Study On The Fat Metabolism And Esterase Isozyme Of Soybean

Soybean is a main crop as both food and oil. Studies on fat metabolism mechanism of soybean for improving soybean seed quality and promoting the development have great significance.This work was conducted with field plot experiment, frame tests (pot without bottom) and germination in the experimental station of Northeast Agricultural University (NEAU) in 2008~2009. Three quality types of five soybean varieties were used as test materials: Dongnong 42(High protein), Heinong 43 (High protein ), Suinong 14(Common), Heinong 45(High Oil), Dongnong 47(High Oil), which for germination test and field plot experiment; three nitrogen levels, low, mid and high were chosen for nitrogen for only both SN14. Study on the effect of fat accumulation and translocation and nitrogen levels on bands and activity of esterase isozyme, results were shown as follows:The fat content showed an increasing trend with the increase of the days after flowering in five tested cultivars, the content of fat was slowly increased between 26~32 days after flowering, its fastest growing stage was between 32~50 days after flowering, which increased slowly between 50~68 days after flowering, and up to the maximum in maturity. The changes of fat content showed the trend of down - up - down during germination of soybean, fat content was up to the maximum between 5~6 days after germination, from 7 days it began to decrease.Ratio of fatty acid composition was obviously difference during germination and pod development. Ratio of Linolenic acid, Stearic acid, palmitic acid decreased, that of Linoleic acid increased, and which of Oleic acid increased then decreased during pod development. Ratio of Linoleic acid and Linolenic acid fluctuant increased when germination, that change of Oleic acid, Stearic acid, palmitic acid were not obvious, there was no regular change among varieties.The days after flowering with proportion of Oleic acid had positive correlation, with the proportion of Stearic acid, palmitic acid, linolenic acid was negative correlation, however, individual species could not reach the significant level during development of soybean pods; there were different correlation with fat and the proportion of its composition, Linoleic acid, Oleic acid had significant or very significant positive correlation with Fat, Linolenic acid, Stearic acid , Palmitic acid had significant or very significant negative correlation with Fat. There were correlation between the individual fatty acid composition in the process of germination, Oleic acid and linoleic acid was very significant negative correlation; Oleic acid and Palmitic acid showed a significant positive correlation; linoleic acid and stearic acid, palmitic acid had a significant negative correlation, the correlation between other fatty acids were not significant.23 esterase isozyme bands appeared from 20 days after flowering to 62 days during development of soybean pods, Rf values ranged from 0.170 to 0.795, there were differences between esterase isozyme activity and bands for different stages and varieties; At the early stage of pod development, a few bands appeared and concentrated in the middle region; then more bands appeared as pods growing and bands appear near the anode area; bands decreased when maturity, and enzyme activity decreased in middle region, bands appears near the cathode region. There was less number of enzyme bands during germination than development of soybean pods, 8 enzyme bands appeared, Rf values ranged from 0.170 to 0.580, there were little Changes of Enzyme spectrum, relatively stable. Enzyme bands which appeared in germination Also appeared in development of soybean pods among five varieties, which showed that part of the esterase isozyme played a role both in fat accumulation and catabolism.Enzyme activity was relatively high between 32 ~ 44 days after flowering and 62 to 68 days after flowering of five soybean varieties. There were changes of enzyme activity during germination, higher activity in the soybean seed without germination, enzyme activity rapidly decreased after germination, enzyme activity increased at 4 days, which reached the maximum activity except Heinong45.There were different correlation with esterase isozyme activity and the fat and its composition of five varieties during development of soybean pods, there was a significant positive correlation of Oleic acid and enzyme activity in Heinong43, other varieties did not reach significant level. Linolenic acid and enzyme activity showed a significant negative correlation in Dongnong42 and Heinong43, Stearic acid and enzyme activity showed a significant or very significant negative correlation in Heinong43, Suinong14 and Heinong45; palmitic acid and enzyme activity showed a significant or very significant positive correlation in five varieties besides Suinong14.The order of content of fat was N300>N100>N0 At the stage of mature(68 days after flowering), and reached the significant difference, which showed that Yield of soybean was obviously affected by N levels.