MrXrn1基因参与调控罗伯茨绿僵菌的产孢和致病

本研究以罗伯茨绿僵菌为研究对象，针对5'-3'核糖核酸外切酶基因（MrXrn1，MAA_09154，5'-3'exoribonuclease 1），利用农杆菌介导的同源重组方法进行基因敲除。对获得的MrXrn1基因敲除株（ΔMrXrn1）与野生型进行表型分析结果发现，与野生型相比，ΔMrXrn1的营养生长无明显变化，而产孢能力显著下降，其中产孢量降低了75.75%；以大蜡螟为试虫的体壁侵染毒力分析显示ΔMrXrn1的毒力显著减少，也即半致死时间（LT₅₀：9.16 d）显著长于野生型的（5.96 d），但注射接种情况下不同菌株的毒力无差异；进一步的研究表明ΔMrXrn1的附着孢形成率降低了43.58%。这些结果说明MrXrn1基因对绿僵菌的产孢及毒力起着重要的调控作用。本研究为进一步有效提高真菌杀虫剂的生防效果提供了基础。

MrXrn1 Involved in the Regulation of Conidiation and Pathogenicity in Metarhizium robertsii

In the present study, functional analysis for the gene of MrXrn1 (5'-3' exoribonuclease, MAA_09154) was performed by using gene deletion (based on homologous recombination) and phenotypic analysis in Metarhizium robertsii. Our results showed that the conidial yields of ΔMrXrn1 were significantly decreased by 75.75%, compared to the wild-type (WT). More importantly, the results of bioassay showed reduced virulence for the ΔMrXrn1 mutants against Galleria mellonella through cuticle infection, the LT₅₀ of ΔMrXrn1 against G. mellonella was markedly longer than that of the WT. However, different fungal strains exhibited similar virulence in the direction injection bioassays. Furthermore, the results of appressorium formation assays showed that the induced appressorium formation rates were markedly decreased by 43.58% for the deletion mutants, compared with the WT. These results indicated that MrXrn1 is involved in the regulation of sporulation and virulence in M. robertsii. Our research provided a basis for improving the biocontrol effect of fungal insecticides.