Physiological ROROe And Regulation OfAllene Ojde Synthasein Postharvest'Huang－Hua'Pear(Pyrus Pyrifolia Nakai)During Th

The experiments were carried out in 2000 and 2001 at Zhejiang University. The Chinese pear (Pyrus pyrifolia Nakai. cv. 'Huang-hua') fruit was used to investigate the change of AOS activity and its relationship with other senescence-related factors after harvest.Pear is a climacteric fruit. No significant effect was observed on firmness of 'Huang-hua' pear stored at different temperatures. Fruit floss was an important characteristic in postharvest 'Huang-hua' pear during fruit ripening and senescencing.AOS is a limit-rating enzyme of JA synthesis in LOX pathway, it exists in plants ubiquitously. It has been investigated that AOS participates in the regulation of growth, development, ripening, senescencing, and defense process. This thesis states the characteristic of AOS, its roles in the pathway of JA synthesis and its interaction with other factors related to ripening and senescencing.For understanding the physiological effects of AOS on fruit senescence, 'Huang-hua' pear of different harvest time was used. The peaks of AOS activity in different maturity fruits occurred on the 10-12th day after harvest, prior to the peaks of ACC synthase and ACC oxidase activity, ACC content, as well as the climacteric peak of ethylene production, but posterior to the peaks of LOX activity and O2" production (Figs.4-1-4-4). When the fruits were stored at 1 癈, AOS activity and other senescence-related factors were markedly inhibited, the fruit senescence was delayed as well. It was suggested that AOS, like LOX, being one of the up-stream regulators in ethylene biosynthesis.Different treatments of temperature and polyethylene film bag packing were carried out for investigating its effects and physiological basis during 'Huang-hua' pear storage. 'Huang-hua' pear fruit was a typical climacteric fruit after harvest, and the fruit senescence-related factors, such as LOX activity, 02" content, AOS activity, ACC synthase activity, ACC content, ACC oxidase activity and ethylene production, changedwith peaks at 20 "C. The activities of LOX, AOS, ACC synthase, ACC oxidase and the accumulation of O2 " , ACC content and ethylene synthesis were inhibited when stored at 1癈. And the severity of flesh floss and fruit decay was lightened. Low temperature combined with polyethylene film bag packing (PEF1 and PEF2) could further decrease the rate of weight loss, flesh floss, and fruit decay and keep preferable freshness. When PEF1 and PEF2 packing fruits were transferred to shelf life at 20 "C after storage at 1癈. The activities of LOX, AOS, ACC synthase, ACC oxidase could be suppressed and the accumulation of 02 " , ACC content and ethylene production were slowed down to a certain extent, especially during the shelf life after 60 d storage. PEF1 and PEF2 packing fruit could maintain higher firmness as well, and the effects became more distinct along with the storage period, there existed no significant difference between PEF1 and PEF2 treatments. Two-month was favorable for 'Huang-hua' pear fruit storage at 1癈 and combined with polyethylene film bag packing, the storage period would be further prolonged to three months.