1株内生真菌的分离鉴定及其对铁皮石斛的促生作用
Isolation and identification of endophytic fungus Devriesia lagerstroem and its promoting effect on Dendrobium candidum growth

从不同植物的茎和叶中分离获得204株真菌，通过对白菜的致病性测定筛选获得1株能显著促进白菜生长的内生真菌菌株24L-4。结合形态学特征观察进行ITS-rDNA和18S-rDNA序列分析，对其进行鉴定，确定为Devriesia lagerstroem。该菌株对铁皮石斛组培苗的株高、叶宽、茎径和干质量分别较未接种对照处理增加33.3%、65.7%、27.3%和45.1%，显著高于对照处理。同时，盆栽试验表明：D. lagerstroem铁皮石斛盆栽苗的茎径、鲜质量和干质量分别较无接种对照增加104.0%、83.9%和114.7%，显著高于对照处理。显微镜观察发现：D. lagerstroem可定殖于铁皮石斛根部的外皮层和皮层。研究结果表明，D. lagerstroem对铁皮石斛具有明显的促生作用，可用于铁皮石斛菌肥的开发。
Two hundred and four fungal isolates were obtained from stems and leaves of different plants.One endophytic fungal isolate 24L-4 was selected by pathogenicity test on Chinese cabbage.Isolate 24L-4 was identified as Devriesia lagerstroem based on its morphological characteristics and sequences of internal transcribed spacer and 18S ribosomal DNA.Isolate 24L-4 was inoculated on Dendrobium candidum tissue cultures and pot seedlings,respectively,with non-inoculated seedlings as the control.The results showed that the seedling height，leaf width，stem diameter and dry weigh were significantly enhanced by 33.3%，65.7%，27.3% and 45.1%,respectively,in the tissue cultures.Similar results were observed in the pot experiment with increase percentages by 104.0%，83.9% and 114.7% for the stem diameter，fresh weight and dry weight,respectively.The hyphae and microscierotia-like structures of isolate 24L-4 were found in the root epidermal and cortex of D. candidum.These results indicated that isolate 24L-4 had excellent growth promoting effect on D. candidum.