Collaborative Research: Hormonal control of stamen filament growth

在植物和动物中，许多器官在发育过程中都会经历突增。许多花的器官在花开放的短时间内生长得非常快。为了成功繁殖，这种生长必须协调，以便将雄性和雌性器官适当地放置在授粉的位置，并且需要在最佳时间释放花粉。这个项目是为了研究植物激素如何刺激雄蕊的快速生长，雄蕊是产生花粉的雄花器官。在许多自花授粉的植物中，雄蕊花丝在花开放时拉长，将携带花粉的花药放置在雌性柱头附近。因此，花丝生长的时间和程度决定了受精和种子生产的效率，对作物育种和产量很重要。该项目将研究模式植物雄蕊花丝伸长过程中的细胞和分子事件，以详细揭示雄蕊如何快速生长而不弯曲，激素如何控制这种生长，以及花丝生长如何与花粉释放协调。在这项工作中产生的遗传工具可能使有针对性地修改花器官的生长，例如调节作物植物中花粉释放的位置和时间。发现的机制也将与调节其他器官（如叶子或果实）的生长有关。本科学生将通过在课程和研究实验室中开展研究项目来了解科学探究的方法。通过博物馆和校园活动进行的公众宣传将包括有关植物繁殖的信息。该项目旨在研究激素反应途径如何控制模式植物拟南芥雄蕊花丝快速而短暂的生长。两个生长素应答转录因子ARF6和ARF8介导对生长素激素的生长应答，并在花开放前刺激雄蕊花丝伸长。ARF6和ARF8还刺激另一种激素茉莉酸的产生，从而进一步加快花丝的生长速度，并促进花药开裂（花粉释放）所需的分化。延时共聚焦显微镜、单核RNA-Seq和荧光报告基因将用于重建快速生长的雄蕊花丝的三维细胞解剖、生长和分化。比较野生型和突变型与减少或增加激素反应和长丝生长将提供洞察如何激素的作用。生物物理、激素和基因操作，连同茉莉酸途径报告基因，将探索花丝生长与花药开裂所需的茉莉酸生产同时爆发的耦合机制。酵母和植物原生质体基因表达系统将用于鉴定能够独立于生长素调节激活转录的ARF6和ARF8突变体形式。这种生长素不依赖的突变将被设计到拟南芥植物中，以揭示生长素在花成熟和其他过程中的作用。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。

In both plants and animals, many organs undergo spurts of rapid growth as they develop. Many flower organs grow very quickly for a brief period as flowers open. For successful reproduction, such growth must be coordinated so as to place male and female organs appropriately for pollination, and pollen release needs to occur at an optimal time. This project is to study how plant hormones stimulate rapid growth in stamens, the male flower organs that produce pollen. In many self-pollinating plants, stamen filaments elongate as flowers open to place pollen-bearing anthers near the female stigma. The timing and extent of filament growth thus determines the efficiency of fertilization and seed production, and is important for crop breeding and yield. The project will examine cellular and molecular events during stamen filament elongation in a model plant, to reveal in detail how stamens grow quickly without buckling, how hormones control this growth, and how filament growth is coordinated with pollen release. Genetic tools generated in the work may enable targeted modification of growth in flower organs, for example to modulate the location and timing of pollen release in crop plants. The mechanisms discovered will also be relevant to modulating growth in other organs such as leaves or fruits. Undergraduate students will be introduced to methods of scientific inquiry through carrying out research projects both in courses and in the research labs. Public outreach through museums and campus events will include information on plant reproduction. The project is to study how hormone response pathways control very fast but transient stamen filament growth in the model plant Arabidopsis thaliana. Two auxin response transcription factors, ARF6 and ARF8, mediate growth responses to the hormone auxin, and stimulate stamen filament elongation just before flowers open. ARF6 and ARF8 also stimulate production of another hormone, jasmonate, which further amplifies filament growth rate, and also promotes differentiation needed for anther dehiscence (pollen release). Time-lapse confocal microscopy, single-nucleus RNA-Seq, and fluorescent reporter genes for selected vascular cell types will be used to reconstruct three-dimensional cellular anatomy, growth, and differentiation in rapidly growing stamen filaments. Comparisons of wild type and mutants with decreased or increased hormone responses and filament growth will provide insight into how the hormones act. Biophysical, hormonal, and genetic manipulations, together with jasmonate pathway reporter genes, will probe mechanisms that couple filament growth with the contemporaneous burst of jasmonate production needed for anther dehiscence. Yeast and plant protoplast gene expression systems will be used to identify mutant forms of ARF6 and ARF8 that can activate transcription independently of auxin regulation. Such auxin-independent mutations will then be engineered into Arabidopsis plants to reveal the role of auxin response in flower maturation and other processes.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.