Comparative physiological, ultrastructural and proteomic analyses reveal sexual differences in the responses of Populus cathayana under drought stress.

Drought is a major abiotic stress, limiting the survival and growth of young plants. However, little is known about sex-dependent responses to drought at the proteome level. In this study, we carried out investigations on comparative proteomics, combined with physiological and organelle structure analyses, in males and females of Populus cathayana Rehd. Three-month-old poplar cuttings were treated at 30% of field capacity and at 100% field capacity as a control in a greenhouse for 40 days. Drought greatly inhibited plant growth, damaged the photosynthetic system and destructed the structures of chloroplasts, mitochondria and cellular membranes. However, males suffered less from the adverse effects of drought than did females. Using 2-DE, 563 spots were detected, of which 64 spots displayed significant drought effect and 44 spots displayed a significant sex by drought interaction effect. The results suggest that the different responses to drought stress detected between the sexes have a close relationship to the changes in the expression of sex-dependent proteins, including, e.g. photosynthesis-related proteins, homeostasis-related proteins and stress response proteins. These proteins could contribute to a physiological advantage under drought, giving potential clues for understanding sexual differences in the performance of plants in different environments.