Sarocladium within plant hosts: from beneficial endophyte to necrotrophic pathogen

The genus Sarocladium (order Hypocreales) comprises filamentous fungi engaging in diverse interactions with plants. While many species of this genus function as endophytes, some are also capable of causing diseases such as the infamous rice sheath rot. In this review, we synthesize current knowledge on these contrasting plant-associated lifestyles. Metabarcoding studies indicate that Sarocladium species are widespread, occurring predominantly in soil, air, and plant samples from vegetated biomes. These fungi behave as free-living saprobes and endosymbionts of plants, primarily—though not exclusively—of poaceous grasses. Notably, several of these species share biological characteristics with Class 2 endophytes, a diverse polyphyletic group with extensive transmission and colonization abilities, often associated with stress tolerance. We argue that necrotrophic traits, which appear largely opportunistic within Sarocladium , have sporadically emerged in several endophytic (sub)species; their origins and manifestation are examined herein. Finally, we propose future research avenues focusing on neglected metabolomics, genomics, and ecological aspects of the genus.