Study On Mechanism Of Peanut Nutrition Utilization During Aspergillus Flavus Colonization

Aflatoxin,a secondary metabolite,which is a competent carcinogenic substance mainly produced by Aspergillus flavus,can result to crops contamination such as peanut,and cause the economic and health damages for human beings.Based on the resistant peanut GT-C20(R)and susceptible peanut Tifrunner(S)as the research object,through the experiment we found that aspergillus flavus infection of peanut seed is more than just stay on the surface of the seed coat,through vegetative hyphae the aspergillus flavus went through the peanut,and within a large number of proliferation inside,to destruct the cell tissue and function,for provide nutrients needed for its growth.In within 48 h,aspergillus flavus infection has rapidly through the peanut seed,and into cotyledon part of susceptible peanut.By using direct titration,soxhlet extraction and ninhydrin colorimetric method,the total sugar,reducing sugar,fat,fatty acids,protein and amino acids were determined before and after peanuts infected with aspergillus flavus.Using paraffin section and transmission electron microscopy(TEM)respectively,the morphological changes of different resistant peanuts were observed before and after peanuts aspergillus flavus infected.Using real-time quantitative PCR assay to determine the three hydrolase gene expression,which is related with nutrient utilization in aspergillus flavus.The universal contamination of peanut by aspergillus flavus can be observed by this experiment.As the peanut nutrient varies,the the degree of infection by aspergillus flavus was different.The lipid and sugar were the key nutritional factors for aspergillus flavus infection.As the growth of aspergillus flavus differs,so were peanut nutrients consumption.Lipids and sugar change significantly,especially the changes of fat and reducing sugar.During aspergillus flavus infection of peanuts,reducing sugar of peanut is the main carbon source of growth.By real-time quantitative PCR method,the three hydrolase gene expression of aspergillus flavus were detected,the expression pattern of three genes in susceptible peanut and resistant peanut was studied.In susceptible peanut,the results show that in 1-7 days,protease gene expression is less than the lipase gene expression,the results were consistant with the change of peanut protein content.On resistant peanut,expression inhibition period of 3 to 4 days were detected,then the rising trend were presents,the result that resistance of resistant peanut to aspergillus flavus were shortdated,rather than outright resistant.By exploring the influence of aspergillus flavus with susceptible and resistant peanut to understand the hydrolysis enzyme genes,nutrients and morphology changes,and to provide more detailed basis in resistant peanut breeding for aflatoxin resistant.