Rhf1 gene is involved in the fruiting body production of Cordyceps militaris fungus.

Cordyceps militaris is an important medicinal fungus. Commercialization of this fungus needs to improve the fruiting body production by molecular engineering. An improved Agrobacterium tumefaciens-mediated transformation (ATMT) method was used to select an insertional mutant (g38) which exhibited fast stromatal differentiation and increased yield. The Rhf1 gene encoding filamentation protein was destroyed by a single T-DNA and no Rhf1 transcription was detected in mutant g38. To verify the function of the Rhf1 gene, RNA interference plasmid and overexpression vector of the Rhf1 gene were constructed and transferred to the wild-type JM4 by ATMT. Fast stromatal differentiation and larger fruiting bodies were found in the RNAi-Rhf1 mutants (JM-iRhf1). In the overexpression mutants (JM-OERhf1), neither stromata nor fruiting bodies appeared. The rescued strain (38-OERhf1) showed similar growth characteristics as JM4. These results indicated that the Rhf1 gene was involved in the stromatal differentiation and the shape formation of fruiting bodies.