Regulation of in vitro morphogenesis

在动植物发育生物学中，细胞如何在向一个器官或有机体生长的过程中获得特定的特征是一个基本但却知之甚少的问题。*********植物的形态发生依赖于细胞改变其命运的能力，这一过程在茎和根尖分生组织（sam和RAMs）中得到了最好的例证。分生组织是多能细胞的储存库，产生的衍生物为侧壁器官的形成募集。因此，多能细胞的自我更新和保留及其衍生物的分化之间的平衡是分生组织功能的关键。植物红蛋白（Phytoglobins, Pgbs）是一种具有清除一氧化氮（NO）特性的植物血红蛋白，在逆境条件下通过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的承诺和重编程细胞命运。******这项研究计划包括两个主要目标。第一个目标是研究从培养的拟南芥根中提取的RAMs和sam的个体发生，以及Pgbs（通过实验改变其在培养细胞中的数量）在分析的多能分生细胞的规范中的作用。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研究与SAM和RAM形成的关系。解剖根分生组织室，包括负责赋予多能性的静止细胞，也将用于增加这些研究的分辨率。总的来说，这一目标的结果将提供一个在多能性获得过程中整合Pgb作用和反应的模型。*******第二个目标是通过从拟南芥体细胞组织中诱导胚性细胞来确定体细胞-胚性命运转变的机制。在这个体外系统中，胚性细胞是通过表达WUSCHEL （WUS）来定义的，抑制Pgb增加了表达WUS的胚性细胞的数量。本研究将通过研究细胞分裂素和生长素在体内分生组织细胞分化过程中介导的途径，重点研究Pgb如何调节WUS和胚胎性细胞的分化。显微解剖和分离新生胚胎细胞与相邻体细胞将确定决定体细胞-胚胎转变的因素。**********这个项目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）来测试所提出的发育模型，这些模型控制细胞命运的重定向，以响应不断变化的培养条件。结果将是突破性的，因为它们不仅将推进胚胎发生领域，而且还将推进所有需要重定向细胞行为的过程，这些过程对植物的繁殖，生产力和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.******