Uplc-Hrms Based Non-Targeted Metabolomic Profiling in Chickpea Reveals Complex Mechanisms Involved in Drought Tolerance Induced By PGR and PGPR.

Plant growth regulator (PGR) and plant growth promoting Rhizobacteria (PGPR) can be utilized to improve productivity of plants under drought conditions. However, little is known about the impact of PGR and PGPR on metabolic regulation in chickpea under drought conditions. The present study was carried out to investigate the metabolic profiling of leaves in chickpea exposed to drought stress and treated with consortium of PGR and PGPR. Ultrahigh performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) analyses was carried out to identify metabolites showing differential level of changes in chickpea varieties under drought condition. The two chickpea varieties, drought tolerant (93127) and sensitive (Punjab Noor-2009), were soaked with PGPR isolates for 2-3 h prior to sowing. The salicylic acid and putrescine were sprayed on 20 days old seedlings. Plants were exposed to drought stress at three leaves stage. The leaves from well-watered, water-deficit, and PGPR and PGR treated plants were collected at 14 days and 25 days after the induction of water stress for metabolic profiling. ANOVA and heat map identified levels of 20 metabolites significantly changed under drought condition over control, while 25 metabolites demonstrated significantly altered level due to PGR and PGPR consortium treatment over drought condition by PLS-DA VIP scoring. Proline, L-arginine, L-histidine, L-isoleucine and tryptophan were accumulated in the leaves of chickpea exposed to drought stress. Choline, phenylalanine, GABA and alpha ketoglutaric acid showed decreased level under drought. PGPR and PGR treatment induced significant accumulation of riboflavin, L-asparagine, aspartate, glycerol, nicotinamide, and 3-hydroxy-3-methyglutarate in leaves of chickpea. Increased level of Isoleucine, allantoin and guanine was recorded in tolerant variety under drought condition. PGPR and PGR treatment changed the amino acid content in plants which might lead to an improved tolerance even in drought sensitive variety as compared to untreated drought tolerant variety grown under water deficit condition.