Collaborative Research: Root-to-Shoot Communication via the bps Signal

干旱导致农业产量大幅下降。减轻与干旱有关的损失的一个重要步骤是充分了解人们对干旱的看法如何导致增长放缓及其对农业生产的相关影响。对干旱的最早感知发生在根遇到干燥的土壤时，由此产生的全植物反应被认为是由从根到地上移动的移动化学信号引起的。Sieburth实验室发现了一个高度保守的基因家族，该家族调节根到冠信号的产生，足以诱导干旱反应。这项研究的目的是鉴定这种信号分子。Sieburth和Dilkes实验室将使用基于代谢、遗传和基因表达的方法。这种策略的组合应该在化学上识别移动信号，并建立其与根到枝信号的其他已知成分的关系。了解根冠信号的化学特性可能会导致新的农业实践的发展，从而促进更大的粮食安全。植物对干旱的反应包括地上部合成脱落酸(ABA)和生长速度下降。因为大多数干旱反应是在地上部测量的，而植物的根被认为是最初检测干旱条件的，所以科学家们长期以来一直假设有一种移动的根到地上部的化学信号来协调干旱反应。拟南芥的BYPASS1(Bps1)突变体具有生长停滞的表型，这种表型是由bps1根中过量产生的嫁接可传递信号引起的。转录学和激素测定表明，这种可移动化合物足以诱导野生型新梢合成ABA，遗传分析表明生长停滞与ABA无关。该项目的目标是对这种过度生产的化合物进行化学鉴定。实验将使用先前建立的提取方法，用超高效液相色谱进行分级，并用质谱仪进行分析。其他实验将使用标记的前体和前体类似物；这些将澄清活性产品中所需的前体的结构成分，使用标记的前体的时间分辨分析应证明其生物合成途径是有用的。此外，还将比较bps1和野生型根转录本，并进行反向遗传分析，以测试差异表达基因是否是产生可移动化合物所必需的。最后，将在另一个植物物种中产生bps1突变体，并对其代谢组进行分析；本实验将检验这种干旱诱导的根冠化合物在不同植物物种中是相同的假设。不同的本科生和高中生将通过这笔赠款接受培训；对代表性不足群体的广泛宣传包括与当地社区大学的互动。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Drought causes dramatic reductions in agricultural yields. An important step toward mitigating drought-associated losses is to fully understand how perception of drought causes reduced growth, and its associated impacts on agricultural production. The earliest perception of drought occurs as roots encounter dry soil, and the resulting whole-plant responses are believed to arise from a mobile chemical signal that moves from roots to shoots. The Sieburth lab has discovered a highly conserved gene family that regulates production of a root-to-shoot signal that is sufficient to induce drought responses. The goal of this research is to identify this signaling molecule. The Sieburth and Dilkes labs will use metabolomic, genetic, and gene expression based approaches. This combination of strategies should chemically identify the mobile signal and establish its relationship to other known components of root-to-shoot signaling. Knowing the chemical identity of the root-to-shoot signal could lead to development of new agricultural practices that promote greater food security.Plants drought responses include synthesis of abscisic acid (ABA) in the shoots, and decreased growth rates. Because most drought responses are measured in shoots, whereas the plant root is believed to initially detect drought conditions, scientists have long postulated a mobile root-to-shoot chemical signal that coordinates drought responses. The bypass1 (bps1) mutant of Arabidopsis has a growth-arrest phenotype caused by a graft-transmissible signal over-produced in bps1 roots. Transcriptomics and hormone measurements demonstrated that this mobile compound is sufficient to induce ABA synthesis in wild-type shoots, and genetic analyses demonstrated that growth arrest is independent of ABA. This project's goal is chemical identification of this over-produced compound. Experiments will use previously established extraction methods, fractionation by Ultra Performance Liquid Chromatography, and analysis by mass spec. Other experiments will use a labeled precursor and precursor analogs; these will clarify the structural components of the precursor that are required in the active product, and time-resolved assays using the labeled precursor should prove informative for its biosynthetic pathway. In addition, bps1 and wild type root transcriptomes will be compared, and reverse genetic analyses will be carried out to test whether differentially expressed genes are necessary to produce the mobile compound. Finally, bps1 mutants will be generated in another plant species, and its metabolome analyzed; this experiment will test the hypothesis that this drought-induced root-to-shoot compound is the same in different plant species. Diverse undergraduates and high-school students will be trained through this grant; broad outreach to under-represented groups includes interaction with local community colleges.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.