Browsing by Author "Lebrun, P."
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Item An analysis of genetic diversity in coconut ( Cocos nucifera ) populations from across the geographic range using sequence-tagged microsatellites (SSRs) and AFLPs(2000) Teulat, B.; Aldam, C.; Trehin, R.; Lebrun, P.; Barker, J.H.A.; Arnold, G.M.; Karp, A.; Baudouin, L.; Rognon, F.Item An analysis of genetic diversity in coconut (Cocos nucifera) populations from across the geographic range using sequence-tagged microsatellites (SSRs) and AFLPs(2000) Teulat, B.; Aldam, C.; Trehin, R.; Lebrun, P.; Barker, J.H.A.; Arnold, G.M.; Karp, A.; Baudouin, L.Item Genetic diversity in coconut (Cocos nucifera L.) revealed by restriction fragment length polymorphism (RFLP) markers(1998) Lebrun, P.; N' cho, Y.P.; Seguin, M.; Grivet, L.; Baudouin, L.A study of the genetic diversity in coconut by RFLP analysis was performed in 100 individuals representing 10 Tall and seven Dwarf local populations or ‘ecotypes’ from various geographical origins. Nine cDNA clones from rice, one mitochondrial DNA clone (CoxI) and one genomic clone (rDNA) from wheat were used as probe for southern hybridization. The distribution of the 40 polymorphic bands revealed by rice cDNA clones was studied using a multivariate analysis and allowed to identify two main genetical groups. The first one includes the ecotypes from the Far East and from the South Pacific, whereas the other one comprises the ecotypes from India, Sri Lanka and Western Africa. The rDNA and the CoxI probes confirm this distinction. The Far East and the Pacific regions which were the most likely center of origin also exhibit the widest polymorphism. The associations between the Panama Tall and the Pacific group and between theWest African Tall and the Indian Ocean group reflect their likely origin. The Comoro Tall appears to be intermediate between the two main groups, and could reflect the old migration route between Indonesia and Madagascar. All Dwarf varieties belong to the first group, even those collected in West Africa. Those were probably introduced fromAsia and Pacific at the beginning of the century. The crosspollinating Tall ecotypes were generally more polymorphic than the self pollinating Dwarf ecotypes. The legitimacy of two hybrids between ecotypes was confirmed and maternal inheritance of mitochondrial genome was observed.Item Genetic survey of 10 Indian coconut landraces by simple sequence repeats (SSRs)(Elsevier, 2008) Rajesh, M.K.; Arunachalam, V.; Nagarajan, P.; Lebrun, P.; Samsudeen, K.; Thamban, C.A rich genetic diversity of coconut exists in farmer’s fields, which represent valuable genetic resource for breeding. The study was conducted to assess the pattern of diversity in 102 coconut palms representing 10 landraces from 3 coconut-growing communities of India using 14 simple sequence repeat (SSR) markers. A total of 90 alleles were detected with an average of 6.42 alleles per locus and an average polymorphism information content of 0.61. Expected heterozygosity (He) was highest for the two tall landraces from Pallikkara community, while the least heterozygosity was observed for the dwarf coconut landraces from Vayalar community. Mean fixation index (FST) of 0.42 indicates a high level of population differentiation. A low gene flow (Nm) of 0.37 was observed. Based on molecular data, genetic similarities were calculated. The unweighted pair group method with arithmetic averages (UPGMA) cluster analysis grouped the landraces according to their geographical locations and breeding behaviour. The practical implications of this study in farmer participatory evaluation and conservation of coconut genetic resources are highlighted.Item Identification of molecular markers associated with mite resistance in coconut (Cocos nucifera L.)(2007) Shalini, K.V.; Manjunatha, S.; Lebrun, P.; Berger, A.; Baudouin, L.; Pirany, N.; Ranganath, R.M.; Theertha Prasad, D.Item Identification of molecular markers associated with mite resistance in coconut (Cocos nucifera L.)(2007) Shalini, K.V.; Manjunatha, S.; Lebrun, P.; Berger, A.; Baudouin, L.; Ranganath, R.M.; Pirany, N.; Theertha Prasad, D.Coconut mite (Aceria guerreronis‘Keifer’) has become a major threat to Indian coconut (Coc¸cos nuciferaL.) cultivators and the processing industry. Chemical and biological control measures have proved to be costly, ineffective, and ecologically undesirable. Planting mite-resistant coconut cultivars is the most effective method of preventing yield loss and should form a major component of any integrated pest management stratagem. Coconut genotypes, and mite-resistant and -susceptible accessions were collected from different parts of South India. Thirty-two simple sequence repeat (SSR) and 7 RAPD primers were used for molecular analyses. In single-marker analysis, 9 SSR and 4 RAPD markers associated with mite resistance were identified. In stepwise multiple regression analysis of SSRs, a combination of 6 markers showed 100% association with mite infestation. Stepwise multiple regression analysis for RAPD data revealed that a combination of 3 markers accounted for 83.86% of mite resistance in the selected materials. Combined stepwise multiple regression analysis of RAPD and SSR data showed that a combination of 5 markers explained 100% of the association with mite resistance in coconut. Markers associated with mite resistance are important in coconut breeding programs and will facilitate the selection of mite-resistant plants at an early stage as well as mother plants for breeding programs.Item Qtl Analysis of Fruit Components in the Progeny of a Rennell Island Tall Coconut (cocos Nucifera L. ) Individual(Springer-Verlag, 2006-01) Baudouin, L.; Lebrun, P.; Konan, J.L.; Ritter, E.; Berger, A.; Billotte, N.We Investigated the Genetic Factors Controlling Fruit Components in Coconut by Performing Qtl Analyses for Fruit Component Weights and Ratios in a Segregating Progeny of a Rennell Island Tall Genotype. The Underlying Linkage Map of This Population was already Established in a Previous Study, as well as Qtl Analyses for Fruit Production, which were Used to Complement our Results. The Addition of 53 New Markers (mainly SSRs) Led to Minor Amendments in the Map. A Total of 52 Putative QTLs were Identified for the 11 Traits under Study. Thirty-four of them were Grouped in Six Small Clusters, which Probably Correspond to Single Pleiotropic Genes. Some Additional QTLs Located Apart from these Clusters also had Relatively Large Effects on the Individual Traits. The QTLs for Fruit Component Weight, Endosperm Humidity and Fruit Production were Found at Different Locations in the Genome, Suggesting that Efficient marker-assisted Selection for Yield can be Achieved by Selecting QTLs for the Individual Components. The Detected QTLs Descend from a Genotype Belonging to the "pacific" Coconut Group. Based on the Known Molecular and Phenotypic Differences between "pacific" and "Indo-Atlantic" Coconuts, we Suggest that a Large Fraction of Coconut Genetic Diversity is still to be Investigated by Studying Populations Derived from Crosses between these Groups.Item Recent lethal yellowing outbreak: why is the Malayan Yellow Dwarf Coconut no longer resistant in Jamaica?(Springer-Verlag, 2008) Lebrun, P.; Baudouin, L.; Myrie, W.; Berger, A.; Dollet, M.In Jamaica, the Maypan, a hybrid of Malayan Yellow Dwarf (MYD) and Panama Tall coconut, previously considered highly resistant, is currently being devastated by an epidemic outbreak of lethal yellowing disease. There are several possible causes for this change. In this study, we checked that affected planting material in Jamaica is genetically the same as the material shown to be resistant. We compared the deoxyribonucleic acid (DNA) of MYD sampled in four locations in Jamaica with a reference DNA of the same cultivar collected in five different countries. The results of our analyses showed more variation at 34 simple sequence repeat loci in Jamaica than in the rest of the world providing clear evidence for the presence of about 16% of alleles that do not match the usual typical MYD genotype. These alleles appear to have already been present in the introduced germplasm. This rules out a possible cause of the new outbreak: The observed heterogeneity may have caused some loss of resistance but is insufficient to explain a massive outbreak of the diseaseItem Recent lethal yellowing outbreak: why is the Malayan Yellow Dwarf Coconut no longer resistant in Jamaica?(2008) Berger, A.; Myrie, W.; Baudouin, L.; Lebrun, P.; Dollet, M.In Jamaica, the Maypan, a hybrid of Malayan Yellow Dwarf (MYD) and Panama Tall coconut, previously considered highly resistant, is currently being devastated by an epidemic outbreak of lethal yellowing disease. There are several possible causes for this change. In this study, we checked that affected planting material in Jamaica is genetically the same as the material shown to be resistant. We compared the deoxyribonucleic acid (DNA) of MYD sampled in four locations in Jamaica with a reference DNA of the same cultivar collected in five different countries. The results of our analyses showed more variation at 34 simple sequence repeat loci in Jamaica than in the rest of the world providing clear evidence for the presence of about 16% of alleles that do not match the usual typical MYD genotype. These alleles appear to have already been present in the introduced germplasm. This rules out a possible cause of the new outbreak: The observed heterogeneity may have caused some loss of resistance but is insufficient to explain a massive outbreak of the disease.