Salicylic acid alleviates aluminum-induced inhibition of biomass by enhancing photosynthesis and carbohydrate metabolism in Panax notoginseng

Aims Determine whether salicylic acid (SA) can alleviate the inhibitory effects of Al stress on dry matter accumulation in Panax notoginseng , and to investigate the mechanism by which the SA regulates photosynthesis and carbohydrate metabolism. Methods Effects of SA on the biomass of P. notoginseng and the concentration of Al in leaves under Al stress were evaluated. SA and the scavenger paclobutrazol (PAC, SA synthetic inhibitor) were used to assess the effects of SA on photosynthesis and the metabolism of total nonstructural carbohydrates (TNC) in P. notoginseng . Results SA reduced Al by 13.23% in the leaves of P. notoginseng under Al stress. It also promoted the synthesis of carbohydrates in the leaves and their transport to the roots . Additionally, SA alleviated the Al-induced reduction of chlorophyll (Chl) by upregulating the expression of Chl synthesis genes ( CHLM , CHLG , HEMB1 , HEMC, and HEME ) and downregulating the degradation genes ( CLH2 and PPH1 ). Concomitantly, the rubisco activase (RCA) and rubisco enzyme activities were promoted by upregulating the expressions of the RCA , rbcL , and rbcS genes via treatment with SA, thereby restoring the synthesis and metabolism of TNC. Furthermore, SA attenuated the decrease in photosynthetic capacity and photosynthesis system II photochemistry efficiency in Al-stressed plants. Furthermore, SA significantly reduced the H 2 O 2 concentration by 12.22% under Al stress. Conclusions By regulating photosynthesis-related genes and photochemical processes, SA promoted photosynthesis and enhanced leaf carbohydrate synthesis under Al stress. Thus, SA enhanced the production of P. notoginseng biomass, ultimately reducing the inhibitory effects of Al.