Study On The Mechanism Of Puffing Formation In Satsuma Mandarin 'Miyagawa'

Citrus unshiu is the main citrus varieties in Zhejiang Province. Fruit puffiness is a physiological disease prevalently developed in citrus fruits during maturation or storage stage, while currently the puffing mechanism remains largely unknown. In this paper, 'Miyagawa' fruit and the resistance of puffing varieties bud mutant were as experimental materials , according to the characteristics of anatomy and physiology, the morphological changes of fruit development in the early stage of fruit development (40days after flowering) to fully mature fruit (197days after flowering) and the changes in cell and subcellular levels were compared, With the fruit at different developmental stages of the activity of antioxidant enzymes (SOD, POD, CAT) and the changes of MDA content, analyzing the mechanism of the 'Miyagawa' puffiness character formation, and the main results are as follows.By observing the fruit morphology,the results showed that since 85 days after flowering,'Miyagawa' fruit behaved that fruit pedicle prominent, the fruit peel was rough and the mesocarp was thick. Fruit maturity is about 10 days slower than bud mutant, and 'Miyagawa' peel prone to puffing;Through the analysis of antioxidant enzyme activity (including SOD, POD, CAT) and MDA contents in in different growth process. It was found that 'Miyagawa' has activities of the antioxidant system-related enzymes had an obvious change at 85 days after flowering , to conjecture that'Miyagawa' fruit occured puffing critical period at 85 days after flowering.To observed by using transmission electron microscopy, The 'Miyagawa' and bud mutant cell arrangement and subcellular structurechanges were compared in the developmental process. It was found that there were significant differences between 'Miyagawa' and bud mutant at 85 days after flowering . The 'Miyagawa' chloroplast has based lamellae disappeared and osmophilic lipids increased. The cell wall structure became loose and appeared a phenomenon of wall separation. Until the fruit matured,'Miyagawa' cells had been fully dispersed deformation,and cell membrane fracture degradated,the organelle was atrophied in the cell center. While the bud mutant cells had a small degree of osteoporosis and less wall separation.To sum up, 85 days after flowering is the critical period of 'Miyagawa' occurred puffing.