Roles of homeodomain proteins in plant morphogenesis responding enviromental stimuli

植物的形态发生不仅受内在发育程序的调控，还受环境刺激的影响。尽管植物激素应该在这一复杂的过程中发挥关键作用，但它们在这一过程中的上下游成分仍不清楚。为了了解从环境刺激到植物形态发生的信号转导途径，我们正在研究HID-Zip型转录因子在这些途径中的作用。ATHB-1和ATHB-2是最先在拟南芥中发现的同源异型盒基因。利用表达ATHB-1、ATHB-2或其衍生物的转基因植株，分析了它们在植物形态发生和转录网络中的作用。结果发现，转ATHB-1基因的拟南芥植株叶片形态发生了变化。我们还发现ATHB-2参与了下胚轴和叶片细胞伸长方向的调节，并且ATHB-2似乎与远红光诱导的形态变化密切相关，即所谓的遮荫回避。

Plant morphogenesis is not only regulated by the intrinsic developmental program but also influenced by environmental stimuli. Although plant hormones should play a key role in this complex process, both their upstream and downstream elements in the process are still unclear. To understand signal transduction pathways from environmental stimuli to plant morphogenesis, we are studying roles of HID-Zip-type transcription factors in the pathways.ATHB-1 and ATHB-2 are homeobox genes that were first identified in Arabidopsis. Using transgenic plants expressing ATHB-1, ATHB-2, or their derivatives, we analyzed their roles in plant morphogenesis and transcriptional networks which they involved in. As results, we found that transgenic Arabidopsis plants carrying a modified ATHB-1 gene showed a morphological change in leaves. We also found that ATHB-2 is involved in the regulation of direction of cell elongation in a hypocotyle and leaves, and that ATHB-2 seems to be closely related with morphological changes induced by far-red-rich light, so-called "shade avoidance".