Cladosporium species causing leaf spot on silage maize based on multi‐locus phylogeny in China

Abstract

AbstractQinghai Province is one of China's five major pastoral areas located in the northeastern part of the Qinghai‐Tibet Plateau, and animal husbandry plays a great part in the local economy. One of the most important crops in Qinghai Province is maize for silage, which sustains ecological animal husbandry. However, the leaf spot disease of maize has seriously impeded the healthy development of the maize industry. We found that from 2019 to 2020 leaf spot of silage maize caused by Cladosporium was a common disease in Qinghai Province. This leaf spot disease formed water‐soaked round or irregular spots at the early stage and gradually expanded to black at the later stage, and the incidence of the leaf spot in the fields reached 15%–45%. In this study, 125 isolates were isolated from seven locations in Qinghai Province, with 123 isolated from leaves and two isolated from bracts of maize for silage. Their phylogeny, morphology, and pathogenicity were analysed to identify pathogens and investigate the differences among them. Based on phylogenetic analysis of multi‐locus (ITS, actin, and translation elongation factor (1‐α)) sequences and morphology characteristics, the 125 isolates were identified to belong to eight species of Cladosporium: C. allicinum, C. cladosporioides, C. xylophilum, C. herbarum, C. macrocarpum, C. asperulatum, C. subinflatum, and C. floccosum. Pathogenicity tests by artificial inoculation demonstrated that 125 isolates were pathogenic on eight maize cultivars for silage, and pathogenicity differentiation was not observed. Taken together, our results demonstrated that these eight species of Cladosporium caused leaf spot disease of maize in Qinghai Province. This is the first analysis report on Cladosporium species from maize in China, and our findings provide a theoretical foundation for the management of this disease in the future.