氯吡苯脲处理对莲子细胞壁多糖降解特性的影响

为探究氯吡苯脲(1-(2-chloropyridin-4-yl)-3-phenylurea,CPPU)处理对莲子采后细胞壁多糖降解特性的影响,以‘太空莲36号’莲蓬为试材,以清水浸泡为对照,以5 mg/L CPPU对莲蓬进行处理。结果表明:CPPU处理可有效维持莲蓬及莲子较好的表型,保持莲子脆嫩口感;CPPU处理的莲子含有更高的共价结合果胶含量和更完整的纤维素多糖碳链结构;CPPU处理可有效抑制果胶甲酯酶、多聚半乳糖醛酸酶等果胶降解酶和外切葡聚糖酶、β-葡萄糖苷酶、内切葡聚糖酶等纤维素降解酶的活力,从而延缓共价结合果胶降解及水溶性果胶、离子结合果胶积累,并保持莲子纤维素和半纤维素含量;同时,CPPU处理保持了莲子细胞壁结构和纤维素微纤丝的形态,并抑制了细胞的质壁分离。因此,CPPU处理有利于抑制莲子细胞壁多糖的降解,更好地维持细胞完整性,保持莲子的口感,从而延缓其采后衰老。本实验为鲜莲蓬和莲子的采后保鲜提供理论依据和技术支持。

Effect of 1-(2-Chloropyridin-4-yl)-3-phenylurea Treatment on Degradation Characteristics of Cell Wall Polysaccharides in Lotus Seeds

In order to investigate the effect of 1-(2-chloropyridin-4-yl)-3-phenylurea (CPPU) treatment on the degradation of cell wall polysaccharides in lotus seeds, lotus pods from the cultivar ‘Taikonglian 36’ were treated with 5 mg/L CPPU. The samples treated with distilled water were used as controls. It was found that CPPU treatment could significantly maintain good phenotype of lotus pods and seeds, as well as crisp and tender taste of the seeds as compared with control. Meanwhile, CPPU treatment increased covalently bound pectin content in lotus seeds and maintained the structural integrity of cellulose polysaccharide chains. In addition, CPPU treatment inhibited the activity of pectin-degrading enzymes such as pectin methylesterase (PME) and polygalacturonase (PG) and the activity of cellulose-degrading enzymes such as cellobiohydrolase 1 (C1), β-1,4-endoglucanase (Cx) and β-glucosidase in lotus seeds, thus degrading the degradation of covalently bound pectin and the accumulation of water-soluble pectin and ion-bound pectin and maintaining cellulose and hemicellulose. CPPU treatment could maintain the integrity of the cell wall and the morphology of cellulose microfibrils in lotus seeds and inhibited plasmolysis. Therefore, CPPU treatment can inhibit the degradation of cell wall polysaccharides, maintain cell integrity in lotus seeds as well as the taste and delay postharvest senescence of lotus pods and seeds. This experiment can provide theoretical and technical support for postharvest preservation of lotus pods and seeds.