Taxonomic Studies Of Epichlo(?) Endophytic Fungi In Chinese Grasses

Endophytic fungi involving in many kinds of plants complete their part or whole lifecycle within plants, without causing any obvious symptom. Most endophytic fungus—grass associations are mutualistic, and the co-evloved symbiosis form complicated interreactions with surrounding environment. Because Epichloe|¨ (Fr.) Tul. species and their anamorph state, Neotyphodium Glenn, Bacon & Hanlin species can mediate many benefits for their host plants, they have been investigated recently in many countries.Epichloe|¨ species as plant endophytes are biotrophic symbionts of many cool-season grasses. To date, six European species and four North American species in Epichloe|¨ genus have been described, without species reported in Asian. In this study, we found abundant Roegneria population infected by Epichloe|¨ endophytes in the middle and lower basin of Yangtze River. From these plants 77 fungal isolates were obtained, and based on morphological characters, host specificity, interfertility tests and molecular phylogenetic evidences we studied the taxonomy of these fungal isolates.Firstly, field surveys were carried in 5 provinces (Jiangsu, Zhejiang, Anhui, Hubei and Hunan) in the middle and lower basin of Yangtze River. From 18 sites in 7 cities, abundant Roegneria population infected by Epichloe|¨ endophytes were found. In early stage, the conidial stroma somewhat waxy, white, and then gradually turning yellow to orange; perithecia pyriform, with short paller necks, 205-275 μm high, 90-140 μm wide; asci (189-252)× (5.0-5.3) μm, containing eight ascospores; ascospores filamentous, (183-250) ×(1.9-2.1)μm, hyaline, non-disarticulating. All of these are typical morphological characters of Epichloe|¨ endophytes. This result indicated that the Roegneria-Epichloe|¨ symbionts were stable host-endophyte associations in the nature, suggesting the widespread of this associations.Secondly, from these Roegneria plants 75 fungal isolates were obtained: On PDA plates, colony diam 20—79 mm in diam after 21 d at 25 ℃, white, cottony, smooth or slightly rough, the growth rate very or moderately slow variable with different sampling sites; aerial mycelium smooth; colony reverses pale brown and lighter toward the margins. Conidiogenous cells discrete, arising solitary from the aerial mycelium, septated at the base,...