Hydrophobin Gene Cmhyd4 Negatively Regulates Fruiting Body Development in Edible Fungi Cordyceps militaris

A deep understanding of the mechanism of fruiting body development is important for mushroom breeding and cultivation. Hydrophobins, small proteins exclusively secreted by fungi, have been proven to regulate the fruiting body development in many macro fungi. In this study, the hydrophobin gene was revealed to negatively regulate the fruiting body development in , a famous edible and medicinal mushroom. Neither the overexpression nor the deletion of affected the mycelial growth rate, the hydrophobicity of the mycelia and conidia, or the conidial virulence on silkworm pupae. There was also no difference between the micromorphology of the hyphae and conidia in WT and Δ strains observed by SEM. However, the Δ strain showed thicker aerial mycelia in darkness and quicker growth rates under abiotic stress than the WT strain. The deletion of could promote conidia production and increase the contents of carotenoid and adenosine. The biological efficiency of the fruiting body was remarkably increased in the Δ strain compared with the WT strain by improving the fruiting body density, not the height. It was indicated that played a negative role in fruiting body development. These results revealed that the diverse negative roles and regulatory effects of were totally different from those of in and provided insights into the developmental regulatory mechanism of and candidate genes for strain breeding.