Expression comparisons of defense-related genes in resistant and susceptible chickpea cultivars in response to Ascochyta rabiei

Abstract

Ascochyta blight caused by Ascochyta rabiei is a destructive disease affecting chickpea crops worldwide. Numerous studies have sought to identify resistance genes involved in the defense response against Ascochyta blight, but the function of potential resistant genes across different chickpea genetic backgrounds remains poorly understood. This study evaluated the potential role of 16 genes involved in defense responses in partially resistant (ILC482) and susceptible (Sari98) chickpea cultivars. The leaf samples were collected from 2-week-old seedlings at 6, 12, 24, 48, and 72 h post-inoculation (hpi) with A. rabiei and analyzed for differential expression of defense genes using qRT-PCR. Twelve out of 16 genes were differentially regulated between chickpea cultivars. The qRT-PCR analysis indicated that the expression of defense genes was significantly higher in the partially resistant cultivar than that in the susceptible cultivar. The time point of the highest upregulation ratio for defense genes was variable between the cultivars. The expression of glutathione S-transferase, serine/threonine-protein kinase, WRKY gene (CaWRKY16), and wall associated-receptor kinase genes reached maximum levels in the resistant cultivar at 6 hpi, while antimicrobial peptide precursor (SNAKIN2), polymorphic antigen membrane protein, ethylene receptor-like sequences (CaETR1), and two nucleotide-binding site-leucine-rich repeat genes showed the highest activity at 24 hpi. In particular, CaWRKY16, CaWRKY50, glutathione S-transferase, CaETR1, and wall-associated-receptor kinase genes provided valuable information for assessing chickpea cultivars with different resistance levels. The results indicated that the expression changes of these genes involved in defense pathways play a crucial role in enhanced resistance of chickpea plants against Ascochyta blight and, therefore could be potential candidate genes for future breeding studies.