油菜根际内生真菌PI-020的分离鉴定和定殖促生作用

Isolation and identification of endophytic fungus PI-020 from root of rape and its promoting and colonization effect

为挖掘农业微生物资源,分离筛选具有促进植物生长作用的内生菌,采用选择性培养基,通过组织分离法自油菜根系皮层组织分离共生真菌,再以无菌油菜苗根际定殖筛选、纯化,获得油菜根际内生真菌PI-020。通过培养形态学观察和转录延伸因子Tef-1α基因序列分析,明确PI-020为梨形孢属(Piriformospora)真菌,与已鉴定种印度梨形孢(P.indica)同源性达98.87%。分离菌株PI-020能在油菜、辣椒、西瓜、水稻等不同植物幼苗皮层细胞定殖,根际皮层附有典型的梨形厚垣孢子,用特异引物进行PCR扩增,获得梨形孢属特有的84 bp基因片段。PI-020在油菜苗根际定殖可显著促进油菜苗生长,表现出油菜株高增加,根系增长,叶面积增大,叶绿素含量显著提高。800、400倍不同浓度PI-020培养液处理15 d后,油菜苗生长量较对照分别提高70.1%和92.7%。这一研究表明分离的梨形孢PI-020是一株对油菜具有定殖促生功能的内生真菌。

From the initial isolation of endophytic fungi at the root cortical tissues of rapes by the method of tissue isolation on selective medium,the strain of PI-020 was screened by re-colonization on the root of rape seedling.Based on morphological features cultured on PDA and analysis of the sequences of Tef-1αgene,the strain of PI-020 was identified to the genus of Piriformospora,which shared the homology by 98.87% to that of the species of P.indica.The PI-020,which was cultured in the medium of PDA,was able to colonize to the cortical cells of different seedlings of rape,pepper,watermelon,and rice,with typical pear-sharped chlamydospores on root surfaces.A special sequence of 84 bp fragment to Piriformospora was also amplified through PCR in the roots of different treatments.PI-020 promoted the growth of rape seedlings significantly,with stem length promoted,root length prolonged,leaf area expended,and chlorophyll content increased.Different concentrations of PI-020 made the weight of rape seedlings increasing about 65.3% to 92.7% comparing to that of control 15 days after treatment.It was indicated that the isolated Piriformospora strain of PI-020 was an endophytic fungus,which performed symbiosis and growth promoting to rape.