Abstract: Stylosanthes gracilis is a wild relative of S. guianensis，which has some advantages such as stem upright,Low seed shattering and strong drought resistance. In order to develop an efficient transformation system of the hairy root of S. gracilis, this study selected the cotyledonary nodes of S. gracilis as the explants and four strains of Agrobacterium rhizogenes as the test ones to explore the effects of bacterial solution concentration,infection time and co-culture time on the hairy root transformation efficiency. The results showed that the MSU440 was the best strain to induce that hairy roots with an induction rate of 88.3%. Further,OD600 0.3 bacterial solution concentration,15 min infection time and 4 d co-culture time was determined to be the best conditions for the generation of hairy roots induced by that strain,at which the transformation efficiency reached 34.72%. At the same time,the integration of exogenous genes into the genome of the hairy roots of S. gracilis was verified by the both polymerase chain reaction (PCR) and Western Blot detections. As a result,this study already successfully established a hairy root transgenic system of S. gracilis.

Key words: Stylosanthes. gracilis, Cotyledonary node, Agrobacterium rhizogenes, Genetic transformation, Hairy roots

摘要： 细茎柱花草(Stylosanthes gracilis)是圭亚那柱花草(S.guianensis)的野生近缘种，具有茎秆直立、种子落粒性低、抗旱能力较强等特点。为开发一种高效的细茎柱花草毛状根转化体系，本研究以细茎柱花草子叶节为外植体及4个发根农杆菌为供试菌种，探索菌液浓度、侵染时间、共培养时间对毛状根转化效率的影响。结果表明MSU440为诱导毛状根发生的最优菌株，诱导率为88.3%。其中，该菌株诱导毛状根产生的最佳条件为菌液浓度OD600=0.3、侵染时间为15 min、共培养4 d，转化效率达34.72%。同时，获得的转基因材料通过聚合酶链式反应(PCR)和蛋白质免疫印迹(Western blot)分子鉴定方式，证实了外源基因已整合到细茎柱花草毛状根的基因组中。因此，本研究成功建立了一种细茎柱花草的毛状根转基因体系。

关键词: 细茎柱花草, 子叶节, 发根农杆菌, 转基因, 毛状根