Uncovering the Infection Strategy of During Maize Colonization: A Comprehensive Analysis.

Tar spot, a disease caused by the ascomycete fungal pathogen , is considered one of the most significant yield-limiting diseases of maize () within the United States. may also be found in association with other fungi, forming a disease complex that is thought to result in the characteristic fisheye lesions. Understanding how colonizes maize leaf cells is essential for developing effective disease control strategies. Here, we used histological approaches to elucidate how infects and multiplies within susceptible maize leaves. We collected tar spot-infected maize leaf samples from four different fields in northern Indiana at three different time points during the growing season. Samples were chemically fixed and paraffin-embedded for high-resolution light and scanning electron microscopy. We observed a consistent pattern of disease progression in independent leaf samples collected across different geographical regions. Each stroma contained a central pycnidium that produced asexual spores. Perithecia with sexual spores developed in the stomatal chambers adjacent to the pycnidium, and a cap of spores formed over the stroma. reproductive structures formed around but not within the vasculature. We observed associated with two additional fungi, one of which is likely a member of the genus; the other is an unknown fungi. Our data provide fundamental insights into how this pathogen colonizes and spreads within maize leaves. This knowledge can inform new approaches to managing tar spot, which could help mitigate the significant economic losses caused by this disease.