EXPRESSION OF A PATHOGENESIS-RELATED PROTEIN,WHEATWIN 1,FROM WHEAT AND ITS EFFECTS ON GROWTH AND MYCOTOXIN PRODUCTION OF ASPERGILLUS FLAVUS

Aspergillus flavus,a common pathogenic fungus found in tropical and subtropical climates,contaminates crops (corn,wheat and peanuts) post-harvest in favorable environmental conditions and can produce carcinogenic mycotoxins known as aflatoxin,which poses a serious threat to food quality and human health.It has been reported that several pathogenesis-related proteins exist in wheat kernel and the wheat cultivars that have higher resistance to storage fungi contain more pathogenesis-related proteins in their embryos.However,the effects of these pathogenesis-related proteins on the growth of storage fungi and mycotoxin production still need to be further demonstrated.In present study,the gene of wheatwin 1,encoding a pathogenesis-related protein,was cloned from wheat genomic DNA using PCR technique,inserted in to plasmid pGEX-4T-3 and expressed in Escherichia coli Origami (DE3) strain.After renaturation and purification of wheatwin 1,the inhibitory effects on growth of A.flavus and mycotoxin production were investigated.The results showed that the gene sequence encoding mature protein of wheatwin 1 is 378 bp and the inclusion body was obtained through the fusion expression of wheatwin 1 and glutathione S-transferase (GST) in E.coli.The inclusion body was refolded and then was digested by thrombin to obtain biologically active wheatwin 1,which exhibited ribonulcease activity and could hydrolyze RNA of A.flavus.The effects of wheatwin 1 on the growth of A.flavus and aflatoxin B1 production indicated that 100 μg/mL wheatwin 1 could significantly inhibit the germination of spore as well as accumulation of aflatoxin B₁,which provided experimental basis for further study of inhibitory mechanisms of wheatwin 1 on the growth of A.flavus and mycotoxin production.