Downregulation of pre-rRNA processing gene Mamrd1 decreases growth, conidiation and virulence in the entomopathogenic fungus Metarhizium acridum.

Mrd1 is one of the trans-acting proteins and plays an important role in precursor ribosomal RNA processing. Here we characterized the Mamrd1 gene from Metarhizium acridum and studied its function in growth, conidiation and virulence using RNA interference. The Mamrd1 gene was identified as participating in the processing of pre-rRNA in M. acridum and was highly upregulated during the infection process. A Mamrd1-RNAi strain exhibited an appearance of fluffy mycelia, a defective branching pattern and delayed conidiation compared to the wild-type strain. Downregulation of Mamrd1 in M. acridum suppressed growth both on artificial medium and inside the insect, and significantly reduced hyphal biomass, conidium production and virulence against Locusta migratoria manilensis. These results demonstrated that Mamrd1 plays an important role in growth, conidiation and virulence in M. acridum.