与菌根真菌形成互惠互利的菌根共生体系是植物在长期进化过程中形成的适应土壤有效磷缺乏的最重要的机制之一。我们前期工作表明，茄科植物基因组中存在保守的启动菌根调控表达的顺式作用元件MYCS及可能与之结合的转录因子MYCF1，且MYCS与缺磷信号调控因子PHR的作用元件P1BS共同调控菌根诱导基因的表达。本项目选择烟草为试材，在已克隆MYCF和PHR全长基础上，通过酵母单杂交系统继续筛选与MYCS结合的潜在转录因子基因，并在酵母双杂交体系中研究其与PHR的互作；利用启动子融合GUS报告基因、基因枪轰击洋葱表皮技术分析其组织和亚细胞水平定位情况；通过RNAi敲除和过量表达转基因材料分析鉴定MYCF、PHR及可能存在的其它结合MYCS的转录因子的生物学功能，由基因芯片结合ChIP-qPCR和EMSA技术研究其对菌根响应基因表达的协同调控。本研究有望首次在分子水平上明确植物菌根与磷调控信号的互作机制。

Forming the mutualistic symbiotic associations with arbuscular mycorrhiza fungi is one of the most crucial strategies adopted by plants agaist the Pi-limiting condition in the soil. In our previous work, we identified a novel cis-element (MYCS) and the transcription factors binding to it (MYCF1), which are indispensable for the transcriptional activation of mycorrhiza-induced/specific phosphate transporter genes in tobacco. In addition,we found that the conserved regulatory module for Pi starvation (PHR-P1BS)is also required for this transcriptional activation. In the present study, we intend to isolate other potential transcription factor encoding gene(s) binding to MYCS in tobacco using yeast one-hybrid system, and to investe the potential protein interaction between PHR, MYCF1 and other unknown transcription factor(s). Moreover, tissue and subcellular localization of all the transcription factors will be analyzed by transgenic plants carrying promoter-GUS fusions and bombardment experiment. Furthermore, the biological roles in mycorrhiza symbiosis of MYCF1, PHR, and other MYCS-binding transcription factors will be studied by using their RNAi knockdown and overexpressing lines, and microarray, ChIP-qPCR, and EMSA will be utilized to explore the downstream genes regulated by these transcription factors. Accomplishing this study, we will stand a good chance to elucidate the molecular mechanisms underlying mycorrhiza and phosphate signalings, as well as their potential corss-talk.