SsNEP2 Plays a Role in the Interaction Between Sclerotinia sclerotiorum and Coniothyrium minitans

<i>Sclerotinia sclerotiorum</i>, a fungal pathogen that is spread worldwide and causes serious diseases on crops, can be parasitized specifically by the mycoparasite <i>Coniothyrium minitans</i>. <i>SsNEP2,</i> encoding a necrosis-inducing protein in <i>S. sclerotiorum,</i> was previously inferred to play a role in the virulence to host plants. In this study, silencing of <i>SsNEP2</i> in <i>S. sclerotiorum</i> had no significant (<i>p</i> < 0.01) influence on mycelial morphology, while overexpression led to lower mycelial growth and more branches. When amended with the fermentation broth of the <i>SsNEP2</i> silencing mutants, conidial germination of <i>C. minitans</i> was promoted, while conidial production decreased. When parasitized by <i>C. minitans</i>, enhanced resistance of the <i>SsNEP2</i> silencing mutants and weaker resistance of the overexpressed transformants were observed compared to the wild-type <i>S. sclerotiorum</i> strain 1980. In addition, the expression of <i>SsNEP2</i> in <i>C. minitans</i> enhanced mycelial parasitism on <i>S. sclerotiorum</i> and restored the effect of silencing <i>SsNEP2</i> in <i>S. sclerotiorum</i> on mycoparasitism. Thus, we highlight the role of <i>SsNEP2</i> as a PAMP-like protein in the mycoparasitism between <i>C. minitans</i> and its host fungus <i>S. sclerotiorum. SsNEP2</i> can be used to promote the biological potential of <i>C. minitans</i>.