Phenotypic plasticity facilitates alterations in life-history strategies under combinations of environmental stresses

Plants developed various reversible and non-reversible acclimation mechanisms to cope with the multifaceted nature of abiotic stress combinations. We hypothesized that in order to endure different combinations of stresses, plants elicit unique acclimation strategies through specific alterations of their energy balance. A system biology approach, integrating physiological, metabolic and transcriptional data, was applied to investigate Brachypodium distachyon acclimation strategies to double and triple stress combinations of salinity, drought and heat. In addition, the various trade-offs between functional and performance traits and their effects on plant fitness were analyzed. We found that under combination of stresses plants exhibited phenotypic and metabolic plasticity that differentially affected plant life-history strategy. Combination of drought and heat resulted in escape strategy, while under combination of salinity and heat plants exhibited avoidance strategy. On the other hand, under combinations of salinity and drought, with or without heat, plant fitness was severely impaired. Under the combined stresses, plant life-history strategies were shaped by trades-off between traits and the limits of phenotypic and metabolic plasticity. This study shed light on unique acclimation mechanisms that can contribute to grass fitness and possibly to their dispersion under changing environments.