplast and Nuclear DNA Sequence Data". In Molecular Genetics and Genomics Tools in Biodiversity Conservation, 185–201. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-6005-4_9.
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Usman, Muhammad, Iqrar A. Rana, Shahnawaz-ul-Rehman, Bilquees Fatima e Muhammad Sarwar Khan. "Citrus Genetic Resources". In Citrus Production, 73–93. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003119852-5.
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Cimen, Berken, Turgut Yesiloglu, Bilge Yilmaz e Meral Incesu. "Genetic Improvement in Citrus". In Citrus Production, 35–49. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003119852-3.
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Moore, G. A., D. Luth, F. Kaplan e M. A. Gutiérrez-E. "Genetic Transformation in Citrus". In Molecular Biology of Woody Plants, 227–43. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-017-2313-8_11.
Testo completoAtti di convegni sul tema "Citrus Genetics"
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Mariana, Baiq Dina, Anis Andrini e Sri Andayani. "Identifying potential seedless citrus accessions through floral structure and pollen performance". In THE SECOND INTERNATIONAL CONFERENCE ON GENETIC RESOURCES AND BIOTECHNOLOGY: Harnessing Technology for Conservation and Sustainable Use of Genetic Resources for Food and Agriculture. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0076922.
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Alba, Enrique. "Intelligent Systems for Smart Cities". In GECCO '15: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2739482.2756563.
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Alba, Enrique. "Intelligent systems for smart cities". In GECCO '17: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2017. http://dx.doi.org/10.1145/3067695.3067727.
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Alba, Enrique. "Intelligent Systems for Smart Cities". In GECCO '16: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2908961.2927000.
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Chebbi, Olfa, e Nouha Nouri. "Reducing Energy Consumption in Smart Cities". In GECCO '16: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2908961.2931637.
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Stolfi, Daniel H., e Enrique Alba. "Eco-friendly reduction of travel times in european smart cities". In GECCO '14: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2014. http://dx.doi.org/10.1145/2576768.2598317.
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Stolfi, Daniel H., Rolando Armas, Enrique Alba, Hernan Aguirre e Kiyoshi Tanaka. "Fine Tuning of Traffic in our Cities with Smart Panels". In GECCO '16: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2908812.2908868.
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Agisimanto, Dita, Farida Yulianti e Hidayatul Arisah. "Cells density affects cell production of Citrus limonia in flask and air-lift bioreactor cultures and limonin farming". In THE SECOND INTERNATIONAL CONFERENCE ON GENETIC RESOURCES AND BIOTECHNOLOGY: Harnessing Technology for Conservation and Sustainable Use of Genetic Resources for Food and Agriculture. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0075651.
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Galán-Franco, A. L., K. Arévalo-Niño, M. Elías-Santos, A. Morales-Loredo, G. Alvarez-Ojeda, J. I. López-Arroyo e I. Quintero-Zapata. "Genetic variability analysis of entomopathogenic fungi isolated from citrus-growing areas of Mexico". In Proceedings of the III International Conference on Environmental, Industrial and Applied Microbiology (BioMicroWorld2009). WORLD SCIENTIFIC, 2010. http://dx.doi.org/10.1142/9789814322119_0013.
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Guoxiang, Tang, Qu Ming, Wang Xuan e Lv Jiake. "A parameter selection of support vector machine with genetic algorithm for citrus quality classification". In Education (ICCSE 2011). IEEE, 2011. http://dx.doi.org/10.1109/iccse.2011.6028661.
Testo completoRapporti di organizzazioni sul tema "Citrus Genetics"
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Sadka, Avi, Mikeal L. Roose e Yair Erner. Molecular Genetic Analysis of Citric Acid Accumulation in Citrus Fruit. United States Department of Agriculture, marzo 2001. http://dx.doi.org/10.32747/2001.7573071.bard.
Testo completoAbstract (sommario):
The acid content of the juice sac cells is a major determinant of maturity and fruit quality in citrus. Many citrus varieties accumulate acid in concentrations that exceed market desires, reducing grower income and consumer satisfaction. Pulp acidity is thought to be dependent on two mechanisms: the accumulation of citric acid in the vacuoles of the juice sac cells, and acidification of the vacuole. The major aim of the project was to direct effort toward understanding the mechanism of citric acid accumulation in the fruit. The following objectives were suggested: Measure the activity of enzymes likely to be involved in acid accumulation and follow their pattern of expression in developing fruit (Sadka, Erner). Identify and clone genes which are associated with high and low acid phenotypes and with elevated acid level (Roose, Sadka, Erner). Convert RAPD markers that map near a gene that causes low acid phenotype to specific co dominant markers (Roose). Use genetic co segregation to test whether specific gene products are responsible for low acid phenotype (Roose and Sadka). Objective 1 was fully achieved. Most of the enzymes of organic acid metabolism were cloned from lemon pulp. Their expression was studied during fruit development in low and high acid varieties. The activity and expression of citrate synthase, aconitase and NADP-isocitrate dehydrogenase (IDH) were studied in detail. The role that each enzyme plays in acid accumulation and decline was evaluated. As a result, a better understanding of the metabolic changes that contribute to acid accumulation was achieved. It was found that the activity of the mitochondrial aconitase is greatly reduced early in high-acid fruits, but not in acidless ones, suggesting that this enzyme plays an important role in acid accumulation. In addition, it was demonstrated that increases in the cytosolic forms of aconitase and NADP-IDH towards fruit maturation play probably a major role in acid decline. Our studies also demonstrated that the two mechanisms that contribute to fruit acidity, vacuolar acidification and citric acid accumulation, are independent, although they are tightly co-regulated. Additional, we demonstrated that sodium arsenite, which reduce fruit acidity, causes a transient inhibition in the activity of citrate synthase, but an induction in the gene expression. This part of the work has resulted in 4 papers. Objective 3 was also fully achieved. Using bulked segregant analysis, three random amplified polymorphic DNA (RAPD) markers were identified as linked to acitric, a gene controlling the acidless phenotype of pummelo 2240. One of them, which mapped 1.2 cM from acitric was converted into sequence characterized amplified region (SCAR marker, and into co dominant restriction length polymorphism (RFLP) marker. These markers were highly polymorphic among 59 citrus accessions, and therefore, they should be useful for selecting seedling progeny heterozygous for acitric in nearly all crosses between pummelo 2240 and other citrus genotypes. This part of the project resulted in one paper. Objective 4 was also fully achieved. Clones isolated by the Israeli group were sent to the American laboratory for co segregation analysis. However, none of them seemed to co segregate with the low acid phenotype. Both laboratories invested much effort in achieving the goals of Objective 2, namely the isolation of genes that are elevated in expression in low and high acid phenotypes, and in tissue cultures treated with arsenite (a treatment which reduces fruit acidity). However, conventional differential display and restriction fragment differential display analyses could not identify any differentially expressed genes. The isolation of such genes was the major aim of a continuation project, which was recently submitted.
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Dawson, William O., e Moshe Bar-Joseph. Creating an Ally from an Adversary: Genetic Manipulation of Citrus Tristeza. United States Department of Agriculture, gennaio 2004. http://dx.doi.org/10.32747/2004.7586540.bard.
Testo completoAbstract (sommario):
Citrus is one of the major agricultural crops common to Israel and the United States, important in terms of nutrition, foreign exchange, and employment. The economy of both citrus industries have been chronically plagued by diseases caused by Citrus tristeza virus (CTV). The short term solution until virus-resistant plants can be used is the use of mild strain cross-protection. We are custom designing "ideal" protecting viruses to immunize trees against severe isolates of CTV by purposely inoculating existing endangered trees and new plantings to be propagated as infected (protected) citrus budwood. We crossed the substantial technological hurdles necessary to accomplish this task which included developing an infectious cDNA clone which allows in vitro manipulation of the virus and methods to then infect citrus plants. We created a series of hybrids between decline-inducing and mild CTV strains, tested them in protoplasts, and are amplifying them to inoculate citrus trees for evaluation and mapping of disease determinants. We also extended this developed technology to begin engineering transient expression vectors based on CTV as tools for genetic improvement of tree crops, in this case citrus. Because of the long periods between genetic transformation and the ultimate assay of mature tree characteristics, there is a great need for an effective system that allows the expression or suppression of target genes in fruiting plants. Virus-based vectors will greatly expedite progress in citrus genetic improvement. We characterized several components of the virus that provides necessary information for designing virus-based vectors. We characterized the requirements of the 3 ’-nontranslated replication promoter and two 3 ’-ORF subgenomic (sg) mRNA controller elements. We discovered a novel type of 5’-terminal sgRNAs and characterized the cis-acting control element that also functions as a strong promoter of a 3 ’-sgRNA. We showed that the p23 gene controls negative-stranded RNA synthesis and expression of 3 ’ genes. We identified which genes are required for infection of plants, which are host range determinants, and which are not needed for plant infection. We continued the characterization of native dRNA populations and showed the presence of five different classes including class III dRNAs that consists of infectious and self-replicating molecules and class V dRNAs that contain all of the 3 ’ ORFs, along with class IV dRNAs that retain non-contiguous internal sequences. We have constructed and tested in protoplasts a series of expression vectors that will be described in this proposal.
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Dawson, William O., Moshe Bar-Joseph, Charles L. Niblett, Ron Gafny, Richard F. Lee e Munir Mawassi. Citrus Tristeza Virus: Molecular Approaches to Cross Protection. United States Department of Agriculture, gennaio 1994. http://dx.doi.org/10.32747/1994.7570551.bard.
Testo completoAbstract (sommario):
Citrus tristeza virus (CTV) has the largest genomes among RNA viruses of plants. The 19,296-nt CTV genome codes for eleven open reading frames (ORFs) and can produce at least 19 protein products ranging in size from 6 to 401 kDa. The complex biology of CTV results in an unusual composition of CTV-specific RNAs in infected plants which includes multiple defective RNAs and mixed infections. The complex structure of CTV populations poses special problems for diagnosis, strain differentiation, and studies of pathogenesis. A manipulatable genetic system with the full-length cDNA copy of the CTV genome has been created which allows direct studies of various aspects of the CTV biology and pathology. This genetic system is being used to identify determinants of the decline and stem-pitting disease syndromes, as well as determinants responsible for aphid transmission.
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Bar-Joseph, Moshe, William O. Dawson e Munir Mawassi. Role of Defective RNAs in Citrus Tristeza Virus Diseases. United States Department of Agriculture, settembre 2000. http://dx.doi.org/10.32747/2000.7575279.bard.
Testo completoAbstract (sommario):
This program focused on citrus tristeza virus (CTV), the largest and one of the most complex RNA-plant-viruses. The economic importance of this virus to the US and Israeli citrus industries, its uniqueness among RNA viruses and the possibility to tame the virus and eventually turn it into a useful tool for the protection and genetic improvement of citrus trees justify these continued efforts. Although the overall goal of this project was to study the role(s) of CTV associated defective (d)-RNAs in CTV-induced diseases, considerable research efforts had to be devoted to the engineering of the helper virus which provides the machinery to allow dRNA replication. Considerable progress was made through three main lines of complementary studies. For the first time, the generation of an engineered CTV genetic system that is capable of infecting citrus plants with in vitro modified virus was achieved. Considering that this RNA virus consists of a 20 kb genome, much larger than any other previously developed similar genetic system, completing this goal was an extremely difficult task that was accomplished by the effective collaboration and complementarity of both partners. Other full-length genomic CTV isolates were sequenced and populations examined, resulting in a new level of understanding of population complexities and dynamics in the US and Israel. In addition, this project has now considerably advanced our understanding and ability to manipulate dRNAs, a new class of genetic elements of closteroviruses, which were first found in the Israeli VT isolate and later shown to be omnipresent in CTV populations. We have characterized additional natural dRNAs and have shown that production of subgenomic mRNAs can be involved in the generation of dRNAs. We have molecularly cloned natural dRNAs and directly inoculated citrus plants with 35S-cDNA constructs and have shown that specific dRNAs are correlated with specific disease symptoms. Systems to examine dRNA replication in protoplasts were developed and the requirements for dRNA replication were defined. Several artificial dRNAs that replicate efficiently with a helper virus were created from infectious full-genomic cDNAs. Elements that allow the specific replication of dRNAs by heterologous helper viruses also were defined. The T36-derived dRNAs were replicated efficiently by a range of different wild CTV isolates and hybrid dRNAs with heterologous termini are efficiently replicated with T36 as helper. In addition we found: 1) All CTV genes except of the p6 gene product from the conserved signature block of the Closteroviridae are obligate for assembly, infectivity, and serial protoplast passage; 2) The p20 protein is a major component of the amorphous inclusion bodies of infected cells; and 3) Novel 5'-Co-terminal RNAs in CTV infected cells were characterized. These results have considerably advanced our basic understanding of the molecular biology of CTV and CTV-dRNAs and form the platform for the future manipulation of this complicated virus. As a result of these developments, the way is now open to turn constructs of this viral plant pathogen into new tools for protecting citrus against severe CTV terms and development of virus-based expression vectors for other citrus improvement needs. In conclusion, this research program has accomplished two main interconnected missions, the collection of basic information on the molecular and biological characteristics of the virus and its associated dRNAs toward development of management strategies against severe diseases caused by the virus and building of novel research tools to improve citrus varieties. Reaching these goals will allow us to advance this project to a new phase of turning the virus from a pathogen to an ally.
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Moore, Gloria A., Gozal Ben-Hayyim, Charles L. Guy e Doron Holland. Mapping Quantitative Trait Loci in the Woody Perennial Plant Genus Citrus. United States Department of Agriculture, maggio 1995. http://dx.doi.org/10.32747/1995.7570565.bard.
Testo completoAbstract (sommario):
As is true for all crops, production of Citrus fruit is limited by traits whose characteristics are the products of many genes (i.e. cold hardiness). In order to modify these traits by marker aided selection or molecular genetic techniques, it is first necessary to map the relevant genes. Mapping of quantitative trait loci (QTLs) in perennial plants has been extremely difficult, requiring large numbers of mature plants. Production of suitable mapping populations has been inhibited by aspects of reproductive biology (e.g. incompatibility, apomixis) and delayed by juvenility. New approaches promise to overcome some of these obstacles. The overall objective of this project was to determine whether QTLs for environmental stress tolerance could be effectively mapped in the perennial crop Citrus, using an extensive linkage map consisting of various types of molecular markers. Specific objectives were to: 1) Produce a highly saturated genetic linkage map of Citrus by continuing to place molecular markers of several types on the map. 2) Exploiting recently developed technology and already characterized parental types, determine whether QTLs governing cold acclimation can be mapped using very young seedling populations. 3) Determine whether the same strategy can be transferred to a different situation by mapping QTLs influencing Na+ and C1- exclusion (likely components of salinity tolerance) in the already characterized cross and in new alternative crosses. 4) Construct a YAC library of the citrus genome for future mapping and cloning.
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis e Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, ottobre 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
Testo completoAbstract (sommario):
One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.
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Guy, Charles, Gozal Ben-Hayyim, Gloria Moore, Doron Holland e Yuval Eshdat. Common Mechanisms of Response to the Stresses of High Salinity and Low Temperature and Genetic Mapping of Stress Tolerance Loci in Citrus. United States Department of Agriculture, maggio 1995. http://dx.doi.org/10.32747/1995.7613013.bard.
Testo completoAbstract (sommario):
The objectives that were outlined in our original proposal have largely been achieved or will be so by the end of the project in February 1995 with one exception; that of mapping cold tolerance loci based on the segregation of tolerance in the BC1 progeny population. Briefly, our goals were to 1) construct a densely populated linkage map of the citrus genome: 2) map loci important in cold and/or salt stress tolerance; and 3) characterize the expression of genes responsive to cold land salt stress. As can be seen by the preceding listing of accomplishments, our original objectives A and B have been realized, objective C has been partially tested, objective D has been completed, and work on objectives E and F will be completed by the end of 1995. Although we have yet to map any loci that contribute to an ability of citrus to maintain growth when irrigated with saline water, our very encouraging results from the 1993 experiment provides us with considerable hope that 1994's much more comprehensive and better controlled experiment will yield the desired results once the data has been fully analyzed. Part of our optimism derives from the findings that loci for growth are closely linked with loci associated with foliar Cl- and Na+ accumulation patterns under non-salinization conditions. In the 1994 experiment, if ion exclusion or sequestration traits are segregating in the population, the experimental design will permit their resolution. Our fortunes with respect to cold tolerance is another situation. In three attempts to quantitatively characterize cold tolerance as an LT50, the results have been too variable and the incremental differences between sensitive and tolerant too small to use for mapping. To adequately determine the LT50 requires many plants, many more than we have been able to generate in the time and space available by making cuttings from small greenhouse-grown stock plants. As it has turned out, with citrus, to prepare enough plants needed to be successful in this objective would have required extensive facilities for both growing and testing hardiness which simply were not available at University of Florida. The large populations necessary to overcome the variability we encountered was unanticipated and unforeseeable at the project's outset. In spite of the setbacks, this project, when it is finally complete will be exceedingly successful. Listing of Accomplishments During the funded interval we have accomplished the following objectives: Developed a reasonably high density linkage map for citrus - mapped the loci for two cold responsive genes that were cloned from Poncirus - mapped the loci for csa, the salt responsive gene for glutathione peroxidase, and ccr a circadian rhythm gene from citrus - identified loci that confer parental derived specific DNA methylation patterns in the Citrus X Poncirus cross - mapped 5 loci that determine shoot vigor - mapped 2 loci that influence leaf Na+ accumulation patterns under non-saline conditions in the BC1 population - mapped 3 loci that influence leaf Na+ accumulation paterns during salt sress - mapped 2 loci that control leaf Cl- accumulation patterns under non-saline conditions - mapped a locus that controls leaf Cl- accumulation patterns during salt stress Screened the BC1 population for growth reduction during salinization (controls and salinized), and cold tolerance - determined population variation for shoot/root ratio of Na+ and Cl- - determined levels for 12 inorganic nutrient elements in an effort to examine the influence of salinization on ion content with emphasis on foliar responses - collected data on ion distribution to reveal patterns of exclusion/sequestration/ accumulation - analyzed relationships between ion content and growth Characterization of gene expression in response to salt or cold stress - cloned the gene for the salt responsive protein csa, identified it as glutathione peroxidase, determined the potential target substrate from enzymatic studies - cloned two other genes responsive to salt stress, one for the citrus homologue of a Lea5, and the other for an "oleosin" like gene - cold regulated (cor) genes belonging to five hybridization classes were isolated from Poncirus, two belonged to the group 2 Lea superfamily of stress proteins, the others show no significant homology to other known sequences - the expression of csa during cold acclimation was examined, and the expression of some of the cor genes were examined in response to salt stress - the influence of salinization on cold tolerance has been examined with seedling populations - conducted protein blot studies for expression of cold stress proteins during salt stress and vice versa
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Eyal, Yoram, e Sheila McCormick. Molecular Mechanisms of Pollen-Pistil Interactions in Interspecific Crossing Barriers in the Tomato Family. United States Department of Agriculture, maggio 2000. http://dx.doi.org/10.32747/2000.7573076.bard.
Testo completoAbstract (sommario):
During the evolutionary process of speciation in plants, naturally occurring barriers to reproduction have developed that affect the transfer of genes within and between related species. These barriers can occur at several different levels beginning with pollination-barriers and ending with hybrid-breakdown. The interaction between pollen and pistils presents one of the major barriers to intra- and inter-specific crosses and is the focus of this research project. Our long-term goal in this research proposal was defined to resolve questions on recognition and communication during pollen-pistil interactions in the extended tomato family. In this context, this work was initiated and planned to study the potential involvement of tomato pollen-specific receptor-like kinases (RLK's) in the interaction between pollen and pistils. By special permission from BARD the objectives of this research were extended to include studies on pollen-pistil interactions and pollination barriers in horticultural crops with an emphasis on citrus. Functional characterization of 2 pollen-specific RLK's from tomato was carried out. The data shows that both encode functional kinases that were active as recombinant proteins. One of the kinases was shown to accumulate mainly after pollen germination and to be phosphorylated in-vitro in pollen membranes as well as in-vivo. The presence of style extract resulted in dephosphorylation of the RLK, although no species specificity was observed. This data implies a role for at least one RLK in pollination events following pollen germination. However, a transgenic plant analysis of the RLK's comprising overexpression, dominant-negative and anti-sense constructs failed to provide answers on their role in pollination. While genetic effects on some of the plants were observed in both the Israeli and American labs, no clear functional answers were obtained. An alternative approach to addressing function was pursued by screening for an artificial ligand for the receptor domain using a peptide phage display library. An enriched peptide sequence was obtained and will be used to design a peptide-ligand to be tested for its effect o pollen germination and tube growth. Self-incompatibility (SI) in citrus was studied on 3 varieties of pummelo. SI was observed using fluorescence microscopy in each of the 3 varieties and compatibility relations between varieties was determined. An initial screen for an S-RNase SI mechanism yielded only a cDNA homologous to the group of S-like RNases, suggesting that SI results from an as yet unknown mechanism. 2D gel electrophoresis was applied to compare pollen and style profiles of different compatibility groups. A "polymorphic" protein band from style extracts was observed, isolated and micro-sequenced. Degenerate primers designed based on the peptide sequence date will be used to isolate the relevant genes i order to study their potential involvement in SI. A study on SI in the apple cultivar Top red was initiated. SI was found, as previously shown, to be complete thus requiring a compatible pollinator variety. A new S-RNase allele was discovered fro Top red styles and was found to be highly homologous to pear S-RNases, suggesting that evolution of these genes pre-dated speciation into apples and pears but not to other Rosaceae species. The new allele provides molecular-genetic tools to determine potential pollinators for the variety Top red as well as a tool to break-down SI in this important variety.