阿拉伯芥FIN219與MADS-box轉錄因子FUL間交互作用對參與在光與茉莉酸訊息傳遞路徑中的功能性探討

Abstract

植物對環境因子像光和植物激素的刺激做出反應，以維持生長的恆定性並調節其發育。光是植物的重要環境訊息，而茉莉酸(jasmonates, JA)也參與在生長發育調控，包括光形態發生(photomorphogenesis)。儘管了解光與茉莉酸訊息傳遞途徑的調控網絡相當重要，但關於兩者的整合機制仍有待深入研究。FAR-RED INSENSITIVE 219/JASMONIC ACID RESISTANT 1 (FIN219/JAR1)被發現不僅參與phyA和CRY1的光訊息傳遞途徑中，還可將JA與異亮氨酸(isoleucine)結合而參與在JA反應。先前研究發現番茄中，藍光和JRL1 (JAR1-like)能上調MADS-box轉錄因子TDR4/FUL1，以促進JA反應和果實成熟。然而，關於FIN219與其在阿拉伯芥中的同源基因FRUITFULL (FUL)的關係研究偏少。本研究發現，FIN219和FUL對開花時間、果莢延長及種子發育有相反的調控方式。光和茉莉酸介導的下胚軸抑制實驗顯示FUL可能是光形態發生的負調控因子，而FIN219在調控下胚軸延長的抑制性方面對FUL具有上位性(epistasis)的關係。雙分子螢光互補實驗證實，FUL與FIN219在MeJA和不同光處理下都有交互作用，且FIN219和MeJA會影響FUL形成二聚體。此外，雙冷光素酶報告基因轉錄活性測試顯示，FUL可以通過活化FIN219啟動子來上調它的表達，而JAZ1則在果莢發育過程中受到FUL抑制。總之，本研究揭示了FUL與FIN219通過相互作用及轉錄調控，實現光與JA訊息傳遞途徑之間的潛在分子機制，從而協同調控幼苗和生殖階段的生長與發育。

Plants respond to environmental stimuli like light and phytohormones to maintain homeostasis and regulate development. Light is a crucial environmental signal, while jasmonates (JAs) also contribute to developmental regulation, including photomorphogenesis. Despite the importance of understanding the upstream regulation networks of light and JA signaling pathways, their integration remains underexplored. FAR-RED INSENSITIVE 219/JASMONIC ACID RESISTANT 1 (FIN219/JAR1) participates in both phyA and CRY1 light signaling and JA responses because of its enzymatic function to conjugate JA-Ile. Previously, blue light and JRL1 (JAR1-like) activated TDR4/FUL1, a MADS-box transcription factor, to promote JA responses and fruit ripening in tomato. However, little research has elucidated the relationship between FIN219 and FRUITFULL (FUL), a TDR4 homolog in Arabidopsis. Here, FIN219 and FUL present opposite effects on flowering, silique elongation, and seed development. Meanwhile, hypocotyl inhibition suggests that FUL might act as a negative regulator in photomorphogenesis, with FIN219 being epistatic to FUL. Bimolecular Fluorescence Complementation (BiFC) and Luciferase complementation imaging (LCI) assays confirm that the interaction between FUL and FIN219 happened under MeJA and different light treatments, while FIN219 and MeJA influence FUL dimerization. Furthermore, Dual-LUC transactivation assays reveal that FUL upregulates FIN219 expression by activating its promoter, and JAZ1 is suppressed in the silique. In summary, this study unveils possible crosstalk between light and JA signaling pathways through FUL and FIN219 interactions and transcriptional regulation, thus collaborating to govern seedling and reproductive development.