Transcriptome Sequencing of Chickpea (Cicer arietinum L.) Genotypes for Identification of Drought-Responsive Genes Under Drought Stress Condition

Chickpea (Cicer arietinum L.) is a pulse crop valued for its high protein content, grown in semi-arid tropics and Mediterranean regions. Its yield remains affected by biotic and abiotic stresses with drought alone being responsible for up to 50% annual loss of yield. Transcriptome analysis of a sensitive and a tolerant cultivar of chickpea has been done earlier to unravel the molecular basis for drought and salinity stress responses. In the present study, we performed transcriptome analysis of two drought-tolerant genotypes, BG-362 and P-256, under polyethylene glycol-simulated drought stress to decipher the genes and pathways that are commonly regulated in these genotypes. RNA-Seq using Illumina platform generated 152 million high-quality reads. Reference-guided assembly of genome yielded a total of 37,943 transcripts representing 22,701 genes. Among the 1624 genes that were observed to be differentially expressed under drought, 97 genes were common in both the genotypes. These included the upregulated genes, such as probable mannitol dehydrogenase, serine hydroxymethyltransferase 4-like, 17.5 kDa class I heat shock protein-like, cytochrome P450 81E8-like, and galactinol-sucrose galactosyltransferase-like, and downregulated genes, such as probable xyloglucan endotransglucosylase/hydrolase protein 23, abscisic acid 8′-hydroxylase 1-like, Calmodulin-like protein 11, and proline dehydrogenase 2 mitochondrial-like genes. A major finding was the involvement of transcription factors, including AP2-EREBP, bHLH, bZIP, C3H, MYB, NAC, WRKY, and MADS. The present study is the first comparative analysis of RNA-Seq data for two drought-tolerant chickpea genotypes. These findings would help in improving drought tolerance across chickpea genotypes.