RUI: Cellular Mechanisms of Paraheliotropism

9507385 Berg避光(向日性)是一种重要的逆境反应，使一些植物在炎热、干燥、明亮的条件下减少失水，降低叶温，减少对叶片的光伤害。减少光截获的能力是赋予一些豆类抗旱性的特性之一。虽然已知的刺激类向日性的因素被很好地描述(高温、干旱、高光强)，但几乎对叶片运动的细胞机制知之甚少。这种运动涉及叶片底部运动器官细胞的膨胀和收缩，需要考虑离子通道、渗透特性、细胞大小变化和物理作用力。这项拟议的项目有三个主要目标：1)比较已知的导致类向日性的刺激对切除的组织、分离的细胞和来自运动器官的原生质体的不同作用；2)确定运动细胞改变大小时细胞骨架的命运；以及3)确定哪些离子通道参与了与类日向性相关的细胞大小的变化。这个项目将通过建立两组可逆扩展的植物细胞之间的功能关系来推进科学知识，其中一组得到了很好的研究，另一组目前几乎没有得到研究。它将确定准向日性背后的机制，这是一种对本土物种和农学上重要的植物的生存和投射很重要的胁迫反应。

9507385 Berg Light-avoiding leaf movement (paraheliotropism) is an important stress response that allows some plants to reduce water loss, lower leaf temperature and decreases photodamage to leaves under hot, dry, bright condition. The capacity to reduce light interception is one of the properties that confers drought resistance on some legumes. While the factors known to stimulate paraheliotropism are well described (high temperature, drought, high light intensity), almost nothing is known about the cellular mechanisms underlying the movement of leaves. The movement involves the swelling and shrinking of cells of the motor organ at the base of leaves, requiring a consideration of ion channels, osmotic properties, cell size change, and physical forces. The proposed project has three principal objectives: 1) to compare how the stimuli known to cause paraheliotropism act differently upon excised tissue, isolated cells and protoplaqts from the motor organ; 2) to determine the fate of the cytoskeleton when motor cells change size; and 3) to determine which ion channels are are involved in cell size change associated with paraheliotropism. This project will advance scientific knowledge by establishing the functional relationships between the two major groups of reversibly expandable plant cells, one well studied, the other barely examined at this time. It will determine the mechanisms that underlie paraheliotropism, a stress response important for the survival and projectivity of native species and agronomically important plants.