Biophysics of Development of the Plant Shoot

植物多细胞发育涉及基因组与宏观表型之间的长因果链。细胞行为是一个关键的中间阶段。一方面，基因组提供了细胞行为的基础。另一方面，细胞行为通过时间和空间的整合，产生了连续的发育阶段。格林博士专门研究因果链的后几个方面。格林博士从生长细胞壁中纤维素的定向增强角度研究芽的发育。细胞在有丝分裂时维持或调整纤维素合成的方向。一种解释叶子的起源和间距的生物物理理论，叶分性，正在发展。它的主要宗旨是，最近形成的叶子的生长通过拉伸其细胞来影响顶圆顶，然后在圆顶上建立新的加固模式。这可以解释后续叶子的放置。现在，他提议通过改变器官拉伸模式和研究细胞反应，对细胞拉伸和强化行为之间明显的关键关系进行实验测试。他还提出要找出目前的理论是否可以扩展到其他的层序模式，以及它是否可以应用于叶子的形成。生物物理解释的充分性将通过一个有限元程序进行测试，该程序将模型分生组织中的物理力和细胞反应联系起来。应该得出一个关于芽发育的一般生物物理理论。这个项目的研究集中在植物继承其几何特征的方式上。最著名的植物嫩芽图案的例子是向日葵花头上的螺旋线和松果鳞片上的螺旋线。这些螺旋形图案也出现在温带大多数植物的叶片图案中。显然，植物有一个“发育引擎”，以特定的模式产生叶子。目前的研究是关于这些模式形成的细胞基础。这些模式是由茎尖的活动循环产生的。在茎尖，叶或其他附属物在细胞表面周围的增强图案的不连续点上产生。这些强化模式是纤维素微原纤维的结果。一旦叶片形成，其基部的生长作用于邻近的组织，拉伸它。这会引起邻近细胞的反应，从而产生新的不连续。因此，表面的不规则导致器官，器官产生不规则。这种循环可以继续下去，使一种固定的模式永久化。这项研究是为了扩展所有模式的解释，并检查物理拉伸和改变强化方向的细胞反应之间明显的关键联系。

Multicellular development in plants involves a long causal chain between genome and macroscopic phenotype. Cell behavior is a key intermediate stage. One the one hand the genome provides the basis for the cell behavior. On the other, the cell behavior, when integrated through time and space, produces the successive developmental stages. Dr. Green specialize in these later aspects of the causal chain. Dr. Green studies the development of the shoot in terms of the directional reinforcement, by cellulose, in the walls of growing cells. Cells maintain, or reorient, the direction of cellulose synthesis at mitosis. A biophysical theory to explain the origin and spacing of leaves, phyllotaxis, is being developed. Its main tenet is that growth of recently formed leaves influences the apical dome by stretching its cells which then establish new reinforcement patterns on the dome. This can explain the placement of subsequent leaves. Now he proposes to test experimentally the apparent key relationship- between cell stretch and reinforcement behavior by altering organ stretch patterns and studying cell responses. He also proposes to find out if the present theory can be extended to additional phyllotactic patterns and if it can be applied to the generation of form in leaves. Sufficiency of the biophysical explanations will be tested by a finite element program which correlates physical forces and cell responses in model meristems. A general biophysical theory for shoot development should result. %%% Research in this project centers on the way that plants inherit their geometrical features. The best known examples of pattern in plant shoots are the spiral lines seen in the heads of sunflowers and the helical lines made by the scales on a pine cone. These spiral patterns are also found in the leaf patterns of most plants growing in temperate zones. Obviously, plants have a "developmental engine" that produces leaves in a pattern specific to the plant. The present research is concerned with the cellular basis of the formation of these patterns. The patterns are generated by a cycle of activity at the stem tip. At the stem tip, leaves or other appendages, arise at points of discontinuity in the reinforcements patterns around cell surfaces. These reinforcement patterns are a result of cellulose microfibrils. Once a leaf is establishes, the growth of its base act of the adjacent tissue, stretching it. This causes a response in neighboring cells which create new discontinuities. Thus surface irregularities lead to organs and the organs make irregularities. The cycle can go on to perpetuate a fixed pattern. This research is to expand this interpretation of all patterns and to examine the apparently key connection between physical stretch and the cell response which alters reinforcement direction.