Genome wide in-silico analysis of NPR1 gene family in Citrus reticulata and its comparison with Arabidopsis

Abstract: Nonexpresser of pathogenesis-related proteins 1 (NPR1), and its paralogue are important salicylic acid (SA) receptors that play important roles in plant defense. NPR gene family analysis has not yet been conducted in C. reticulata. The CrNPR1-like and AtNPR1-like protein sequences were retrieved from online genome databases and were subjected to various bioinformatics tools. This study presents the first genome-wide identification of NPR1 gene in C. reticulata, resulting in 7 family members. Phylogenetic analysis of 7 CrNPR1-like proteins, along with NPR1-related proteins from 15 species revealed that the proteins were grouped into three major clades. The CrNPR1-like genes in the same Arabidopsis subfamilies had similar protein domain compositions, number of exons and conserved motifs. All 7 CrNPR genes were segmented duplicated, and no tandem duplicate was observed. Transcriptome data revealed note-worthy expression in leaf, fruit and rind patterns of CrNPR1-like genes. Nearly six out of seven CrNPR, expressed in leaf infected with Xylella fastidiosa, indicates that these tissues and organs contribute to improved defense response against pathogens. These results pave the way for more functional characterization of NPR1s in C. reticulate and related species.