Study On Relationship Between Sugar Metabolism Related Enzymes And Fruit Setting Or Sugar Accumulation In Fruit Of Watermelon

The assimilational substances of watermelon(Citrullus lanatus)translocated into fruit by stachyose,raffinose and sucrose.Change of of sugars and the stachyose,raffinose and sucrose metabolism related enzymes during fruit setting and development of watermelon: HeiJinbao,HeiMeiren,Jingxin No.1,Zhengza No.5,Xinong No.8 and Fengkangjinlong were studied.This trial at the same time studied the effects of on the changes of sugars and carbohydrate metabolism related enzymes during the process of melted ovary and shading, growth regulator treatment on sugar accumulation and changes of sugar metabolism related enzymes during setting stage and development of watermelon fruit of the Jingxin No.1.The results were showed as follows:1.The fructose and glucose content increased rapidly,the fructose content increased more rapidly especially in the six varieties of watermelon fruit during the fruit-setting stage of watermelon,and sucrose content increased a little,and it was low,and it was only 5%in the total of sugar.The activities ofα-Galactosidase(α-Gal),acid invertase(AI)and netural invertase(NI)was high and sucrose synthase(SS),sucrose phosphate synthase(SPS) activities were low during setting stage of watermelon.2.The fructose,glucose and contents increased rapidly in ovary of artificial pollinated watermelon,the fructose and glucose contents were high in ovary,and the extent of increase were big.And 3 kids of sugar were decreased in the ovary of unpollinated warermelon.Theα-Gal,AI,NI,SS and SPS activities in unpollinated watermelon young fruit were lower evidently than the pollinated fruit.The higherα-Gal,AI,NI activities and the rapid accumulation of fructose and glucose were the key of fruit setting of watermelon.3.The NI,AI,SS,SPS andα-Gal activities were high and were higher than those in control by 2,4-D and Zuogualing treatment during setting stage of watermelon young fruit. And the fructose,glucose and sucrose contents increased more rapidly than control.The sugar contents were increased slowly in shading watermelon young fruit,and the sucrose, fructose and glucose content were lower evidently than control.And theα-Gal,AI,NI,SS and SPS activities of shading watermelon fruit were lower than that of control.4.It accumulated fructose and glucose mainly in the expansion period of watermelon fruit.The fructose and glucose contents of early varieties reached the peak in 22～26 days after anthesis then decreased,while the sucrose content began to accumulate rapidly in round 22 days after anthesis,the fructose and glucose contents of late-maturing varieties accumulated to peak value later than early varieties 4～8 days.Theα-Gal,AI and NI activities were higher,and the SS and SPS activities were lower in the expansion period of watermelon fruit.With the developing of fruits,α-Gal activity decreased and then rised,NI and AI activity decreased gradually,SS and SPS was rising gradually during ripening.The higherα-Gal,AI and NI activities closed to the accumulation of fructose and glucose,and the increase of SS and SPS were consistent with the sucrose content.5.Shading decreased theα-Gal,AI,NI,SS and SPS activities in the developing of watermelon fruit,and the fructose,glucose and sucrose contents decreased evidently. Using GA₃ treatment in the expansion period of watermelon fruit,it made thatα-Gal,NI and AI activities increased,SS and SPS activities decreased,and the fructose and glucose contents increased significantly,the sucrose decreased.Watermelon for months,with ethylene treatment,the dynamic changes of fructose,glucose and sucrose contents were accord to control,the ethylene improved theα-Gal,AI,NI,SS and SPS activities,promote the accumulation of fructose,glucose and sucrose,but theα-Gal,AI,NI,SS and SPS activities were lower than control,and the fructose,glucose and sucrose contents were also lower than control.