The Early Stages in the Interaction Between Mycorrhizal Fungi and Plants

9630842 Hirsch紫花苜蓿根瘤菌-紫花苜蓿共生导致了一种新的结构--大气中氮被还原为氨的根瘤的形成--已经得到了很好的研究。另一方面，使植物能够在缺磷土壤中生长的菌根共生，研究得较少。植物和细菌产生的化学信号参与了这两种生物之间的相互作用。赫希博士和她的同事们已经确定，VAM真菌在菌根中诱导至少两个植物基因的表达，这通常是通过接种根瘤菌来触发的。将研究紫花苜蓿对VAM真菌的早期反应。将真菌的孢子接种到根部，跟踪真菌菌丝侵染的进程，并分析选定的植物基因的表达时间和模式。该奖项支持将这些早期根瘤蛋白基因的表达作为开发生物测定的分子指标的可行性，以检测假定的Myc因子，即诱导VA菌根中特定植物基因表达的化学信号，并参与建立这种重要的共生关系。

9630842 Hirsch The Sinorhizobium meliloti-alfalfa symbiosis, which leads to the formation of novel structure--the root nodule in which atmospheric nitrogen is reduced to ammonia--has been well studied. On the other hand, the mycorrhizal symbiosis, which enables plants to grow in phosphorous-deficient soil, is less well studied. Chemical signals produced by both the plant and the bacterium are involved in establishing the interaction between the two organisms. Dr. Hirsch and her colleagues have determined that VAM-fungi induce the expression of at least two plant genes in mycorrhizal roots that are usually triggered by inoculation with rhizobia. Alfalfa plants will be studied for their early responses to the VAM fungi. The roots will be inoculated with the spores of the fungi, the progress of infection by fungal hyphae will be followed, and the timing and patterns of expression of selected plant genes will be analyzed. This award supports feasibility of using the expression of these early nodulin genes as molecular indicators for developing a bioassay to detect a putative Myc factor, i.e., a chemical signal that induces the expression of specific plant genes in VA-mycorrhizal roots, and is involved in establishing this important symbiosis.