| Isoflavone is a class of secondary metabolites produced by legumes.Isoflavone plays an important role in the process of plant resistance to pathogens.Genistein and daidzein had toxic effect on SCN J2 and clould inhibit cyst hatching.In this experiment,two kinds of isoflavones were selected: genistein and daidzein.The effects of them play on the vitality at the concentrations of 10,50 and 100 μg/m L.The effects of them play on the nutrient content and antioxidant enzyme activities of SCN J2 at the concentrations of 100 μg/m Lwere determined.And the inhibitory effects of genistein and daidzein at the concentrations of 0.5,1and 2 mg/m L on soybean pathogenic fungi were determined.The results are as follows:Genistein and daidzein could affect the individual development of SCN J2.The body length got shoter,The length of needle and tail transparent zone became longer.The swing frequency of the treated SCN J2 is greatly reduced.The fluid leakage of SCN J2 increased and the oxygen consumption sharply decreased.With the increase of concentration and treatment time,the effect of isoflavone treatment on SCN J2 was more significant,and compare to daidzein the effect of genistein was more significant.The best effect showed in Genistein at 50,100 μg/m L and daidzein at 100 μg/m L,however daidzein at 10 μg/m L cloud barely effected SCN J2.The total sugar and soluble protein content of SCN J2 were decreased,the glycerol content was increased after isoflavones were used.The effect of genistein on the nutrient content of SCN J2 was relatively obvious in the early stage,but the difference between genistein and daidzein decreased with time past.The GST and CAT activity was disordered.At the beginning,the peak of GST activity in the genistein treatment group appeared earlier than the daidzein treatment group.However,in the genistein treated group,the trough of CAT activity showed in 24 h.At the end,the effect of genistein and daidzein is similar that the activities of two antioxidant enzymes are significantly reduced..Both two kinds of isoflavones could inhibited the grows of most pathogens at 2 mg/m L.For some pathogenic fungi,a higher inhibition rateshowed at the concentration of 1mg/m L.and under low concentration growth of little pathogenic fungi is promoted.Comprehensively speaking the effects of genistein and daidzein on soybean pathogenic fungi were better than other kinds,and they had better inhibitory effects on pathogens of stem and leaf diseases.Comparing two kinds of isoflavones,genistein has a better inhibition rate. |
