Instituto de Investigaciones Biológicas, CONICET-Universidad Nacional de Mar del Plata, Facultad de Ciencias Exactas y Naturales, Argentina.
IFEVA, Universidad de Buenos Aires and CONICET, Facultad de Agronomía, Argentina.
J Exp Bot. 2018 Jan 4;69(2):213-228. doi: 10.1093/jxb/erx295.
Auxin has emerged as a key player in the adjustment of plant morphology to the challenge imposed by variable environmental conditions. Shade-avoidance responses, including the promotion of stem and petiole growth, leaf hyponasty, and the inhibition of branching, involve an intimate connection between light and auxin signalling. Low activity of photo-sensory receptors caused by the presence of neighbouring vegetation enhances the activity of PHYTOCHROME INTERACTING FACTORs (PIFs), which directly promote the expression of genes involved in auxin biosynthesis, conjugation, transport, perception, and signalling. In seedlings, neighbour signals increase auxin levels in the foliage, which then moves to the stem, where it reaches epidermal tissues to promote growth. However, this model only partially accounts for shade-avoidance responses (which may also occur in the absence of increased auxin levels), and understanding the whole picture will require further insight into the functional significance of the multiple links between shade and auxin networks.
生长素已成为植物形态适应可变环境条件挑战的关键调节因子。避荫反应，包括促进茎和叶柄生长、叶片下弯和分枝抑制，涉及光和生长素信号之间的密切联系。由于邻近植被的存在导致光感觉受体活性降低，增强了 PHYTOCHROME INTERACTING FACTORS（PIFs）的活性，PIFs 直接促进参与生长素生物合成、共轭、运输、感知和信号转导的基因的表达。在幼苗中，邻体信号增加叶片中的生长素水平，然后生长素转移到茎中，到达表皮组织以促进生长。然而，该模型仅部分解释了避荫反应（即使在生长素水平没有增加的情况下也可能发生），并且要全面了解该现象，需要进一步深入了解荫蔽和生长素网络之间的多重联系的功能意义。
