Kiss John Z, Correll Melanie J, Mullen Jack L, Hangarter Roger P, Edelmann Richard E
Department of Botany, Miami University, Oxford, OH, USA.
Gravit Space Biol Bull. 2003 Jun;16(2):55-60.
The interactions among tropisms can be critical in determining the final growth form of plants and plant organs. We have studied tropistic responses in roots as an example of these type of interactions. While gravitropism is the predominant tropistic response in roots, phototropism also plays a role in the oriented growth in this organ in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism. In the flowering plant Arabidopsis, the photosensitive pigments phytochrome A (phyA) and phytochrome B (phyB) mediate this positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. While blue-light-based negative phototropism is primarily mediated by the phototropin family of photoreceptors, the phyA and phyAB mutants (but not phyB) were inhibited in this response relative to the WT. The differences observed in phototropic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in plants and that phytochrome plays a key role in integrating multiple environmental stimuli.
向性之间的相互作用在决定植物和植物器官的最终生长形态方面可能至关重要。我们以根部的向性反应为例研究了这类相互作用。虽然重力向性是根部主要的向性反应，但在开花植物中，光向性也在该器官的定向生长中发挥作用。在蓝光或白光下，根表现出负向光性，但红光会诱导正向光性。在开花植物拟南芥中，光敏色素光敏色素A（phyA）和光敏色素B（phyB）介导了根部基于红光的正向光反应，因为单突变体（以及双phyAB突变体）在这种反应中严重受损。虽然基于蓝光的负向光性主要由光受体的向光素家族介导，但相对于野生型，phyA和phyAB突变体（但不是phyB突变体）在这种反应中受到抑制。在向光反应中观察到的差异并非由于生长限制，因为所有测试突变体的生长速率与野生型相比没有显著差异。因此，我们的研究表明，蓝光和红光系统在植物中相互作用，并且光敏色素在整合多种环境刺激方面起着关键作用。
