A Novel Mechanism Regulating Inflorescence Development in Tomato

在自然界和农业中，植物的生产力都依赖于花卉，花卉是果实和种子的基础。根据不同的植物，在繁殖枝上形成的花的数量（称为花序）可能有很大的不同。发现负责这种物种特异性多样性的基因，并了解这些基因如何共同控制花卉生产，是植物生物学的主要焦点，与作物改良直接相关。在番茄及其茄科的近亲中，如茄子、辣椒和土豆，每个花序上的花的产量差别很大，从单一枝上的一朵花，如胡椒，到许多枝上的几十朵花，如几种野生番茄。该项目将利用在番茄中发现的开花变化来研究一组基因，这些基因是产生多花花序所需的，因此是所有番茄品种所熟悉的“藤上番茄”结构特征。通过使用新的基因编辑技术使这些基因突变，将有可能解剖这些基因编码的蛋白质如何精确地控制每棵番茄植株的时间、地点以及产生多少花朵和果实。该项目的结果将揭示新的开花基因及其作用模式，然后可以利用经典和现代遗传工具对其进行靶向修饰，以提高番茄和许多相关作物的产量。此外，在市中心的一所中学，一项拓展计划将教育年轻学生了解基因工程的过程，以帮助消除对转基因食品的普遍误解。所有地上植物的生长都源于茎的分生组织，小群体的干细胞产生了巨大的结构多样性，特别是在花序中。这种多样性的核心是分生组织成熟的关键过程，但人们对这个过程知之甚少。植物发育的一个主要问题是如何控制分生组织成熟的时间，从而控制花序和花的产生。与其他模式植物的分生组织成熟相比，番茄及其相关的茄科植物的分生组织成熟知识要少得多，尽管它们代表了广泛的合胞生长习惯。最近对番茄的研究揭示了一种新的成熟程序，由TMF基因编码的一种新的转录调节因子定义。本项目将遗传学、基因组学和生物化学相结合，研究TMF及其相互作用的蛋白伙伴调控分生组织成熟的机制。在Aim 1中，TMF转录辅助因子将从遗传、分子和发育方面进行研究。在Aim 2中，我们将结合RNA-seq和ChIP-seq来探索TMF的转录靶点及其表达网络。在Aim 3中，TMF家族成员将使用CRISPR/Cas9进行表征。该项目包括第一个分子机制研究，以了解分生组织成熟如何被微调以定量控制合生植物的花朵生产。这一发现将揭示分生组织成熟的新原理，从而能够调节花序结构和花卉生产，从而造福农业。

In both nature and agriculture plant productivity depends on flowers, which are the foundation for fruits and seeds. Depending on the plant, the number of flowers that form on reproductive branches, known as inflorescences, can vary substantially. Discovering the genes responsible for this species-specific diversity, and understanding how these genes work together to control flower production, is a major focus in plant biology with direct relevance for crop improvement. In tomato and its close relatives in the nightshade (Solanaceae) family, such as eggplant, pepper, and potato, flower production on each inflorescence varies dramatically, from a solitary flower on a single branch, as in pepper, to dozens of flowers on many branches, as in several wild tomatoes. This project will take advantage of variation in flower production found in tomato to study a group of genes that are required for generating multi-flowered inflorescences, and thus the familiar "tomatoes-on-the-vine" architecture characteristic of all tomato varieties. By mutating these genes using new gene-editing technology, it will be possible to dissect how the proteins encoded by these genes control precisely when, where, and how many flowers and fruits are produced on each tomato plant. Results from this project should reveal new flower-production genes and their modes of action, which can then be targeted for modification using both classical and modern genetic tools to improve yields in tomato and many related crops. Additionally, an outreach program at an inner-city middle school will educate young students on the process of genetic engineering to help shed popular misconceptions about genetically modified food.All above ground plant growth originates from shoot meristems, small populations of stem cells that give rise to vast architectural diversity, particularly in inflorescences. At the heart of this diversity lies a critical, yet poorly understood, process of meristem maturation. A major question in plant development is how timing of meristem maturation, and thus inflorescence and flower production, is controlled in different plants. Compared to knowledge on meristem maturation in other model plants, much less is known in tomato and related Solanaceae, despite representing the widespread sympodial growth habit. Recent work in tomato has exposed a new maturation program, defined by a novel transcriptional regulator encoded by the TMF gene. This project integrates genetics, genomics and biochemistry to study the mechanisms by which TMF and its interacting protein partners regulate meristem maturation. In Aim 1, TMF transcriptional co-factors will be studied genetically, molecularly, and developmentally. In Aim 2, transcriptional targets of TMF and its expression network will be explored by integrating RNA-seq and ChIP-seq. In Aim 3, TMF family members will be characterized using CRISPR/Cas9. This project comprises a first molecular mechanistic study to understand how meristem maturation is fine-tuned to quantitatively control flower production in sympodial plants. The findings should reveal new principles of meristem maturation that can enable modulation of inflorescence architecture and flower production to benefit agriculture.