关键词: 盐渍化, 根系分泌物, 长穗偃麦草, 碳水化合物

Abstract: The carbohydrates secreted by plant roots play a crucial role in modulating the carbon source supply and metabolic activity of soil microorganisms. To elucidate the response mechanism of root-secreted carbohydrates in salt-tolerant plants under varying intensities of salt stress, this study focused on Thinopyrum ponticum, a salt-tolerant forage species. Four levels of salt stress were established by adding NaCl: control (0% soil salt content), mild (0.2%), moderate (0.4%), and severe (0.6%). Non-targeted metabolomics technology was employed to analyze changes in the composition of root-secreted carbohydrates and their relationships with rhizosphere soil properties. The results demonstrated that: (1) Compared to the control, salt stress significantly decreased the contents of seven carbohydrate types—phenolic glycosides, glycosides, amino glycosides, D-glucosamine, hexose, α-D-galactoside, and indole—while markedly increasing monosaccharide content; (2) Glycosides were the predominant carbohydrates secreted by Thinopyrum ponticum roots, accounting for 72.25% ± 0.96% of the total relative abundance, whereas the remaining seven carbohydrate types ranged from 2.25% ± 0.50% to 8.50% ± 0.58%; (3) Root-secreted carbohydrates exhibited significant differences between the control and mild, moderate, or severe salt stress treatments, but no significant distinctions were observed among the latter three treatments; (4) Soil electrical conductivity and nitrate nitrogen content were identified as key factors responsible for the down-regulation of the seven carbohydrate types, while soil pH was the primary factor driving the up-regulation of monosaccharides.

Key words: Salinization, Root exudates, Thinopyrum ponticum, Carbohydrate