‘秦冠’和‘富士’质地差异的解剖学观察及相关酶活性研究

Study on Anatomy and Fruit Texture Related Enzymes in Apple (Malus×domestica) Cultivars ‘Qinguan' and ‘Fuji'

以质地品质差异明显的2个苹果品种‘富士’和‘秦冠’为试材,观察发育过程中果肉细胞显微结构,测定果实的脆度和硬度及细胞壁相关代谢酶和淀粉酶(AM)的活性,并进行相关性分析,找出导致这2个品种质地差异的关键因素。结果表明:1花后85d前,2个品种的果肉细胞大小相似,而在花后85d时,‘富士’果肉细胞明显增大,显著大于‘秦冠’果肉细胞,并且在花后115d时细胞又一次显著增大。而‘秦冠’果肉细胞仅在花后100d时显著增大,此后增长不显著。2在果实发育过程中,‘秦冠’和‘富士’的果实硬度和脆度均逐渐降低。‘富士’果实的脆度一直较‘秦冠’高。花后100d前‘富士’果实的硬度高于‘秦冠’,而花后115d至果实成熟期间均显著低于‘秦冠’。3花后115d以后‘秦冠’的果胶甲酯酶(PME)活性明显高于‘富士’,而‘富士’的β-半乳糖苷酶(β-Gal)活性明显高于‘秦冠’。相关性分析表明,多聚半乳糖醛酸酶(PG)和PME活性与‘秦冠’的质地呈显著负相关,而β-Gal活性与‘富士’的质地呈显著负相关。可见,随着果实生长发育,‘秦冠’和‘富士’质地品质的差异除表现在果肉细胞显微结构上外,还与一些代谢酶密切相关,PG和PME是‘秦冠’果实质地变化的关键酶,而β-Gal在‘富士’质地变化中发挥关键作用。

Cultivars‘Fuji＇and ‘Qinguan ＇were chosen as material for their distinct differences on fruit texture.Microstructure of pulp cells was observed,firmness and fracturability of fruit and activity of cell wall-modifying enzymes and enzyme AM were measured during fruit development.The correlation analysis was conducted.The results showed that,（i）The pulp cell size had been similar between two cultivars by 85 days after flowering,however,pulp cells of‘Fuji＇increased obviously at the period of 85 days after flowering,whose size was significantly larger than ‘Qinguan＇,and increased again at the period of 115 days after flowering.While,pulp cells of‘Qinguan＇only increased significantly at the period of 100 days after flowering,and no significant growth since then.（ii）Firmness and crispness both gradually reduced during fruit development.Higher fracturability was found in ‘Fuji＇at the whole stages.Firmness was higher in‘Fuji＇than in‘Qinguan＇prior to 100 days after flowering,however,which was reversed from 115 days after flowering to fruit picking period.（iii）Since 115 days after flowering.The activity of pectinesterase（PME）had been significantly higher in ‘Qinguan＇than in‘Fuji＇,but the activity ofβ-Gal had been higher in‘Fuji＇than in‘Qinguan＇.Activities of polygalacturonase（PG）and PME were significantly negatively related to the texture of‘Qinguan＇,whileβ-Gal activity was significantly negatively related to the texture of‘Fuji＇fruit.In conclusion,distinct texture of apple cultivars‘Fuji＇and‘Qinguan＇was not only based on microstructure of pulp cells,but also closely related to several modifying enzymes.Enzymes PG and PME were vital for‘Qinguan＇,whileβ-Gal played a key role in the formation of texture for‘Fuji＇.