一株生防内生真菌的分离筛选、鉴定及抑菌特性

Isolation,screening and identification of an endophytic fungus and the detection of its antifungal effects

为获取优良植物病害生防菌,以交链孢菌Alternaria tenuis Ness和尖镰孢菌Fusarium oxysporum Schlecht为指示菌,采用平板对峙培养法、抑菌圈法和菌落直径法对健康龙柏鳞叶小枝中分离的4株优势内生真菌进行了筛选评价,并结合形态学观察及ITS序列分析对筛选出的生防内生真菌进行了鉴定。结果表明,对峙培养发现1菌株对交链孢菌和尖镰孢菌均具有较好的抑制作用,抑菌率分别为52.05%和48.65%,标记其为LB-1;LB-1菌株与指示菌对峙培养的菌落交界面处,2种指示菌的菌丝均出现了消解、断裂,而LB-1的菌丝则生长正常。未灭菌LB-1菌株发酵液对交链孢菌和尖镰孢菌产生的抑菌圈直径分别为14.1 mm和13.7 mm,抑菌率分别为47.89%和48.72%;灭菌LB-1菌株发酵液对交链孢菌和尖镰孢菌的抑菌圈直径分别为15.3 mm和15.0 mm,抑菌率分别为5.96%和33.90%,指示菌在生长过程中菌丝溶解现象明显。经鉴定,LB-1菌株为毛壳菌属Chaetomium中的近缘毛壳菌C.subaffine,是一种极具生防潜力的内生真菌,其抑菌特性可能通过溶菌作用实现。

To obtain biocontrol fungus for plant diseases, the antifungal effects of four strains of endophytic fungi isolated from leaves of Sabina chinensis cv. Kaizuka were screened and evaluated by using dual-culture,inhibition zone assay and colony diameter assay methods with Alternaria tenuis Ness and Fusarium oxysporum Schlecht as the indicator fungi,and the taxonomic assignment of the screened strain was identified based on the morphological characters and ITS sequence analysis. The results of dual-culture showed that one of the endophytes marked as LB-1 had good antifungal effects and the inhibitory rates of LB-1 strain to A. tenuis and F. oxysporum were 52. 05% and 48. 65%,respectively.The hyphae of the two indicator fungi at the interwoven surface between LB-1 strain and the two indicator fungi collapsed and fractured on dual-cultured PDA plate,while the hyphae of LB-1 strain remained normal. The inhibition zones of A. tenuis and F. oxysporum on non-sterilized LB-1 strain fermentation broth containing PDA plates were 14. 1 mm and 13. 7 mm,respectively,and the inhibitory rates were47. 89% and 48. 72%,respectively. On sterilized LB-1 strain fermentation broth containing PDA plates,the inhibition zone were 15. 3 mm and 15. 0 mm,and the suppression rates were 5. 96% and 33. 90%,respectively. Obvious dissolution of hyphae was observed on sterilized LB-1 strain fermentation broth containing PDA plates. Strain LB-1 was identified as Chaetomium subaffine,which could be a potential biocontrol fungus against plant pathogenic fungi through hyphal dissolving.