Molecular Cloning and Expression Study of Resistant Gene Analogues Rgas In Coconut

Abstract

Coconut (Cocos nucifera L.) is an important and versatile plantation crop. It has newlineglobal significance for both agriculture and industries due to its multifarious uses. The newlinepalm is highly susceptible to a variety of diseases leading to decline in yield and quality. newlineEnhancing the plant disease resistance has been the prime goal of coconut breeding newlineprograms around the world. Plant nucleotide-binding-site (NBS)- leucine-rich-repeat newline(LRR), receptor-like proteins (RLP) and receptor like protein kinase (RLK) gene superfamilies newlineare effective for mounting plant defense responses against a wide range of newlinepathogens. Therefore, identification of such R-Gene Analogues (RGAs) provides a vital newlinefoundation for improving disease resistance in plants. Transcriptomic approach is newlineimperative for deciphering the plant-pathogen interaction pathways and RGAs discovery newlinein coconut, given the scarce genomic resources available. In this study, RNA-seq was newlineused to generate the transcriptome of leaf samples of coconut root (wilt) disease-resistant newlinecultivar Chowghat Green Dwarf. A total of 235 RGA sequences, comprising three gene newlinefamilies with 10 distinguishable classes of RGAs; NBS-LRR (CNL, TN, TX, N, CN, TMCC newlineor NL), RLK (LRR-RLK and LecRLK) and STK, were successfully identified through newlinecomprehensive bioinformatics analysis. Domain and conserved motif predictions of newlineobtained RGAs were performed to analyze the architectural diversity. Multiple sequence newlinealignment and phylogenetic analysis of the deduced amino acid sequences revealed the newlineevolutionary relationship among RGAs. Non-synonymous to synonymous nucleotide newlinesubstitution (Ka:Ks) ratios for these NBS-type RGAs and RLK-type RGAs were less newlinethan 1, indicating that purifying or negative selection played an important role in the newlineRGA evolutionary process in coconut.Transcripts, sequenced by next generation sequencing (NGS) techniques, are newlinemostly incomplete in length, especially towards the ends of genes, while complete genome newlinesequencing has only been conducted in very few species due to the compl