Identification, Pathogenicity, and Genetic Diversity of spp. Associated with Maize Sheath Rot in Heilongjiang Province, China.

Maize sheath rot is a prevalent maize disease in China. From 2020 to 2021, symptomatic samples were collected from the main maize-growing regions of Heilongjiang province. To clarify the population and genetic diversity, as well as the virulence of pathogens responsible for maize sheath rot, a total of 132 isolates were obtained and used for follow-up studies. Ten species were identified based on morphological characteristics, and phylogenetic analysis was conducted using the TEF-1α gene sequences, including (50.00%), (18.94%), the species complex (14.39%), (5.30%), (3.03%), (2.27%), (2.27%), (1.52%), (1.52%), and (0.76%). All 10 species could produce oval-to-annular lesions on maize sheath, and the lesions were grayish yellow to dark brown in the center and surrounded by a dark gray-to-dark brown halo. Of these, and showed significantly higher virulence than the other species. In addition, haplotype analysis based on the concatenated sequences of the ITS and TEF-1a genes showed that 99 isolates which belonged to the species complex-consisting of isolates, isolates, isolates, and isolates-could be grouped into 10 haplotypes, including 5 shared haplotypes (Haps 1, 2, 4, 5, and 6) and 5 private haplotypes (Haps 3, 7, 8, 9, and 10). Furthermore, the clade in the haplotype network was radial with the center of Hap 2, suggesting that population expansion occurred. This research showed that species associated with maize sheath rot in Heilongjiang province are more diverse than previously reported, and this is the first time that , , , , , and have been confirmed as the causal agents of maize sheath rot in Heilongjiang province.