Photosynthetic and biochemical responses to multiple abiotic stresses in Deschampsia antarctica, Poa pratensis, and Triticum aestivum

Abstract

Photosynthesis is inherently limited by abiotic stresses like extreme temperatures, water deficit, and nutrient deficiency. However, the combined impacts of these multiple stresses on photosynthetic capacity remain largely underexplored. This study investigates the effects of low temperature, drought, and nutrient scarcity on the photosynthetic responses of three distinct grass species: the polar Deschampsia antarctica (DA) from Antarctica, the cosmopolitan Poa pratensis (PP) from the Arctic, and the crop species Triticum aestivum (TA). Under optimal conditions, both DA and PP exhibited lower photosynthetic rates compared to TA. Crucially, when subjected to a combination of multiple abiotic stresses, DA demonstrated a significantly less pronounced photosynthetic decline than TA. This remarkable ability to maintain higher photosynthetic efficiency under suboptimal conditions not only boosts net carbon assimilation but also enhances overall plant performance in harsh environments. Our results reveal that DA's superior performance under multiple stress conditions is attributed to a unique combination of structural and biochemical traits. These include constitutively higher leaf mass per area (LMA) and cell wall hemicellulose content. Furthermore, DA showed a balanced strategy of reduced investment in photosynthetic machinery coupled with enhanced photoprotection and antioxidant status (indicated by an increased xanthophylls + carotene/chlorophylls ratio), a combination not observed in PP or TA. These findings underscore that DA possesses specific physiological adaptations, enabling it to successfully cope with simultaneous multiple abiotic stresses more effectively than PP and TA.