Molecular Genetics of Ethylene-Auxin Interactions in Arabidopsis

知识价值。激素是协调植物对发育和环境信号反应的关键成分。激素介导的整合过程，虽然在生理水平上已经明确确立，但在分子水平上仍然很大程度上未知。该项目确定并表征了模式植物拟南芥中乙烯反应和生长素生物合成途径之间相互作用的特定点。这些研究的意义超越了激素串扰，扩展到大部分未知的生长素生物合成途径及其调控。三个新的根特异性乙烯抗性突变体（wei2， wei7和wei8）已经被鉴定出来。wei2和wei7的克隆和鉴定揭示了色氨酸生物合成酶蒽甲酸合酶的a和b亚基在生长素生物合成中的调控作用。同样，WEI8的初步表征表明，WEI8蛋白催化色氨酸转化为吲哚-3-丙酮酸，这是生长素生物合成的关键步骤，此前没有遗传信息。WEI8是拟南芥中一个由5个成员组成的多基因小家族。为了进一步剖析WEI8和WEI8样（WEL）基因在生长素生物合成中的作用，了解它们在乙烯中的调控作用，并确定生长素生物合成途径中的其他遗传元件，我们设定了以下特定目标。1)确定WEI8及其最接近的同源物WEL1和WEL2在乙烯反应中的作用。2)确定WEI8、WEL1和WEL2在生长素生物合成中的作用。3)鉴定和鉴定新的wei突变体。更广泛的影响。改变植物对特定激素的反应可用于提高农业生产。由于一种激素在发育过程中具有多种功能，这些操作通常会导致附带的不良影响。因此，了解一种激素如何根据组织、发育和环境条件等产生完全不同的影响，对于智能操纵植物生产至关重要。该项目将提供生长素生物合成遗传学的基础信息，从而使人们能够有效地控制植物中由生长素调节的无数过程。这笔资金的一个重要部分将用于培养基础和应用植物生物学方面的学生和博士后。作为培训的一部分，所有相关人员都将能够参加科学会议，了解其研究领域的最新进展，并分享他们自己的发现。

Intellectual Merit. Hormones are key components in the orchestration of plant responses to developmental and environmental cues. The hormone-mediated integration process, although clearly established at the physiological level, is still largely unknown at the molecular level. This project identifies and characterizes specific points of interaction between the ethylene response and auxin biosynthetic pathway in the model plant Arabidopsis thaliana. The implications of these studies expand beyond the hormone crosstalk to the largely unknown auxin biosynthetic pathway and its regulation.Three new root-specific ethylene resistant mutants have been identified (wei2, wei7, and wei8). Cloning and characterization of wei2 and wei7 uncovered an unexpected role of a and b subunits of a tryptophan biosynthetic enzyme anthranilate synthase in the regulation of auxin biosynthesis. Similarly, initial characterization of WEI8 indicates that the WEI8 protein catalyzes the conversion of tryptophan to indole-3-pyruvic acid, a key step in auxin biosynthesis for which no genetic information was available previously. WEI8 belongs to a small multigenic family of 5 members in Arabidopsis. To further dissect the role of WEI8 and WEI8-like (WEL) genes in auxin biosynthesis, to understand their regulation by ethylene, and to identify additional genetic elements in the auxin biosynthetic pathway, the following specific goals are set. 1) Determine the role of WEI8 and its closest homologues WEL1 and WEL2 in the ethylene response. 2) Determine the role of WEI8, WEL1, and WEL2 in auxin biosynthesis. 3) Identify and characterize new wei mutants. Broader Impact. Modification of plant responses to specific hormones can be utilized to improve agricultural production. These manipulations often result in collateral adverse effects due to the diversity of functions that a single hormone has during development. Understanding of how a hormone produces completely different effects dependent on the tissue, developmental and environmental conditions, etc. is, therefore, critical for the intelligent manipulation of plant production. This project will provide basic information on the genetics of auxin biosynthesis, thus enabling people to effectively control the myriad of processes regulated by auxin in plants. An important part of the funds will be dedicated to training students and postdoctoral fellows in basic, as well as applied plant biology. As part of this training, all involved personnel will be able to attend scientific meetings to become exposed to the latest advances in the field of their research and share their own findings.