Altering climatic conditions and water stress drastically affects the chilli crop yield. In this scenario we adapted a strategic approach for screening of elite chilli genotypes, by exploring role of seed antioxidants in stress tolerance during vegetative phase. A total of 20 chilli genotypes' seed antioxidant potential and its effect on water stress tolerance were studied at three water regimes, namely, control (100% Field Capacity), moderate (80% Field Capacity), and severe (60% Field Capacity) stress conditions. Drought tolerance traits relative water content, chlorophyll content, and activities of superoxide dismutase and catalase enzymes were measured. A strong correlation was observed between seed antioxidants and water stress tolerant traits in seedlings. Genotypes KCa-5, KCa-6, and KCa-10 showed low quantity of H2O2 and Malondialdehyde in seeds and maintained high membrane integrity and chlorophyll content in seedlings. High content of proline in KCa-5, KCa-7, and KCa-10 seeds retained high relative water content at seedling stage under severe water stress. Present work reveals genotypic differences of hot pepper to different water regimes. Based on Principal Component Analysis (PCA) of seed antioxidant variables and drought tolerance indices twenty genotypes segregated into three clusters, namely, drought tolerant and susceptible and moderately tolerant.

Drought is one of the predominant abiotic stresses which have phenomenal impact on crop productivity. Alterations in aquaporin gene expressions are part of complex molecular responses by plant in response to drought. To better understand the role of aquaporins in economically important crop chilli (Capsicum annuum), drought induced gene expression of twelve aquaporins was determined in drought tolerant-KCa-4884 and drought susceptible-G-4 genotypes. Conjointly, the effect of drought on leaf water status and photosynthetic parameters were evaluated. Gene expression of all examined 12 aquaporins was up-regulated in KCa-4884 and in contrast, all the aquaporin genes were down-regulated in G-4 under drought stress. Significant variations among two chilli genotypes have been recorded in photosynthetic rate (P n), stomatal conductance (G s), and relative water content (RWC), sub-stomatal CO 2 concentration (C i). KCa-4884 revealed significantly high rates of P n and RWC and decreased G s under water deficit conditions providing evidence for superior drought adaptive strategies. Differences in physiological parameters illustrate prevention of water loss during drought. Up-regulation of aquaporins in drought tolerant genotype implicates their possible role in water relations and photosynthetic performance even under extended drought conditions.

Drought is one of the major environmental constrains that limit plant performance worldwide. Plant apoplast which acts as connecting link between environment and plant protoplast carries multiple functions in plant metabolism and signalling. To investigate the drought induced changes in apoplast, proteome analysis in conjunction with antioxidant enzyme activity changes were studied in chilli (Capsicum annuum L). Drought induced apoplast proteome revealed augmented phenyl alanine ammonia lyase, peroxidase activities and reduced catalase activity. LC-MS analysis of apoplast proteome revealed differential expression of proteins under water stress conditions. Up-regulation of 43 protein species which encompass stress related proteins such as defensins, peroxidises, polygalaturonase inhibitor proteins, superoxide dismutase proteins were observed. Unlike control, twenty unique protein species were identified to be present in proteome of drought treated plants. Qualitative and quantitative changes in apoplast proteome emphasize the dynamics of plant apoplast and its role in drought stress. This work would provide insights into drought induced proteomic changes in apoplast and also would prove to be useful for protein phenotyping.