Collaborative Research: Conservation and Diversification of Regulatory Pathways Controlling Stem Cell Proliferation

干细胞经历自我更新，以产生更多的干细胞，以及产生的子代，然后再产生多种特化的细胞类型。在植物中，顶端分生组织(SAM)的细胞充当干细胞，产生更多的干细胞以及对叶、枝和果实有贡献的特殊细胞类型。这项研究调查了柑橘刺发育的基础，以此作为一种手段来理解干细胞增殖的终止是如何被控制的。刺来自不能自我更新的SAM细胞，而不是终末分化，这提供了一个独特的机会来探索SAM细胞的增殖是如何控制的。柑橘是探索这个问题的一个很好的研究系统，因为许多柑橘物种都有刺，而且有多种遗传和基因组工具可以用来处理柑橘。在这项研究中，来自柑橘的与干细胞增殖调控有关的候选基因将通过表达分析和新开发的转基因方法来研究它们在刺突发育中的作用。在一系列互补的实验中，将通过对有刺和无刺柑橘物种的转录进行全基因组比较来确定参与阻止干细胞增殖的关键基因。这些分析将开始定义对干细胞停滞非常重要的过程。他们还将阐明干细胞维持和分化的保守和新机制。柑橘的植株生长、果实产量和收获成本都受到多刺的影响，因此了解如何操纵刺产量将极大地影响这种宝贵的果树的经济效益。作为该项目的一部分，一名博士后助理、一名研究生和三名本科生将接受培训。此外，将在康涅狄格州纽哈文的沼泽植物园展出柑橘生物学，旨在提高公众对科学的认识和理解。

Stem cells undergo self-renewal to produce more stem cells, as well as to produce daughters that go on to produce multiple specialized cell types. In plants, cells of the shoot apical meristem (SAM) act as stem cells, giving rise to more stem cells as well as specialized cell types contributing to the leaves, branches and fruit. This study investigates the basis for thorn development in Citrus as a means to understand how the termination of stem cell proliferation is controlled. Thorns arise from SAM cells that fail to self-renew, and instead terminally differentiate, providing a unique opportunity to explore how SAM cell proliferation is controlled. Citrus is an excellent study system to explore this question as many Citrus species possess thorns, and multiple genetic and genomic tools exist for work with Citrus. In this study, candidate genes from Citrus that have been implicated in regulating stem cell proliferation will be examined for their roles in thorn development using expression analyses and employing newly developed transgenic approaches. In a complementary set of experiments, key genes involved in the arrest of stem cell proliferation will be identified via genome-wide comparisons of the transcriptomes of thorned vs. thornless Citrus species. These analyses will begin to define the processes important for stem cell arrest. They will also elucidate conserved and novel mechanisms of stem cell maintenance and differentiation. Citrus plant growth, fruit yield and harvest costs are all affected by thorniness, so understanding how to manipulate thorn production will greatly impact the economics of this valuable fruit crop. A postdoctoral associate, a graduate student and three undergraduates will receive training as a part of this project. In addition, a display of Citrus biology will be mounted at the Marsh Botanical Gardens, NewHaven, CT, aimed at promoting public awareness and understanding of science.