猕猴桃果实贮藏期间细胞壁多糖物质降解特性及组织结构差异分析

Degradation Characteristics of Cell Wall Polysaccharides and Differences in Tissue Structure of Kiwifruit Fruits During Storage

为了深入了解猕猴桃果实采后细胞壁多糖物质降解及组织结构变化与果实贮藏性的关系,本研究以红阳和华特猕猴桃果实为试材,对25和4℃贮藏期间的细胞壁多糖物质含量及果胶降解酶活性进行测定,并比较两品种果实在25℃贮藏期间的细胞显微结构和钙组分含量差异。结果表明,在25和4℃贮藏条件下,随着贮藏时间的延长,红阳和华特猕猴桃果实中半纤维素(HCL)、纤维素(CL)和共价结合型果胶(CSP)含量不断降低,水溶性果胶(WSP)含量不断上升,离子结合型果胶(ISP)含量相对稳定。红阳猕猴桃各细胞壁多糖组分含量变化速度较快。两品种猕猴桃果实硬度均与WSP含量呈显著负相关,与CSP含量呈显著正相关。果胶降解酶活性检测结果显示,25℃贮藏前期,红阳猕猴桃中果胶酸裂解酶(PL)和β-半乳糖苷酶(β-Gal)活性显著高于华特;贮藏中后期,红阳中果胶甲酯酶(PME)活性显著高于华特。4℃贮藏期间,红阳中PME活性仍显著高于华特;4℃贮藏前期,红阳中β-Gal活性与华特无显著差异,而PL活性低于华特。相关性分析表明,25℃贮藏期间,与红阳和华特果实软化显著相关的果胶降解酶分别是PME和PL;4℃贮藏期间,与华特果实软化显著相关的果胶降解酶是PME。25℃贮藏期间,华特果实表皮细胞层数更多,果肉细胞排列更紧密;华特果实含更多草酸钙晶体。此外,25℃贮藏期间华特果实的水溶钙、果胶钙、磷酸钙和草酸钙含量均显著高于红阳。本研究为揭示猕猴桃果实采后细胞壁多糖物质降解及组织结构变化特性提供了理论依据。

In order to reveal the relationship between the degradation of cell wall polysaccharides or tissue structure changes and storage ability of kiwifruits,the degradation of characteristics of polysaccharides in the cell wall of Hongyang and White kiwifruit fruits were studied during storage at 25℃and 4℃,and the differences of cell microstructure and calcium content between the two fruits during storage at 25℃were compared.The results showed that the contents of hemicellulose(HCL),cellulose(CL)and covalent soluble pectin(CSP)of Hongyang and White kiwifruits decreased continuously,while the contents of water soluble pectin(WSP)increased continuously,and the contents of ironic soluble pectin(ISP)remained relatively stable under 25℃and 4℃storage.The content of polysaccharide in cell wall of Hongyang kiwifruit changed faster.There was a significant negative correlation between fruit hardness and WSP content,and a significant positive correlation between fruit firmness and CSP content.In the early stage of 25℃storage,the activities of pectate lyase(PL)andβ-galactosidase(β-Gal)of Hongyang kiwifruit were significantly higher than that of White.The activity of pectin methylesterase(PME)in Hongyang was significantly higher than that in White during the middle and late storage.When stored at 4℃,the PME activity of Hongyang was significantly higher than that of White.In the early stage of storage at 4℃,there was no significant difference betweenβ-Gal activity,while Hongyang PL activity was lower than White.Correlation analysis showed that pectin degrading enzymes significantly correlated with fruit softening of Hongyang and White at 25℃were PME and PL,respectively.At 4℃,the pectin degrading enzyme significantly related to White fruit softening was PME.During storage at 25℃,the number of epidermal cell layers of White fruit was more,and the arrangement of flesh cells was closer.The pulp cells of White contains more calcium oxalate crystals.In addition,the contents of water-soluble calcium,pectin calcium,calcium phosphate and calcium oxalate in White were significantly higher than those in Hongyang under 25℃storage.This study provided theoretical basis for revealing the degradation of cell wall polysaccharides and the changes of tissue structure of kiwifruit fruit after harvest.