Endophytic fungi and arbuscular mycorrhizal (AM) fungi are important components of grassland ecosystem. Endophytes can reduce colonization rates of their host plants by AM fungi. In this study, Achnatherum sibiricum, infected by Epichlo sibiricum (Es) or E. gansuensis (Eg), was adopted as experimental material. The effect of Epichlo endophyte culture filtrate, root exudates and aqueous extracts from the leaves (including fresh and dead leaves) on the spore germination rates of AM fungi (Glomus mosseae and Glomus etunicatum) were evaluated. The results showed that culture filtration of Epichlo endophyte significantly inhibited the germination rate of AM fungi spores. Root exudates of infected plants only significantly inhibited the germination of G. etunicatum spores, and such effect was not related to the endophytic species. The leaf aqueous extracts had no significant effect on the germination rate of G. mosseae spores. Only the aqueous extract of Es-infected dead leaves significantly reduced the spore germination rate of G. etunicatum. In natural ecosystem, Epichlo endophytes are normally internally hosted in plants, which may affect the spore germination of AM fungi by affecting the root exudates of the host plants.
内生真菌与丛枝菌根(AM)真菌是构成草原生态系统的重要组成部分.内生真菌会抑制其宿主植物的AM真菌侵染率.本研究以感染2种香柱菌属内生真菌[Epichloё gansuensis(Eg)和E. sibirica(Es)]的天然禾草羽茅为供试材料,进行体外纯培养的内生真菌培养滤液、感染内生真菌的羽茅叶片(包括鲜叶和枯叶)浸提液,以及根系分泌物对摩西球囊霉(Gm)和幼套球囊霉(Ge)2种AM真菌孢子萌发影响试验.结果表明: 香柱菌属内生真菌的培养滤液会显著抑制2种AM真菌孢子的萌发,而感染香柱菌属内生真菌的羽茅根系分泌物只对Ge孢子萌发有显著抑制作用,且上述抑制作用与内生真菌种类无关;鲜叶浸提液对Gm和Ge的孢子萌发率均无显著影响,而枯叶浸提液对Ge的孢子萌发有显著抑制作用.在自然生态系统中,香柱菌属内生真菌通常存在于宿主植物体内,可能通过影响宿主植物的根系分泌物来影响AM真菌孢子的萌发.
Keywords: Achnatherum sibiricum; Epichlo endophytes; arbuscular mycorrhizal fungi; extraction; spore germination.