Alternaria alstroemeriae F1 inhibits aspergillus flavus growth and weakens aflatoxins biosynthesis

Aspergillus flavus is a saprophytic fungus that can infect economic crops and produce aflatoxins with high toxicity, carcinogenicity and mutagenicity, which is a serious threat to human and animal health. In order to find a more efficient biological control way to inhibit A. flavus and its production of aflatoxins, we isolated 7 fungal strains F1-F7 from Camellia sinensis. Only the strains F1 and F2, isolated from the flowers of C. sinensis and identified as Alternaria alstroemeriae and Alternaria burnsii, exhibited significant antagonistic activities against A. flavus. In addition, the contents of AFB1 and AFB2 significantly decreased when A. flavus was antagonized by Alternaria alstroemeriae F1. By the transcriptome and qRT-PCR analysis, some genes related to A. flavus growth and secondary metabolism were differentially expressed, and the expression levels of 14 genes in aflatoxins synthesis gene cluster that positively regulate aflatoxins synthesis all showed down-trends, and 2 genes (aflC and aflG) that negatively regulate aflatoxins synthesis showed up-trends. We hypothesize that the A. alstroemeriae F1 may secrete some secondary metabolites to inhibit the growth of A. flavus and decrease aflatoxins biosynthesis to a certain extent by regulating the expression levels of genes in aflatoxins biosynthesis gene cluster. In summary, this work lays a foundation for more effective biological controls against A. flavus growth and aflatoxins biosynthesis.