Altitudinal adaptation and plasticity of physiological and proteomic variation in Polygonum viviparum under alpine...

To elucidate the adaptation mechanisms of Polygonum viviparum (an alpine forage grass and medicinal plant), the adaptive variation and plasticity in P. viviparum leaves along three altitudes (2300, 3200, and 3900 m) were investigated. The results showed that the stomata density, carotenoid/chlorophyll ratios, and de-epoxidation state of xanthophyll cycle pool significantly increased with increasing altitude, whereas the stomatal aperture length and total chlorophyll content decreased. At 3200 m, the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and antioxidant enzyme activities (CAT, POD and SOD) rose sharply, and the non-structural carbohydrates (NSC) accumulated markedly. At 3900 m, the proline content and non-photochemical quenching (NPQ) significantly increased, conferring tolerance to high-altitude environments. Furthermore, a total of fifty-nine differentially abundant proteins were identified and functionally characterized by proteomic analysis, mainly involved in photosynthesis, bioenergy and metabolism, defense, transcription and translation, and transport. Hierarchical clustering indicated that these proteins participated in a dynamic network underlying high-altitude adaptation in P. viviparum, mainly including metabolic and bioenergetic remodeling, photosynthetic optimization, photo-protection, as well as antioxidant activation. Taken together, P. viviparum might exhibit acclimation performances at 3200 m and employ tolerance mechanisms to endure the harsher environments at 3900 m. This study provides novel insights into the altitudinal adaptation strategies of P. viviparum under heterogeneous alpine environments.