Necrotrophic effector that plays a critical role during fungal penetration, via its interaction with the host Snn1 protein (PubMed:18943793, PubMed:20084492, PubMed:22241993, PubMed:26217355, PubMed:26416667, PubMed:27041151, PubMed:27133896, PubMed:27819043, PubMed:30858234). Snn1 is a member of the wall-associated kinase class of receptors, which are known to drive pathways for biotrophic pathogen resistance (PubMed:27819043). Recognition of Tox1 by Snn1 induces mitogen-activated protein kinase genes such as MAPK3 and activates programmed cell death, which allows this necrotroph to gain nutrients and sporulate (PubMed:27041151, PubMed:27819043). Recognition of Tox1 by Snn1 also induces other plant defense responses, including oxidative burst and pathogenesis related (PR) gene expression (PubMed:22241993). The development of necrosis and disease induced by Tox1, and particularly penetration during infection, requires light, which is probably related to the light-dependent expression of host Snn1 (PubMed:22241993, PubMed:27819043). Tox1 plays an additional role in providing significant protection from wheat chitinases by binding chitin in the fungal cell wall (PubMed:27041151). Interacts with host cell wall-associated kinase receptor Snn1. Localizes to the outside of mycelium and the penetration structure (PubMed:27041151). Remains largely on the leaf surface during mesophyll necrosis (PubMed:27041151). Expression is induced in planta during disease development and peaks at 3 days post-inoculation correlating with the onset of necrotic lesion development (PubMed:22241993). Expression is increased in the absence of toxin A (ToxA) (PubMed:30858234). Impairs pathogenicity on differential wheat lines harboring the Snn1 gene. The host Snn1 gene confers susceptibility to strains of the necrotrophic pathogen Parastagonospora nodorum that produce the Tox1 protein.