Abstract:

Timothy grass（Phleum pretense） is a perennial， tufted grass belonging to the Poaceae family. It is commonly used as a forage crop， and is highly valued for its productivity and high quality as forage. It is a significant source of pasture and income for herders in Min County， Gansu Province， China. However， little is known about the diversity and pathogenicity of seed-borne fungi in timothy grass. In this study， we used a combination of traditional culture-based methods and high-throughput sequencing to investigate the diversity and pathogenicity of seed-borne fungi in timothy grass. Using traditional culture-based methods， 13 fungal species in nine genera were isolated from the three tested Timothy grass varieties. The five most commonly isolated species were Alternaria alternata， Fusarium avenaceum， Lichtheimia corymbifera， Epicoccum nigrum， and Aspergillus chevalieri. High-throughput sequencing revealed the presence of fungi from 27 genera across two phyla， predominantly Ascomycota and Basidiomycota， including genera such as Alternaria， Aspergillus， Phaeosphaeria， and Fusarium. At the species level， the prevalent species were A. alternata， Gibberella avenaceum， Mycosphaerella tassiana， Alternaria metachromatica， and Parastagonospora nodorum， and there were significant differences in the α and β diversity of the seed-borne microbial community among the three tested timothy grass varieties. Eight of the seed-borne fungal isolates significantly reduced the germination rate （by 9.78%-30.67%） and vigor （by 10.69%-32.08%） of timothy grass seeds （P<0.05）. Aspergillus pseudoglaucus resulted in the lowest germination rate of timothy grass seeds， while A. alternata and A. pseudoglaucus significantly increased the mold rate of seeds. The findings of this research provide a theoretical basis for the utilization of timothy grass and the prevention of seed-borne diseases.

Key words: Phleum pratense, seed-borne fungi, diversity, pathogenicity