Molecular analysis indicates the involvement of Jasmonic acid biosynthesis pathway in low-potassium (K+) stress response and development in chickpea (Cicer arietinum)

Abstract

K + is a major macronutrient and its deficiency hampers plant growth and yield. Plants combat low-K + stress by modifying their root system architecture (RSA). Here, morphophysiological analysis revealed that chickpea plants exhibit sensitivity to low-K + stress as shown by impaired primary root growth. Phytohormone JA regulates various facets of plant root growth, however, information of JA biosynthesis genes in chickpea is missing. We performed genome-wide identification and molecular characterization of JA biosynthesis pathway genes in chickpea. Total 33 genes belonging to different families i.e., LOX s-18, AOS s-3, AOC s-2, OPR s-6 and JAR s-4 were identified in the chickpea genome. In-planta analysis revealed the localization of CaLOX7, − 10, CaAOS1, − 2 and CaAOC1 at subcellular compartments, such as membrane, chloroplast and cytoplasm. Protein expression and in-vitro enzymatic activity analysis showed that CaAOS1 an CaOPR2 are the functional enzymes in chickpea. Promoters of most genes harboured abiotic stress, hormone and development related cis -regulatory elements, suggesting their role in nutrient deficiency, abiotic stress and plant development. qRT-PCR expression profiling showed that about 15 JA biosynthesis genes from different families express differentially whereas, JA catabolism genes were repressed in chickpea root and shoot under low-K + stress. In addition, JA biosynthesis genes showed differential expression in vegetative and reproductive development, senescence stages, desiccation, salinity and cold stress. These findings indicate the involvement of JA biosynthesis pathway in low-K + stress response and development in chickpea. Low-K + stress and development related genes identified in this study could be utilized in genetic engineering of chickpea plants for improved traits. • 33 JA biosynthesis pathway genes (18 LOXs, 3 AOSs, 2AOCs, 6 OPRs and 4 JARs) are identified in the chickpea genome. • They were localized at sub-cellular compartments such as, chloroplast, plasma membrane, cytoplasm and nucleus. • Enzymatic activity assay revealed that CaAOS1 and CaOPR2 are the functional enzymes. • Several genes from different families were differentially expressed under K + deficiency in chickpea. • Expression analysis indicate their overlapping function in low-K + stress, abiotic stresses, and plant development.