Sex-related differences in stress acclimation mechanisms in dimorphic, perennial plants

Background/Question/Methods . Sex-related differences in the physiological response of dioecious plants to abiotic stress have been poorly studied to date. This work explored to what extent sex may affect plant stress responses in plants. It was hypothesized that a greater reproductive effort in females may increase oxidative stress in leaves, particularly when plants are exposed to abiotic stress. Here, we summarize results from various studies performed in our laboratory, mainly using Mediterranean dimorphic species. 

Results/Conclusions . Measurements of oxidative stress markers revealed increased lipid peroxidation in females, particularly during periods of increased reproductive effort. In-depth physiological causes of enhanced lipid peroxidation in females differed however depending on modular effects (reproductive vs. non-reproductive shoots), time of measurements (with contrasting results depending on season and even time of day) and hormonal status, which are all in turn inter-connected. Reduced photoprotection was associated with increased lipid peroxidation at midday in females relative to males. Enhanced lipid peroxidation in females was also observed at predawn, which was associated with increased lipoxygenase activity and reduced cytokinin levels. An analysis of the differences between reproductive (R) and nonreproductive (NR) shoots showed an enhanced photoprotective capacity in R shoots compared to NR shoots in females. It is concluded that (i) females generally exhibit higher lipid peroxidation in leaves than males, but only when sex-related differences in reproductive effort are the highest, (ii) this may be associated with multiple factors, from sex-related differences in photoprotection to hormonal efects, and (iii) consideration of modular effects (i.e., R relative to NR shoots in females) is essential to understand adaptation mechanisms evolved by dimorphic species to withstand abiotic stress in their natural habitat.