Transcriptome-wide identification and characterization of resistant gene analogs (RGAs) of ginger (Zingiber officinale Rosc.) and mango ginger (Curcuma amada Roxb.) under stress induced by pathogen

Resistance genes (R-genes) are responsible for activation of plant defense signaling involving the recognition of pathogen effectors by R-proteins resulting in the onset of the hypersensitive response (HR). R-gene analogs (RGAs) have been characterized in numerous plants and efficiently used for plant breeding purposes. Ginger (Zingiber officinale Rosc.) is an asexual spice crop which is affected by many diseases of which bacterial wilt caused by Ralstonia solanacearum is one of the most important production constraints. Out of the Zingiberaceous species screened for bacterial wilt resistance, mango ginger (Curcuma amada Roxb.) was found to be resistant. With an aim to study the disease resistance mechanism in mango ginger, RGAs have been identified from the ginger transcriptome database (gTDB) and characterized. Screening for the RGAs using bioinformatics-driven methods resulted in the identification of 160 clusters in mango ginger and 212 clusters in ginger with similarity to known R-genes that were classified based on the presence and organization of conserved domains. A large number of the clusters with gene ontology related to disease resistance were identified to be of NBS-LRR type. The gene expression studies of selected NBS-LRR transcripts identified that they got highly expressed in mango ginger in the initial hours post inoculation indicating their possible role in disease resistance. The study paves a way to understand the existing RGAs in ginger and mango ginger. Unfolding the mechanism that confers the high level of resistance in mango ginger may provide new insights for developing bacterial wilt resistance in ginger.