Juglans sigillata, an endemic species in China, serves as a vital local economic resource. Aluminum (Al) stress caused by soil acidification can potentially threaten the growth of J. sigillata. This study aimed to elucidate the mechanism of the alleviation of Al stress by silicon (Si) in J. sigillata. The results showed that Si could reduce the Al accumulation of walnut and improve root growth under Al stress. Si also increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities and soluble sugar and proline contents, reduced malonaldehyde (MDA) and H2O2 contents and the O2- production rate, and maintained the homeostasis of cells. Transcriptome analysis revealed significant up-regulation of genes encoding plant hormones (ABA, IAA, and CTK) and photosystem II components (PsbO, PsbQ, PsbW, and PsbY). Under Al stress conditions, the application of exogenous Si notably enhanced the expression of genes associated with heavy metal transport (CAX, PAA, ABC, HMA, NRAMP, and ZIP). Comprehensive transcriptome and metabolomics analysis showed that Si regulated secondary metabolite metabolism via the phenylalanine, galactose, and tryptophan pathway, altered cell wall composition, increased energy supply, and reduced auxin synthesis in root tip transition zones to alleviate Al toxicity of J. sigillata. In summary, the application of Si significantly alleviated Al-induced damage in J. sigillata.

来源平台：PLANT PHYSIOLOGY AND BIOCHEMISTRY