Control of Shoot apex indeterminacy by TERMINAL FLOWER1

嫩芽结构——嫩芽的分枝模式和何时/何处开花——对于自然环境中的植物在生长季节产生足够的后代和作物的产量（生物量或果实/种子）非常重要。瓦格纳实验室正在研究一种调节所有开花植物茎结构的蛋白质。该项目的长期目标是根据不同的环境条件和不同的植物用途，精确地调节茎结构，一方面是多叶蔬菜和生物燃料，另一方面是水果和谷物。为了实现这一目标，该实验室正在将诱导遗传操作与高分辨率空间和时间测量相结合，这些测量将有助于微调这一过程。除了寻找加强粮食安全的可持续解决方案外，社会效益还包括在两个学期的基于课程的本科生研究经验（CURE）实验室课程中培训20名本科生进行对该提案很重要的研究。基于体内数据和模型，茎结构的一个关键决定因素是主茎和侧原基采用开花命运的时间。许多实验室的研究表明，TERMINAL FLOWER1基因及其同源物在阻止茎尖的确定性（花的命运）中起着关键作用。在tfl1突变体中，茎变成顶花，导致地上干细胞池分化。在这个建议中，我们解决了基本的发育生物学问题，即TFL1如何控制茎尖干细胞的维持（不确定性）或分化（确定性）。此外，TFL1积累或活性的降低彻底改变了包括番茄、大豆和棉花在内的几种作物，因为梢的确定性可以通过密集种植实现可持续的产量增加。然而，人们对TFL1的积累是如何控制的知之甚少。我们将确定促进茎尖TFL1上调的增强子和转录因子。也不知道TFL1是如何阻碍确定性的。我们将确定在茎中促进含有茎尖的干细胞池分化的关键直接TFL1抑制基因和途径。所获得的见解将促进对从干细胞维持到茎尖分化的转变的理解，以及茎结构是如何被控制的，并有助于实现未来农学上重要性状的定制工程。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Shoot architecture – the branching pattern of a shoot and when/where it forms flowers - is important for plants in natural environments to make sufficient offspring in the growing season and for yield (biomass or fruits/seeds) in crops. The Wagner lab is investigating a protein that regulates shoot architecture in all flowering plants. The long-term goal of this project is to precisely modulate shoot architecture for different environmental conditions and for different plant uses, leafy vegetables and biofuels on one hand or fruits and grains on the other. To achieve this goal, the lab is coupling inducible genetic manipulations with high resolution spatial and temporal measurements changes in the accumulation of unknown regulators of shoot architecture that will help fine-tune this process. Besides finding sustainable solutions for enhancing food security, societal benefits include training 20 undergraduate students in research important for this proposal in two semester-long Course-based Undergraduate Research Experiences (CURE) laboratory courses. Based on in vivo data and modeling, a key determinant of shoot architecture is the time at which the main shoot and the lateral primordia adopt floral fate. Work by many laboratories points to a pivotal role of the TERMINAL FLOWER1 gene and its orthologs in preventing determinacy (flower fate) of the shoot apex. In tfl1 mutants, the shoot becomes a terminal flower leading to differentiation of the above ground stem cell pool. In this proposal we address the fundamental developmental biology question how maintenance (indeterminacy) or differentiation (determinacy) of the stem cells in the shoot apex are controlled by TFL1. Moreover, reduced TFL1 accumulation or activity revolutionized several crops including tomato, soybean, and cotton because shoot determinacy enables sustainable yield increases by allowing dense planting. Yet how TFL1 accumulation is controlled is poorly understood. We will identify enhancers and transcription factors that promote TFL1 upregulation in the shoot apex. It is also not known how TFL1 blocks determinacy. We will define key direct TFL1- repressed genes and pathways in the shoot that promote differentiation of the stem cell pool containing shoot apex. Insight gained will advance understanding of the switch from stem cell maintenance to differentiation at the shoot apex, how shoot architecture is controlled, and help enable future tailored engineering of agronomically important traits.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.