中文摘要：

内生菌对于植物的健康和新陈代谢具有非常重要的作用,目前内生菌对芳香植物香茅草挥发性有机化合物（VOCs）代谢的影响尚不清楚。试验分离了不同生长季节的香茅草内生细菌,得到1株具有清新自然香味的优势内生菌CcLf-2,鉴定为芽孢杆菌属。通过顶空气相色谱质谱联用仪对香茅草VOCs进行检测,发现不同季节其主要挥发性物质柠檬醛含量的变化与CcLf-2的分离率分布规律一致。进一步将CcLf-2接种到香茅草无菌苗中,发现CcLf-2可以成功定殖到香茅草中,并明显增强其所产柠檬醛的比例。实时定量PCR（qRT-PCR）分析表明,CcLf-2的存在可诱导香茅草中柠檬醛生物合成途径相关基因的表达量显著上升（P〈0.05）。说明内生菌可以作为诱导子来提高宿主植物中一些重要的VOCs的产量。

英文摘要：

The exislence of endophytes significanlly contributes to plant health and metabolism, however, the effects of endophytes on the volatile organic compounds （VOCs） metabolism of aromatic plant Cymbopogon citragus are still unclear. In this study, the endo- phylic bacleria from C. citrazus grown at different seasons were iso- lated, and a dominant endophytic bacterium Bacillus sp. Ccl.f 2 was identified, with a fragrance-producing property. After seasonal analy sis of the VOCs of C. cilragus by headspace gas chromatography mass speclromclry, found thai the abundance pattern of CcI.f 2 had a similar trend with the emission profile of citral, the primary and valuable composition of VOCs, in C. citratus. By inoculating Cel.f-2 into C. citralus ascplic seedlings obtained by tissue culture, cndo- phyte reisolation lest verified the colonization of Ccl.f 2 in plants and the presence of Ccl＋f-2, which can increased the cil ral propottion, obviously. Moreover, quantitative real＋time PCR analysis of relevant genes in the citral biosynthesis pathway revealed than they were significantly up regulated （at least P 〈0.05） with the existence of Cel.f 2. The endophylic bacteria may enhance the eitral production by modulating the expression of genes related to biosynthesis. And implies lhe possibility of using endophytic bacteria as a regulator to improving yields of some important VOCs in its host.