Sugars in postharvest lotus seeds were modified by 6-benzylaminopurine treatment through altering related enzymes involved in starch-sucrose metabolism

To investigate the effect of 6-benzylaminopurine (6-BA) treatment on starch-sucrose metabolism in postharvest lotus seeds, the lotus pods were immersed with 20 mg L−1 6-BA and stored at 25 ± 1 °C for 8 days. Our results revealed that 6-BA treatment not only delayed the browning of lotus pods and seeds, but also inhibited the respiration rate of lotus pods. Compared with controls, 6-BA treatment enhanced the deposition of starch, which was supported by the decreased amylase level. Contrary to the alteration of starch content, glucose and fructose contents in lotus seeds were reduced by 6-BA treatment through inhibiting the production of hexose from sucrose and starch degradations. However, the sucrose content in 6-BA treated group was higher than that in control groups until 6th day of storage, which was resulted from enhanced sucrose phosphate synthase (SPS) level and inhibited activities of synthase-cleavage (SS-cleavage) and invertase by 6-BA treatment. These results indicated that 6-BA treatment could maintain the starch and sucrose contents of lotus seeds by affecting related-synthetic or degrading enzymes involved in starch-sucrose metabolism, and alleviate postharvest senescence of lotus pods and seeds.