科研之友
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<jats:title>ABSTRACT</jats:title><jats:p>Caleosins are a small family of calcium-binding proteins endowed with peroxygenase activity in plants. Caleosin-like genes are present in fungi; however, their functions have not been reported yet. In this work, we identify a plant caleosin-like protein in<jats:named-content content-type="genus-species">Aspergillus flavus</jats:named-content>that is highly expressed during the early stages of spore germination. A recombinant purified 32-kDa caleosin-like protein supported peroxygenase activities, including co-oxidation reactions and reduction of polyunsaturated fatty acid hydroperoxides. Deletion of the caleosin gene prevented fungal development. Alternatively, silencing of the gene led to the increased accumulation of endogenous polyunsaturated fatty acid hydroperoxides and antioxidant activities but to a reduction of fungal growth and conidium formation. Two key genes of the aflatoxin biosynthesis pathway,<jats:italic>aflR</jats:italic>and<jats:italic>aflD</jats:italic>, were downregulated in the strains in which<jats:named-content content-type="genus-species">A. flavus</jats:named-content><jats:italic>PXG</jats:italic>(<jats:italic>AfPXG</jats:italic>) was silenced, leading to reduced aflatoxin B1 production<jats:italic>in vitro</jats:italic>. Application of caleosin/peroxygenase-derived oxylipins restored the wild-type phenotype in the strains in which<jats:italic>AfPXG</jats:italic>was silenced.<jats:italic>PXG</jats:italic>-deficient<jats:named-content content-type="genus-species">A. flavus</jats:named-content>strains were severely compromised in their capacity to infect maize seeds and to produce aflatoxin. Our results uncover a new branch of the fungal oxylipin pathway and may lead to the development of novel targets for controlling fungal disease.</jats:p>
- 出版日期2015-9
