Abstract: 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.

Key words: lotus seeds, 1-(2-chloropyridin-4-yl)-3-phenylurea, storage quality, cell wall polysaccharides, ultrastructure