Characterization of PiCDPK1 Mediated Signaling Pathways Regulating Pollen Tube Tip Growth

生产种子或果实是大多数农业和园艺实践的目标。在大多数情况下，种子和果实的发育需要由花粉传递的精子使胚珠受精。在大多数开花植物中，胚珠被包裹在母体组织中。为了穿过这个屏障，花粉产生导管，通过一个被称为尖端生长的过程穿透雌性组织。这个过程是如何调控的尚不清楚，但它是植物有性生殖的关键，也是受精和种子形成的遗传操纵的潜在目标。钙离子在花粉管顶端生长中起着重要的调节作用，并且已经确定了一种控制花粉管生长极性的钙调节酶（PiCDPK1）。这种酶是一种蛋白激酶，通过在其蛋白骨架上添加磷酸基团来调节下游信号成分。该项目的目标是利用分子遗传学和生物化学方法表征两个这样的下游成分。初步结果表明，这些成分的磷酸化形式可以介导花粉管生长的抑制或促进。我们将利用转基因方法详细研究这种可能性。该研究将显著提高对花粉管生长信号事件的认识，并有望为控制这一过程提供分子工具。此外，由于钙参与植物生长发育的许多方面，该结果可能对植物细胞信号传导具有更广泛的意义。拟议的研究将为一名博士后、一名研究生和几名本科生提供各种细胞和分子生物学技术的培训。通过暑期实习，每年将有两名高中生获得最先进的分子生物学技术的宝贵经验。

Production of seeds or fruits is the goal of most agricultural and horticultural practices. In most cases seed and fruit development requires fertilization of ovules by sperm delivered by pollen. In most flowering plants ovules are enclosed within maternal tissues. To traverse this barrier, pollen produce tubes that penetrate the female tissues by a process known as tip-growth. How this process is regulated is not well understood but is key to plant sexual reproduction and is a potential target for the genetic manipulation of fertilization and seed set.Calcium ions play an important regulatory role in tip-growth and a calcium-regulated enzyme (PiCDPK1), which controls pollen tube growth polarity, has been identified. This enzyme is a protein kinase which regulates downstream signaling components by adding phosphate groups to their protein backbones. The objectives of this project are to characterize two such downstream components using molecular genetic and biochemical approaches. Preliminary results suggest that the phosphorylated forms of these components can mediate the inhibition or enhancement of pollen tube growth. This possibility will be investigated in detail using transgenic approaches.This study will significantly enhance knowledge of signaling events in pollen tube growth and is expected to provide molecular tools with which this process can be manipulated. Furthermore, the results may have broader implications for plant cell signaling as calcium is involved in many aspects of plant growth and development.The proposed research will provide training for a post-doctoral, a graduate and several undergraduate students in a variety of cell and molecular biology techniques. Through summer internships, two high school students per year will gain valuable experience in state of the art molecular biology techniques.