The Regulation of Leaf Cell Expansion by Light and Ion Flux

光与生长中的叶细胞质膜之间的相互作用是这一提议的重点。叶子的展开需要光线。大多数双子叶植物的叶片在黑暗中仍然很小，对低通量率的(红色)光有轻微的扩展，但它们需要持续暴露在高通量率的(白)光中才能达到完整的大小。这种光反应是发生在绿色组织中的光敏色素的“高辐射”反应，它可能涉及蓝光感受器的额外活动。对红光和蓝光通过两个光感受器刺激叶片细胞生长，2)蓝光通过质膜电子传递系统驱动质子外流，3)红光通过光敏色素调节离子通道钾离子通量的假设，探讨了红光吸收对细胞生长的转导机制。这些可能性将在普通菜豆的初生叶中进行测试，这为光刺激细胞扩张提供了一个有据可查的模型系统。他们的反应的普遍性将在其他物种(杨树、豌豆、凤仙花)的叶片上进行测试，这些树种对光的反应不同。这项研究的目标是确定植物中叶细胞的扩大是如何控制的，以及参与植物生长对光反应的分子的性质。

The interaction between light and the plasma membrane of growing leaf cells is the focus of this proposal. Leaf expansion requires light. Most dicotyledonous leaves remain very small in the dark, expand slightly in response to (red) light of low fluence rates, but they require continuous exposure to (white) light of high fluence rates to reach full size. this photoresponse is a "high- irradiance" response of phytochrome occurring in green tissue, and it may involve additional activity of a blue-light receptor. The mechanism(s) transducing light absorption to cell growth will be pursued by testing the following hypotheses: 1) red and blue light act through two photoreceptors to stimulate cell growth in leaves, 2) blue light stimulates proton efflux driven by an electron transport system in the plasma membrane, 3) red light acts through phytochrome to modulate potassium flux through ion channels. These possibilities will be tested in primary leaves of Phaseolus vulgaris L. which provide a well documented model system for light stimulated cell expansion. The generality of their responses will be tested in leaves of other species (Populus, Vicia, Impatiens) which grow differently in response to light. %%% The goal of the research is to determine how leaf cell enlargement in plants is controlled and what is the nature of the molecules involved in their growth response to light.