Cell wall polysaccharides are closely related to fruit firmness. Firmness loss results in softening and restricts postharvest storage of plum fruit at ambient temperature. This study aimed to investigate the effects of valeric acid (VA) treatment on fruit firmness and cell wall polysaccharides metabolism in plum fruit. Results showed that 10 mg L⁻¹ VA treatment delayed the decline of plum fruit firmness. VA-treated plum maintained higher contents of protopectin, cellulose, hemicelluloses, and lignin but lower water-soluble pectin (WSP) amount. Lower activities of polygalacturonase (PG), pectinate lyases (PL), pectinesterase (PE), β-galactosidase (β-GAL), cellulase, hemicellulase but higher activities of phenylalanine ammonia lyase (PAL), 4-coumaroyl-CoA ligase (4CL) and peroxidase (POD) were observed in VA-treated fruit. These results suggested that VA treatment delayed the depolymerization of cell wall polysaccharides via inhibiting activities of degrading-enzymes. Moreover, lignin metabolism was regulated by VA treatment. Altogether, VA treatment regulated cell wall polysaccharides metabolism, then subsequently alleviated firmness loss and prolong storage-life of postharvest plum fruit.

细胞壁多糖与果实硬度密切相关。硬度损失会导致变软并限制李子果实在环境温度下的采后储存。本研究旨在研究戊酸（VA）处理对李子果实硬度和细胞壁多糖代谢的影响。结果表明，10 mg L ^-1VA处理延缓了李子果实硬度的下降。VA 处理的李子保持较高的原果胶、纤维素、半纤维素和木质素含量，但水溶性果胶 (WSP) 含量较低。聚半乳糖醛酸酶 (PG)、果胶裂解酶 (PL)、果胶酯酶 (PE)、β-半乳糖苷酶 (β-GAL)、纤维素酶、半纤维素酶的活性较低，但苯丙氨酸氨裂解酶 (PAL)、4-香豆酰辅酶 A 连接酶 (4CL) 的活性较高) 和过氧化物酶 (POD) 在 VA 处理的果实中观察到。这些结果表明VA处理通过抑制降解酶的活性来延迟细胞壁多糖的解聚。此外，木质素代谢受 VA 处理调节。总之，VA处理调节了细胞壁多糖代谢，随后减轻了李子果实的硬度损失并延长了贮藏期。