Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 5/30/2005
Publication Date: 8/7/2005
Citation: Moon, Y., Krasnoff, S.B., Donzelli, B.G., Vandenberg, J.D., Churchill, A.C., Gibson, D.M. 2005. Targeted disruption of a peptide synthetase gene in metarhizium anisopliae has no effect on destruxins production or virulence against insects. Society for Invertebrate Pathology Annual Meeting. p. 51. Interpretive Summary:
Technical Abstract: The principal toxins produced in fermentation by M. anisopliae are the destruxins, cyclic depsipeptides with chemical features suggesting synthesis by a nonribosomal peptide synthetase (NRPS). We targeted for further study an NRPS gene fragment (ma267) identified by Freimoser et al. (2003) as an EST expressed after 24 hr of fungus growth on insect cuticle-containing medium. Ma267 detects DNA polymorphisms that correlate with relative levels of in vitro destruxins production in 16 M. anisopliae isolates. Additionally, ma267 gene expression is positively correlated with in vitro destruxins production. We disrupted the ma267 gene by Agrobacterium tumefaciens-mediated transformation and identified several stable knockout (KO) transformants. Three KO transformants exhibited normal growth rates and levels of destruxins production comparable to an ectopic transformant and the wild type strain, suggesting that the ma267 gene is not involved in destruxins production. A fourth KO transformant (B1-3) has an additional uncharacterized mutation correlated with overproduction of metabolites not previously reported from Metarhizium. We observed no detectable differences in pathogenicity of the four ma267 KO mutants in bioassays against beet armyworm and Colorado potato beetle. Further studies are required to determine whether the ma267 NRPS plays a role in the biology of M. anisopliae as an insect pathogen.