一株木榄内生真菌菌株的分类鉴定及其对铁皮石斛生长和多糖积累的影响

Identification of an endophytic fungus isolated from Bruguiera gymnorrhiza and its effects on the growth and polysaccharide accumulation of Dendrobium officinale

【目的】从红树植物内生真菌中筛选能促进铁皮石斛(Dendrobium officinale)生长的内生真菌菌株,并对其进行分类鉴定,为下一步开展铁皮石斛乃至其他特色作物专用菌剂(肥)开发利用提供理论依据。【方法】以北部湾红树植物内生真菌为研究对象,通过平皿和盆栽试验筛选对铁皮石斛具有优良促生作用的菌株,并综合形态学特征观察及ITS序列和18S rDNA序列分析结果对表现突出的促生菌株进行分类鉴定。【结果】从32株内生真菌中筛选获得对铁皮石斛具有良好促生效果的深色有隔内生真菌(DSE)菌株1株,该菌株分离自木榄(Bruguiera gymnorrhiza)茎,编号HS40;通过再分离及显微观察,发现菌株HS40可定殖于铁皮石斛根部并产生DSE的典型特征--微菌核和菌丝。盆栽铁皮石斛苗接种菌株HS40 6个月后,其株高、分蘖数、总鲜重、总干重和茎干多糖含量分别较对照增加21.7%、375.0%、94.7%、57.6%和15.8%,其中,株高、总鲜重、总干重和茎干多糖含量与对照相比达极显著差异水平(P<0.01),分蘖数达显著差异水平(P<0.05)。综合形态观察和序列分析结果,将菌株HS40鉴定为球腔菌科(Mycosphaerellaceae)的Zasmidium citri-griseum。【结论】菌株HS40可显著促进铁皮石斛的生长并提高其茎干多糖含量,有望用于开发铁皮石斛专用菌剂(肥)。

【Objective】To select and identify endophytic fungus isolates from mangrove which could promote the growth of Dendrobium officinale,aiming to provide functional isolates and theoretical basis for the development of microbial inoculum or bacterial manure for D. officinale and even other special crops.【Method】The endophytic fungi,isolated from mangrove plants in Beibu Gulf,were inoculated to D. officinale,growing both in Petri dishes and plastic cups,to evaluate their growth promoting capacity,and the fungi with good performance were identified based on morphological characteristics and sequences analysis of ITS and 18S rDNA gene.【Result】An isolate of dark septate endophytes(DSE)having sound promotion effects on D. officinale,with the number of HS40 and being isolated from stem of D. officinale,was screened out from 32 endophytic fungi. The results showed that,HS40 could colonize in the roots of D. officinale,and the microsclerotium,typical characteristic of DSE,could be found in the root re-isolation and microexamination. Compared to that of non-inoculated plants(CK),the average plant height,number of new buds,total fresh weight,total dry weight and polysaccharide content in stems of the plants inoculated by HS40 after growing in the plastic cups for 6 months increased significantly by 21.7%,375.0%,94.7%,57.6% and 15.8%,respectively. The difference compared to control of plant height,total fresh weight,total dry weight and polysaccharide content reached extremely significant level(P<0.01),and that of number of new buds reached significant level(P<0.05). Based on morphological observation and sequence analysis mentioned above,isolate HS40 was identified as Zasmidium citri-griseum,which belonged to the family of Mycosphaerellaceae.【Conclusion】Isolate HS40 can significantly promote D. officinale growth and improve polysaccharide content in its stems,thus,it might be further used in the production of microbial inoculum or bacterial manure for D. officinale.