Drought priming triggers diverse metabolic adjustments and induces chilling tolerance in chickpea (Cicer arietinum L.)

Abstract

Chickpea (Cicer arietinum L.) suffers from chilling stress at the reproductive stage (<15 °C) which leads to significant yield loss. This study presents a comprehensive plant response to drought priming and its effect on chilling tolerance during the reproductive stage in two chickpea cultivars PBG1 and PBG5. Lipidome profiling (Fatty acid methyl esters analysis), metabolome profiling (GC-MS based untargeted analysis), fatty acid desaturases and antioxidative gene expression (qRT-PCR) were analyzed to monitor physiological and biochemical events after priming during flowering, podding and seed filling stages. Drought priming alleviated membrane damage and chlorophyll degradation by increasing membrane unsaturated fatty acids (18:3) along with up-regulation of various fatty acid desaturases (CaFADs) genes and antioxidative machinery during flowering and improved seed yield in PBG5. PCA, HCA, and KEGG pathway analysis of 87 identified metabolites showed that metabolites were regulated differently in both cultivars under non-primed and primed conditions. The plant response was more apparent at flowering and podding stages which coincided with chilling temperature (<15 °C). Drought priming stimulated many important genes, especially FADs, antioxidative proteins and accumulation of key metabolites (proline and TCA intermediates) required for defense especially in PBG5. This explains that plant's response to drought priming not only depends on developmental stage, and temperature regime (<15 °C) but also on the genotypic-specificity.