Alterations in starch, sucrose, and abscisic acid metabolism under drought stress in contrasting genotypes of chickpea.

Plants respond to water scarcity by modifying transcription and metabolite accumulation; however, mechanisms leading to drought tolerance/sensitivity in chickpea (Cicer arietinum L.) are poorly understood. To understand the molecular basis of drought tolerance/sensitivity, the carbohydrate content and transcriptional changes in the genes of sugar, starch, abscisic acid (ABA), and gibberellic acid pathways were studied in a drought-tolerant genotype (ICC 8950) and a drought-sensitive genotype (ICC 3776). Droughts disrupted carbohydrate metabolism in ICC 3776, leading to decrease in starch content and increase in sugar content, including sucrose. In ICC 8950, under drought stress, the starch content remained unchanged but sugar levels increased slightly. The reduction in starch content in ICC 3776 resulted from increased degradation rather than decreased synthesis, whereas in ICC 8950, starch anabolism as well as catabolism genes were downregulated, leading to unchanged starch levels. The increase in sucrose content in ICC 3776 under drought stress resulted from lower degradation due to the downregulation of cell wall invertase. The expression of ABA catabolism genes under drought increased in ICC 3776 but decreased in ICC 8950, suggesting increased ABA content in ICC 3776 but not in ICC 8950. This study showed that drought causes a decrease in the starch content and an increase in the sucrose and ABA contents in the drought-sensitive genotype, whereas the drought-tolerant genotype maintains starch and sucrose levels coupled with lower ABA.