Plant Genes Expressed Early in Development of Medicago Truncatula Root Nodules

固氮根瘤是根瘤菌与特定豆科寄主植物内共生关系的结果。Cooper博士将利用细胞和分子遗传学方法来研究根瘤发展的早期事件，这些事件发生在melilotim - medicago truncatula共生中。本研究的具体目标是：1)克隆和表征结节发育早期表达的结节蛋白基因，重点关注（羟基）脯氨酸丰富的细胞壁糖蛋白基因；2)在蛋白和核酸水平上研究早期共生基因表达的时空格局；3)利用报告基因融合来鉴定负责观察到的基因表达模式的顺式调控序列，并开始表征根瘤菌调节植物发育所使用的信号分子。这些研究结果将为根瘤发育和植物与微生物相互作用的分子遗传学分析提供新的工具。固氮细菌与亲和性植物根系结合的调节机制既是生物如何相互作用和影响的基础科学问题，也是具有重大农业经济和生态利益的问题。对这种相互作用模式敏感的植物不需要为其生长添加相同的氮肥。

Nitrogen-fixing root nodules result from an endosymbiotic association between Rhizobium bacteria and specific legume host plants. Dr. Cooper will utilize cellular and molecular genetic approaches to investigate early events in the development of root nodules in the Rizobium meliloti-Medicago truncatula symbiosis. The specific goals of this proposal are: 1) to clone and characterize the nodulin genes expressed early in nodule development, with particular attention paid to (hydroxy)proline- rich cell wall glycoprotein genes; 2) to examine the spatial and temporal patterns of early symbiotic gene expression at both the protein and nucleic acid levels; and 3) to use reporter gene fusions to identify the cis-acting regulatory sequences responsible for the observed patterns of gene expression, and to begin characterizing the signal molecules used by Rhizobium to regulate plant development. Results of these studies will provide new tools for the molecular genetic dissection of nodule development and plant-microbe interactions. %%% The mechanisms regulating the association of nitrogen fixing bacteria with the roots of compatible plants is a problem of interest both as a basic science question of how organisms interact and affect each other and a problem with great agricultural economic and ecological interest. Plants which are susceptible to this mode of interaction do not require the same addition of nitrogenous fertilizer for their growth.