REGULATION OF PLANT GENES INVOLVED IN MODULATION OF NH3 ASSIMILATION

大多数具有重要营养意义的生物固氮作用是 由根瘤菌/缓慢根瘤菌执行，这是一种只固定氮素的细菌 在根瘤内，它们形成于豆科植物的根部。我们的长期目标 是提高定植效率，扩大寄主范围至 非豆科植物。这里提出的研究是为了理解最初的 寄主和共生体之间的相互作用以及植物如何利用 还原的氮气。该建议主要集中在两个方面：(I) 确定类黄酮在根瘤形成中的作用；(Ii)确定 如果氨同化能得到改善，这是否会产生影响 关于工厂的整体氮素状况。在我们项目的第一部分， 重点放在编码苯丙烷类化合物关键酶的基因上。 类黄酮合成途径--苯丙氨酸解氨酶 (PAL)、查尔酮合酶(CHS)和查尔酮异构酶(CHI)。这项研究 包括研究对家庭中不同成员的监管 以及关键成员的过表达/过低表达对根瘤形成的影响。 谷氨酰胺合成酶(GS)是氨同化的关键酶。 这是我们理解氨同化的核心，也是 第二部分。我们的研究结合了分子和生物化学 理解功能角色和调节机制的方法 不同GS基因成员的潜在表达。此外， 不同GS基因成员下调和上调对细胞周期的影响 氨同化和固氮的效率正在研究中。 旨在提高豆类营养质量的第二个项目 种子和饲料，这是正在实验室中进行的，是引入到 这些植物高表达编码高硫氨基酸的基因 蛋白质。 总之，实验室中的项目利用了最先进的技术 分子生物学、生物化学和细胞生物学 对人类营养有直接影响的植物生物学问题。

Most of the nutritionally significant biological nitrogen fixation is carried out by Rhizobia/Bradyrhizobia, bacteria that fix nitrogen only within the nodules they form on the roots of legumes. Our long-term goal is to improve the efficiency of fixation and to broaden the host range to nonlegumes. The research proposed here is to understand the initial interaction between the host an the symbiont and how the plant utilizes the reduced nitrogen. The proposal focuses on two major aspects: (i) to determine the role of flavonoids in nodule initiation; (ii) to determine if ammonia assimilation can be improved and if that would have an impact on the overall N-status of the plant. For the first part of our project, the focus is on genes encoding for key enzymes in the phenylpropanoid pathway leading to flavonoid synthesis - phenylalanine ammonia lyase (PAL), chalcone synthase (CHS) and chalcone isomerase (CHI). The study involves studying the regulation of the different members of the family and the effect of over/under expressing key members, on nodule initiation. Glutamine synthetase (GS), the key enzyme in ammonia assimilation, is central to our understanding of ammonia assimilation and is the theme of the second part. Our research combines a molecular and biochemical approach to understand the functional role and regulatory mechanism underlying expression of different GS gene members. Furthermore, the effect of down and up regulation of different GS gene members on the efficiency of ammonia assimilation and N2-fixation, is being studied. A second project aimed towards improving the nutritional quality of legume seeds and forage, that is being pursued in the lab, is to introduce into these plants highly expressing genes encoding for high sulfur amino acid proteins. Altogether, the projects in the lab utilize state-of-the-art techniques in molecular biology, biochemistry and cell biology to address important issues in plant biology that have a direct impact on human nutrition.