Members of the fungal genus (Ascomycota, Hypocreales, Hypocreaceae) are ubiquitous and commonly encountered as soil inhabitants, plant symbionts, saprotrophs, and mycoparasites. Certain species have been used to control diverse plant diseases and mitigate negative growth conditions. The versatility of 's interactions mainly relies on their ability to engage in inter- and cross-kingdom interactions. Although is by far the most extensively studied fungal biocontrol agent (BCA), with a few species already having been commercialized as bio-pesticides or bio-fertilizers, their wide application has been hampered by an unpredictable efficacy under field conditions. Deciphering the dialogues within and across ecological interactions by identification of involved effectors and their underlying effect is of great value in order to be able to eventually harness 's full potential for plant growth promotion and protection. In this review, we focus on the nature of interactions with plants and pathogens. Better understanding how interacts with plants, other microorganisms, and the environment is essential for developing and deploying -based strategies that increase crop production and protection.