阿拉伯芥中FIN219與FHY1交互作用調控光與茉莉酸訊息傳遞的研究

Abstract

植物可以偵測周圍環境訊息，以改變植物的生理反應、生長發育。而且光和多種植物賀爾蒙共同參與調控這些植物的反應之中，譬如調控植物的光型態發生。在幼苗階段時，FAR-RED INSENSITIVE 219 (FIN219) 參與在受phytochrome A (phyA)所調控的遠紅光[far-red (FR) light]訊息傳遞之中，且是茉莉酸訊息傳遞中非常重要的因子。Far-Red Elongated Hypocotyl 1 (FHY1) 是遠紅光訊息傳遞的正調控者，且在調控phyA進出細胞核的機制中扮演重要的角色。之前研究發現FIN219與FHY1在遠紅光下會交互作用。然而，相關分子機制以及它與茉莉酸訊息傳遞間的關係仍不太清楚。本研究發現FHY1的存在會促使受phyA磷酸化的FIN219穩定在細胞質中累積，且FIN219磷酸化狀態可能較具生理活性，FHY1會藉由磷酸化狀態的FIN219促進茉莉酸反應，誘導下游茉莉酸反應相關基因表現，造成下胚軸的生長受到抑制，同時也會促進ELONGATED HYPOCOTYL 5 (HY5) 在細胞核內的表現與累積，同樣造成短小下胚軸的外表型。另外，免疫共沉澱實驗結果顯示，FIN219在弱遠紅光下會與FHY1及phyA有交互作用。這些研究指出，FHY1可以促進受phyA磷酸化的FIN219穩定表現，促進光與茉莉酸的訊息反應，造成阿拉伯芥植物下胚軸的生長受到抑制。

Plants can detect the surrounding environmental signals and change their physiological metabolism, growth, and development accordingly. The interactions between light and various hormones are necessary for controlling plant photomorphogenesis. During the seedling stage, FAR-RED INSENSITIVE 219 (FIN219) participates in far-red (FR) light signal transduction regulated by phytochrome A (phyA) and is an important regulator involved in jasmonate responses. Far-Red Elongated Hypocotyl 1 (FHY1) is a positive regulator of FR light signal transduction and also plays a vital role in regulating nuclear accumulation and export of phyA. Previous studies showed the interaction between FIN219 and FHY1 under FR light. However, there are still some unclear points about the detailed molecular mechanisms underlying their relationships with JA. Here, we found that the presence of FHY1 promotes the accumulation of FIN219 phosphorylated by PHYA in the cytoplasm and that the phosphorylated FIN219 may be more physiologically active. FHY1 promotes jasmonic acid (JA) reaction and JA responsive gene expression through the phosphorylated FIN219 to enhance the inhibition of hypocotyl elongation. At the same time, it promotes the expression and accumulation of HY5 in the nucleus, leading to the short hypocotyl. In addition, Co-immunoprecipitation (Co-IP) data show that FIN219 interacts with FHY1 and PHYA under low far-red light. In summary, FHY1 can promote the stability of FIN219 phosphorylation by PHYA, induce the signal transduction of light and JA, and inhibit the growth of hypocotyls in Arabidopsis.