Physiological,Biochemical And Molecular Responses Of Soybean Induced By The Pathogenic Fusarium Graminearum Causing Soybean Root Rot

F.graminearum is an important pathogen of soybean root rot,which causes large loss in soybean yield and quality.Currently,chemical control has resulted in a range of problems including pesticide residue,soil and water pollution,drug resistance and destruction of the ecological environment.Screening and application of resistant soybean cultivars have commonly recognized as the most economica,effective and environment-friendly approach of disease management.However,there is a limited knowledge about the physiological and molecular mechanisms involved in soybean resistance against F.graminearum.Therefore,in this study the mechanism of action in soybean root against the pathogenic F.graminearum,the physiological and molecular responses including antioxidant enzyme activities(SOD,CAT,POD),malondialdehyde(MDA)contents,ROS production,isoflavonodes accumulation and defense gene expressions were examined in the moderately-resistant cultivar Nandou12 and susceptible cultivar Jiuyuehuang after inoculation with F.graminearum at different time points.In this study a higher level of malondialdehyde(MDA),and higher activities of catalase(CAT),superoxide dismutase(SOD)was observed in the resistant Nandou12 than those in the susceptible cultivar Jiuyuehuang,whereas for peroxidase(POD),the susceptible cultivar was much higher at the early stage of F.graminearum infection but decreased after 12 h as compare with resistance cultivar.ROS was quickly induced after F.graminearum infection in both cultivars but much more in the resistant Nandou12.Contents of four isoflavones were all significantly increased in both cultivars when compared to control,which were significantly higher in Jiuyuehuang compared to ND-12 when compred to ND-12,and significant difference in the total isoflavones content between control and F.graminearum imposed plants of both varieties.In addition,an earlier and greater induction of defense genes including PAL,IFS and PR10 were detected in ’Nandou 12’ compared to ’Jiuyue Huang’.