Cloning, characterization and expression analysis of NBS-LRR-type resistance gene analogues (RGAs) in coconut

Coconut palms are highly susceptible to diseases caused by different pathogens, and replanting with resistant varieties is the best way to manage them. Obtaining a collection of resistance gene analogues (RGAs) is an effective strategy to identify genomic regions linked to disease resistance. We have successfully used a comparative genomics approach to amplify putative RGAs from the coconut root (wilt) disease resistant cultivar Chowghat Green Dwarf (CGD) by using primers designed based on conserved motifs of the NBS-LRR domain of the date palm. The amplified sequences were cloned, sequenced and characterized. The coconut RGAs had high identity to monocot NBS-LRRs. A complete structural analysis and 3-D modeling of the NBS domain of coconut RGA was also undertaken. Real-time quantitative polymerase chain reaction analysis indicated that the isolated coconut NBS-LRR class RGAs was expressed more in root (wilt) disease resistant genotypes than in susceptible ones. This study would provide a base for future efforts to map disease resistant traits in coconut

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Not AvailableA comparative study of gene expression patterns during different stages of in vitro regeneration in two coconut cultivars viz. WCT (West Coast Tall) and COD (Chowghat Orange Dwarf) was carried out in this study. Calli were obtained from shoot meristem explants and expression patterns of eight genes at different development stages in the two cultivars were analyzed using RT-qPCR. The results revealed the enhanced expression of PKL, SERK and WUS in embryogenic calli compared to non-embryogenic calli. High expression of GLP, ECP and GST could be observed in normal somatic embryos compared to abnormal somatic embryos. Enhanced expression of ECP, LEAFY, GLP and WRKY could be observed in normal meristemoids compared to aberrant meristemoids. When the two cultivars were compared, higher somatic embryogenesis was noticed in WCT as compared to COD. Embryogenic calli of WCT showed higher expression of SERK, PKL and WUS compared to COD. Somatic embryos of WCT showed high expression of GLP and GST compared to COD, where as for ECP gene, higher expression was observed in WCT compared to COD. In cases of WRKY and LEC, higher levels of expression were observed in WCT meristemoids when compared to COD. The results revealed signifi cant differences in regeneration potential and gene expression patterns in the two coconut cultivars suggesting genotypic differences of cultivars to in vitro culture.Not Availabl

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Not AvailableCoconut palms are highly susceptible to diseases caused by different pathogens, and replanting with resistant varieties is the best way to manage them. Obtaining a collection of resistance gene analogues (RGAs) is an effective strategy to identify genomic regions linked to disease resistance. We have successfully used a comparative genomics approach to amplify putative RGAs from the coconut root (wilt) disease resistant cultivar Chowghat Green Dwarf (CGD) by using primers designed based on conserved motifs of the NBS-LRR domain of the date palm. The amplifi ed sequences were cloned, sequenced and characterized. The coconut RGAs had high identity to monocot NBS-LRRs. A complete structural analysis and 3-D modeling of the NBS domain of coconut RGA was also undertaken. Real-time quantitative polymerase chain reaction analysis indicated that the isolated coconut NBS-LRR class RGAs was expressed more in root (wilt) disease resistant genotypes than in susceptible ones. This study would provide a base for future efforts to map disease resistant traits in coconut.Not Availabl