Study On Physiological Characteristics Of Peanut Resistance To Aspergillus Flavus

Peanut is the important industrial crop and oil crop in China. And is important sources of edible oil and protein with rich nutritional value. It is the third major grain and oil crops in Fujian province. At the same time, peanut is the one of most susceptible crops to Aspergillus flavus, metabolite produced after infection of aflatoxin is a strong carcinogen. Aflatoxin contamination has seriously affected the peanut production, processing and human health. Aplicationt of disease resistant variety was the most effective measure against Aspergillus flavus effection. But most of peanut varieties in Fujian province were low resistant to Aspergillus flavus. Therefore, on the basis of the existing, choose effective resistance index, establish a resistance evaluation technology system of a set of comprehensive, fast, stable, help in the selection of high-resistance peanut varieties, at the same time as the peanut resistance mechanism and identification of resistant and susceptible varieties and provide a theoretical basis.In this paper, we take four varieties of peanut which were widely planting in Fujian province as research materials, inoculated with high yield toxic strains which isolates from Aspergillus flavus strains. After infecting, the of catalase (CAT)activity, superoxide dismutase (SOD)activity, cell membrane permeability changes, and the changes of malondialdehyde (MDA), soluble protein, phenols and flavonoids contents in peanut seed were determined, which to study the physiological and biochemical reaction of the different resistant varieties. Then screened the physiological and biochemical index to identificate the resistant cultivars.100 peanut seeds of each peanut varieties were inoculated with Aspergillus flavus. The results showed that cultivar Yu 22 had no infected seed, Minhua 6 appeared 33 infected seeds, Quanhua 627 appeared 28 infected seeds, Quanhua 646of appeared 47 infected seeds. According to the infection index of peanut kernels of Aspergillus flavus, cultivar Yu 22 belonged to the resistant varieties,Minhua 6 and Quanhua 627 belonged to middle susceptible varieties, Quanhua 646 belong to susceptible varieties. Inoculated with Aspergillus flavus increased plasma permeability and MDA contents in susceptible varieties seeds increased, There was a positive correlation between the changes of membrane permeability and MDA conten. This indicated that infected seeds promoted the membrane damage and enhancement of lipid peroxidation in susceptible varieties. But the relative membrane permeability in resistant variety seeds was lower than in the control resistant variety seeds. This show the resistant variety probably through decreas ing the membrane permeability against Aspergillus flavus.The SOD, CAT activities of in seed of resistant variety were higher than that of susceptible varieties without inoculation. The SOD, CAT activities of susceptible varieties decreased inafter inoculation, but the changes of enzye activities in resistant variety was not obvious. The content of anthocyanins, total phenolics and flavonoids in resistant varieties seeds had little change after inoculation, but in susceptible varieties seeds increased significantly. The content of soluble protein in resistant varieties seeds was higher than that of the three susceptible cultivars before inoculation. And after inoculation, the content of soluble protein increased significantly in susceptible varieties,but had little change in resistant variety.The role and resistant mechanism for protein content in resistant cultivar need study further.