云南元江印楝植物内生真菌的种类组成

Composition of endophytic fungi in Azadirachta indica from Yuanjiang County of Yunnan

为了探悉内生真菌在植物体内的多样性,从中寻找新的具有生物活性的微生物资源,我们研究了云南元江4个不同地理种源印楝(Azadirachta indica)内生真菌的种类组成、数量及分布规律。从印楝植物茎和果实中共分离到372株内生真菌,分属于50属,分布最广的类群是刺盘孢菌属(Colletotrichum),占总菌株的25.54%;其次是交链孢属(Alternaria)(11.56%)和炭角菌属(Xylaria)(7.80%)。各组织获得菌株数量比例最大的分别为ka种源茎部(19.89%)、ck种源茎部(19.62%)和ma种源茎部(18.82%);最小的为ka种源果实部(5.11%)和ku种源果实部(6.18%)。丰富度最大的为ma种源(包含29属),最小的为ku种源(23属)。印楝植物茎部分离到的菌株类群和数量明显多于果实。不同地理种源印楝植物内生真菌的种类组成没有明显差异,但是有的内生真菌表现出一定的宿主或组织专一性。印楝植物丰富的内生真菌资源可能成为产生具有生物活性次生代谢产物的重要来源,尤其是与宿主植物相关的印楝素类四降三萜化合物。

In order to explore the endophytic fungi diversity in Azadirachta indica and discover new species and bioactive strains, we studied the composition, quantity, and distribution of endophytic fungi in A. indica from Yuanjiang County of Yunnan, which had been introduced from four different germplasm sources of India （ma, ku, ka and ck）. A total of 372 endophytic fungi strains were isolated from the stem and fruits of A. indica. Of these, Colletotrichum （25.54%） was the most prevalent genus, followed by Alternaria （11.56%） andXylaria （7.80%）. The most dominant fungi appeared in the stems from ka （19.89%）, ck （19.62%） and ma （18.82%）, while the least appeared in the fruits from ka （5.11%） and ku （6.18%）. The fungi from ma had the highest richness （29 genera） whereas those from ku had the lowest （23 genera）. More species and strains were isolated from the stems than from the fruits. Species composition of endophytic fungi showed no significant difference among different germplasm sources. Some endophytic fungi were host- and tissue-specific. Rich endophytic fungi in A. indica may be an important source ofbioactive secondary metabolites, especially the azadirachtins and related tetranortriterpenoids associated with the host plant.