IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y Técnicas, 1417 Buenos Aires, Argentina.
Plant J. 2011 Dec;68(5):919-28. doi: 10.1111/j.1365-313X.2011.04745.x. Epub 2011 Oct 4.
The light environment provides signals that play a critical role in the control of stem growth in plants. The reduced irradiance and altered spectral composition of shade light promote stem growth compared with unfiltered sunlight. However, whereas most studies have used seedlings exposed to contrasting but constant light treatments, the natural light environment may exhibit strong fluctuations. As a result of gaps in the canopy, plants shaded by neighbours may experience sunflecks, i.e., brief periods of exposure to unfiltered sunlight. Here, we show that sunflecks are perceived by phytochromes A and B, and inhibit hypocotyl growth in Arabidopsis thaliana mainly if they occur during the final portion of the photoperiod. By using forward and reverse genetic approaches we found that ELONGATED HYPOCOTYL 5, LATE ELONGATED HYPOCOTYL, PHYTOCHROME KINASE SUBSTRATE 4 and auxin signalling are key players in this response.
光环境提供的信号在植物干细胞生长的控制中起着关键作用。与未过滤的阳光相比，遮光环境中的低光照度和改变的光谱组成促进了茎的生长。然而，尽管大多数研究都使用了暴露在对比但恒定光照处理下的幼苗，但自然光照环境可能会出现强烈的波动。由于树冠的缝隙，被邻居遮挡的植物可能会经历阳光斑点，即短暂暴露在未过滤的阳光下的时期。在这里，我们表明，phytochromes A 和 B 可以感知阳光斑点，并在光周期的最后部分发生时主要抑制拟南芥的下胚轴生长。通过使用正向和反向遗传方法，我们发现 ELONGATED HYPOCOTYL 5、LATE ELONGATED HYPOCOTYL、PHYTOCHROME KINASE SUBSTRATE 4 和生长素信号是该反应的关键参与者。
