阿拉伯芥中 FIN219 與 COI1 的交互作用在遠紅光與茉莉酸訊息傳遞中的功能性研究

Abstract

阿拉伯芥中 FAR-RED INSENSIVIVE 219 (FIN219)/JASMONATE RESISTANT 1 (JAR1)與 CORONATINE INSENSITIVE 1 (COI1)是茉莉酸訊息傳遞中兩個正 向調控因子。FIN219/JAR1 催化茉莉酸鍵結上異亮氨酸,而形成具有生理活性的 茉莉酸衍生物,此衍生物為SFCCOI1與JASMONATE-ZIM-DOMAIN PROTEINs (JAZs)結合的配合體,進而促成茉莉酸訊息傳遞抑制者 JAZs 降解。近期的文 獻指出 FIN219 與 COI1 都參與遠紅光訊息傳遞,此研究立基於釐清倆者在遠紅 光訊息傳遞以及茉莉酸訊息傳遞中的調控關係。我們發現 FIN219 與 COI1 在調 控不稔性以及對遠紅光的敏感性上,有加成性的效果;但 FIN219 大量表現造成 的短下胚軸性狀會被 COI1 大量表現抑制。以大腸桿菌表現倆者蛋白質的方式與 酵母菌雙雜合實驗的結果都顯示倆者可互相結合;在阿拉伯芥的原生質體中,倆 者共同坐落在細胞核內。藉由篩選極研究各種大量表現 FLAG-COI1 的轉殖株, 因而發現茉莉酸的感知及訊息傳遞會促進 COI1 的累積,但是 FIN219 卻對此有 抑制的效果。在遠紅光下,COI1 大量表現可以抑制 fin219-2 突變株具有較長下 胚軸的性狀;此外,外加茉莉酸後,倆者可以透過獨立於彼此的方式,促成 HY5 的累積。在以上實驗中,我們呈現 FIN219 與 COI1 在遠紅光及茉莉酸訊息傳導 中相互調控的關係,顯示出訊息傳導中調校與交互作用的現象。

In Arabidopsis, FAR-RED INSENSIVIVE 219 (FIN219)/JASMONATE RESISTANT 1 (JAR1) and CORONATINE INSENSITIVE 1 (COI1) are positive regulators in jasmonate (JA) signaling. FIN219/JAR1 catalyzes the synthesis of JA-isoleucine (JA-Ile), which is a bioactive conjugate of JA that promotes the binding of SFCCOI1 and JASMONATE-ZIM-DOMAIN PROTEINs (JAZs). This binding results in the degradation of JA signaling repressors JAZs by 26S proteasome. Recent publications indicate that both FIN219 and COI1 are involved in phytochrome A mediated high irradiance response during seedling de-etiolation. This study aimed to elucidate the relation of FIN219 and COI1 in FR light and JA signaling. We found that FIN219 and COI1 synergistically regulate fertility and FR light sensitivity. However, COI1 overexpression may suppress the effect of FIN219 overexpression on hypocotyl growth by post-transcriptional regulation. The results of pull-down and yeast two-hybrid assays suggest that FIN219 and COI1 may interact. We also showed both proteins can co-localize in the nuclei of Arabidopsis protoplasts. By generating FLAG-COI1 overexpression plants, we showed that JA perception/signaling promotes COI1 accumulation, whereas FIN219 represses this phenomenon. In FR light, COI1 overexpression suppressed fin219-2 long-hypocotyl phenotype. Both FIN219 and COI1 contribute to HY5 accumulation upon JA activation in FR light, which FIN219 and COI1 may exert their function synergistically. Taken together, the regulatory relationship of FIN219 and COI1 is fine-tuningly modulated and has a crosstalk between FR light and JA signalings.