我国3种疯草的内生真菌培养特性研究

摘要

家畜取食疯草出现中毒或死亡的原因为疯草体内含可产生苦马豆素的内生真菌.我国的多种疯草中的内生真菌为同一种,同种疯草中的内生真菌因随种子传播而孤立于单一寄主,可能出现与其他疯草内生真菌不同的生物学特性.为此在通过形态学和分子生物学鉴定菌种的基础上研究了我国最主要3种疯草小花棘豆、黄花棘豆和甘肃棘豆中内生真菌菌株(LYZ0091、LYZ0093和LYZ0109)在不同温度、pH值和培养基上的菌落生长速率和形态特性.结果表明,1)3个菌株的菌落停止生长的最高温度不同,LYZ0109无法在30℃下生长,但LYZ0091和LYZ0093仍可生长,最适宜生长温度分别为20、25和25℃,在5、10和15℃下4周时LYZ0091的生长速率显著(P＜0.05)高于LYZ0109,在20和25℃下则显著(P＜0.05)低于LYZ0109;2)在pH 4～11下3个菌株均可生长,菌株之间无显著(P＞0.05)差异;在培养基NA、PCA、PDA、PSA和WHDA上LYZ0109多显著(P＜0.05)大于LYZ0091;3)在温度、pH值和培养基处理中3个菌株均未产生分生孢子,LYZ0091和LYZ0109的菌丝扭曲状,厚垣孢子少,而LYZ093无扭曲状菌丝,大量成串的厚垣孢子由基质底部向上呈树状生长.%Locoweeds contain swainsonine-producing fungal endophytes.Endophytes in several locoweed species in China are known to belong to the same taxonomic species of fungus.However,since these endophytes are isolated within their respective hosts and vertically transmitted to seed of the next plant generation,it is likely that the fungal endophytes of the various locoweed species have developed distinctive biological traits.Colony growth rate and morphological characteristics of endophytes from Oxytropis glabra,O.ochrocephala and O.kansuensis (strains LYZ0091,LYZ0093 and LYZ0109,respectively) were studied under different temperature and pH regimes and grown on various media to test this hypothesis.It was found that:1) The maximum temperature for growth differed between strains (LYZ0109 ceased growth at 30 ℃,while LYZ0091 and LYZ0093 continued to grow at 30 ℃);2) The optimum temperatures for colony growth were 20,25 and 25 ℃,respectively,for LYZ0091,LYZ0093,and LYZ0109;3) The growth rate of LYZ0091 at 5,10 and 15 ℃ was significantly (P＜0.05) higher than LYZ0109,while significantly (P＜0.05) lower than LYZ0109 at 20 and 25 ℃.4) No significant growth difference between fungal strains was found over the pH range pH 4 to pH 11;5) The colony growth rate of strain LYZ0109 was significantly (P＜0.05) higher than that of LYZ0091 on NA,PCA,PDA,PSA and WHDA media for most growth measures;6) No conidia were produced by any fungal strain in any of temperature,pH and media combinations tested;7) Hyphae of LYZ0091 and LYZ0109 were waved,and seldom produced chlamydospores;hyphae of LYZ093 were straight with plentiful chlamydospores arranged as tree-like structures from the media bottom to the surface.