Collaborative Research: The Role of Tryptophan Metabolism in Auxin Homeostasis

植物和微生物在从色氨酸合成化合物的能力上是独一无二的。这些化合物之一是吲哚-3-乙酸，它是植物生长调节剂中的一个重要成员，称为生长素。吲哚-3-乙酸几乎由所有植物物种合成。在十字花科植物拟南芥中，色氨酸也用于产生植物防御化合物吲哚芥子油苷（IGs）和camalexin。在拟南芥中有证据表明，用于产生这些不同的拟南芥衍生化合物的生物合成途径之间存在复杂的串扰。非十字花科烟草中的次级代谢物谱不包括IG或camalexin。因此，烟草提供了一个易处理的替代模型系统，其中色氨酸代谢可以比较的拟南芥。本研究的目的是了解色氨酸代谢途径之间的相互作用是相同的或不同的拟南芥和其他植物物种，不产生相同的光谱的色氨酸衍生化合物作为拟南芥。该项目的研究范围是双重的：1）使用先前鉴定的色氨酸代谢受干扰的突变体植物来确定预测作为吲哚-3-乙酸生物合成中间步骤的化合物的作用。此外，将鉴定在这些代谢途径中被破坏的新突变体。2）确定哪些已知的吲哚-3-乙酸生物合成途径有助于形成化学上不同的天然生长素，称为吲哚-3-丁酸。这项研究的更广泛的影响包括生物化学和遗传学方法的研究生培训。这项培训将为他们在植物生物化学和代谢组学领域的更高级职位做好准备。此外，这项研究将作为三个机构（马萨诸塞州阿默斯特大学、波士顿大学和林肯大学）之间的合作进行，这三个机构是国家科学基金会支持的联盟的伙伴机构，旨在增加少数民族在科学技术、工程和数学（STEM）学科的教授人数。林肯大学的学生将在马萨诸塞州大学和波士顿大学的PI实验室参加正在进行的夏季少数民族研究项目，从而促进三个实验室之间的互动。林肯大学学生在三个PI之间的共同指导将有助于识别，招聘和指导对植物生物学研究生课程感兴趣的少数民族学生。

Plants and microbes are unique in their ability to synthesize compounds from the amino acid tryptophan. One of these compounds is indole-3-acetic acid, an important member of the class of plant growth regulators called auxins. Indole-3-acetic acid is synthesized by virtually all plant species. In the cruciferous plant, Arabidopsis thaliana, tryptophan is also used to produce the plant defense compounds indole glucosinolates (IGs) and camalexin. There is evidence in Arabidopsis for intricate cross-talk between the biosynthetic pathways used to produce these different tryptophan-derived compounds. The secondary metabolite profile in the non-crucifer tobacco does not include IGs or camalexin. Thus, tobacco provides a tractable alternative model system in which Trp metabolism can be compared to that of Arabidopsis.The goal of this research is to understand how the interactions among tryptophan metabolism pathways are the same or different between Arabidopsis and other plant species that do not produce the same spectrum of tryptophan-derived compounds as Arabidopsis. The research scope of this project is twofold:1) Use previously identified mutant plants perturbed in tryptophan metabolism to define the role of compounds predicted to serve as intermediate steps for the biosynthesis of indole-3-acetic acid. In addition, new mutants disrupted in these metabolic pathways will be identified.2) Determine which known indole-3-acetic acid biosynthetic pathways contribute to the formation of a chemically distinct naturally occurring auxin called indole-3-butyric acid. The broader impacts of this research include the training of graduate students in biochemical and genetic methodologies. This training will prepare them for more advanced positions in the fields of plant biochemistry and metabolomics. In addition, this research will be carried out as collaboration among three institutions (University of Massachusetts Amherst, Boston University and Lincoln University) that are partner institutions in an NSF-supported alliance designed to increase the number of minorities in the professoriate of science technology, engineering and mathematics (STEM) disciplines. Interactions between the three labs will be facilitated by having students from Lincoln University participate in ongoing summer minority research programs in the laboratories of the PIs from University of Massachusetts and Boston University. Co-mentorship of Lincoln University students among the three PIs will facilitate the identification, recruiting and mentoring of minority students with an interest in plant biology graduate programs.