A Novel Mechanism Regulating Inflorescence Development in Tomato

在自然界和农业中，植物的生产力取决于花朵，花朵是果实和种子的基础。根据植物的不同，在生殖枝上形成的花的数量，称为花序，可以有很大的不同。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作用以控制花卉生产，是植物生物学的一个主要焦点，与作物改良直接相关。在番茄和茄科（茄科）的近亲中，如茄子、辣椒和马铃薯，每个花序上的花产量变化很大，从单个分支上的单瓣花（如辣椒）到许多分支上的数十朵花（如几种野生番茄）。该项目将利用在番茄中发现的开花变异来研究产生多花花序所需的一组基因，从而研究所有番茄品种的常见“藤上番茄”结构特征。通过使用新的基因编辑技术突变这些基因，将有可能剖析这些基因编码的蛋白质如何精确控制每株番茄植物何时、何地以及产生多少花和果实。该项目的结果将揭示新的开花基因及其作用模式，然后可以使用经典和现代遗传工具进行靶向修饰，以提高番茄和许多相关作物的产量。此外，一个在市中心中学的推广项目将教育年轻学生了解基因工程的过程，以帮助他们摆脱对转基因食品的普遍误解。所有地上植物的生长都起源于茎分生组织，这是一小部分干细胞，它们产生了巨大的结构多样性，特别是在花序中。在这种多样性的核心在于一个关键的，但知之甚少，分生组织成熟的过程。植物发育中的一个主要问题是不同植物的分生组织成熟的时间，以及花序和花的产生是如何控制的。与其他模式植物中的分生组织成熟知识相比，尽管番茄和相关茄科代表了广泛的合轴生长习性，但对番茄和相关茄科中的分生组织成熟知之甚少。最近在番茄中的研究揭示了一种新的成熟程序，该程序由一种新的转录调节因子所定义，该转录调节因子是由番茄红素基因编码的。本计画整合遗传学、基因组学与生物化学，研究拟南芥及其相互作用蛋白质伴侣调控分生组织成熟的机制。在目标1中，将从遗传学、分子学和发育学的角度研究转录辅助因子。在目标2中，将通过整合RNA-seq和ChIP-seq来探索BMPs的转录靶点及其表达网络。在目标3中，将使用CRISPR/Cas9来表征cDNA 3家族成员。该项目包括第一个分子机制研究，以了解分生组织成熟是如何微调，以定量控制花生产合轴植物。这些发现将揭示分生组织成熟的新原理，从而使花序结构和花卉生产的调制有利于农业。

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.