Regulation of in vitro morphogenesis

细胞在向器官或生物体生长时如何获得特定特征是动物和植物发育生物学中一个基本但知之甚少的问题。* 植物形态发生依赖于细胞改变其命运的能力，这一过程在茎和根顶端分生组织（SAM和RAM）中得到了最好的例证。 分生组织作为多能细胞的储存库，产生用于侧器官形成的衍生物。 因此，多能细胞的自我更新和保留以及其衍生物的分化之间的平衡是分生组织功能的关键。植物球蛋白（Pgbs），具有一氧化氮（NO）清除特性的植物血红蛋白，通过在胁迫条件下延迟分化和维持分生组织细胞处于未分化状态来影响细胞命运承诺 * 和重新编程细胞命运。这项研究计划包括两个主要目标。 第一个目标将检查的个体发育的RAM和SAM从培养的拟南芥根和Pgbs的参与（通过实验改变其在培养细胞中的量）在分析的多能分生细胞的规格。Pgb反应的中间体，如一氧化氮，乙烯和细胞氧化还原状态的变化也将被调查有关SAM和RAM的形成。 解剖根分生组织的隔间，包括负责赋予多能性的静止细胞，也将被用来增加这些研究的分辨率。 总的来说，来自该目标的结果将提供在获得多能性期间整合Pgb作用和响应的模型。第二个目标是通过从拟南芥体细胞组织诱导胚性细胞来确定体细胞-胚性命运转变的机制。 在该体外系统中，胚胎发生细胞由WUSCHEL（WUS）的表达限定，并且Pgb的抑制增加了表达WUS的胚胎发生细胞的数量。 拟议的研究将集中在Pgb如何调节WUS和规格的胚胎发生细胞的调查细胞分裂素和生长素介导的途径在体内分生组织细胞规格。显微切割和从相邻的体细胞中分离新生的胚胎发生细胞将确定决定体细胞-胚胎发生转变的因素。该计划的新颖之处在于利用和整合了大量的技术（结构，生理和分子）来测试所提出的控制细胞命运重定向的发育模型，以应对不断变化的培养条件。 结果将是开创性的，因为它们不仅将推进胚胎发生领域，而且还将推进所有那些需要重新定向细胞行为的过程，这些过程对植物繁殖，生产力和在不利条件下的生存至关重要。

How cells acquire specific characteristics as they grow towards an organ or organism is a fundamental and yet poorly understood question in animal and plant developmental biology. *********Plant morphogenesis relies on the ability of cells to redirect their fate, a process best exemplified in the shoot and root apical meristems (SAMs and RAMs). Meristems serve as a reservoir of pluripotent cells producing derivatives recruited for the formation of lateral organs. Balance between self-renewal and retention of pluripotent cells, and differentiation of their derivatives, is therefore key for meristem function. Phytoglobins (Pgbs), plant hemoglobins with nitric oxide (NO) scavenging properties, influence cell fate commitment***and reprogram cell fate by delaying differentiation and maintaining meristematic cells in an undifferentiated state during conditions of stress.******This program of research comprises two main objectives. The first objective will examine the ontogeny of RAMs and SAMs from cultured Arabidopsis roots and the participation of Pgbs (by experimentally altering their amount in cultured cells) in the specification of the pluripotent meristematic cells analysed. Intermediates of Pgb-responses, such as nitric oxide, ethylene and changes in cellular redox state will also be investigated in relation to SAM and RAM formation. Dissection of root meristem compartments, including the quiescent cells responsible for conferring pluripotency, will also be employed to increase the resolution of these studies. Collectively, results from this objective will provide a model integrating Pgb action and response during the acquisition of pluripotency.*******The second objective will define the mechanisms underlying the somatic-embryogenic fate transition by inducing embryogenic cells from Arabidopsis somatic tissue. In this in vitro system, embryogenic cells are defined by the expression of WUSCHEL (WUS), and suppression of Pgb increases the number of WUS-expressing embryogenic cells. The proposed research will focus on how Pgb regulates WUS and the specification of embryogenic cells by investigating cytokinin- and auxin-mediated pathways operating during meristematic cell specification in vivo. The microdissection and separation of nascent embryogenic cells from the adjacent somatic cells will identify factors determining the somatic-embryogenic transition.**********The novelty of this program resides in the utilization and integration of a large number of techniques (structural, physiological and molecular) to test proposed developmental models controlling the redirection of cell fate in response to changing culture conditions. Results will be ground breaking in that they will advance not only the field of embryogenesis, but also all those processes requiring a redirection of cell behavior which are crucial for plant propagation, productivity, and survival under adverse conditions.******