Comparative physiology and proteomic analysis of two wheat genotypes contrasting in drought tolerance.

Comparative physiology and proteomic analyses were conducted to monitor the stress response of two wheat genotypes (SERI M 82 (SE) and SW89.5193/kAu2 (SW)) with contrasting responses to drought stress. Under stress condition, the tolerant genotype (SE) produced higher shoot and root biomasses, longer roots and accumulated higher level of ABA in leaves. Physiological measurements suggested that the SE genotype was more efficient in water absorption and could preserve more water presumably by controlling stomata closure. Proteomic analysis showed an increased abundance of proteins related to defense and oxidative stress responses such as GLPs, GST, and SOD, and those related to protein processing such as small HSPs in roots of both genotypes in response to drought stress. Interestingly, the abundance of proteins such as endo-1,3-beta-glucosidase, peroxidase, SAMS, and MDH significantly increased in roots or leaves of the SE genotype and decreased in that of the SW one. In addition, an increased abundance of APX was detected in leaves and roots of the SE genotype and a decreased abundance of 14-3-3 and ribosomal proteins were noted in the SW one in response to drought stress. Our findings led to a better understanding about the integrated physiology and proteome responses of wheat genotypes with nearly contrasting responses to drought stress. BIOLOGICAL SIGNIFICANCE: We applied a comparative physiology and proteomic analysis to decipher the differential responses of two contrasting wheat genotypes to drought stress. Based on physiological measurements the tolerant genotype (SE) showed better drought response by developing deep root system, higher root and shoot biomasses, and higher level of ABA in leaves. Proteomic analysis showed an increased abundance of proteins related to defense and oxidative stress responses such as GLPs, GST, and SOD, and those related to protein processing such as small HSPs in roots of both genotypes in response to drought stress. In addition, the abundance of proteins such as glucan endo-1,3-beta-glucosidase, peroxidases, SAMS, and MDH increased in roots or leaves of the tolerant genotype (SE) and decreased in that of the sensitive genotype (SW). Overall, proteins related to oxidative stress, protein processing and photosynthesis showed decreased abundance to a greater extent in the sensitive genotype (SW).