受阿拉伯芥FIN219調控的ERFs在滲透壓與鹽害逆境下的功能性研究

Abstract

為了適應環境，植物會發展出各種防禦機制包括利用植物荷爾蒙來抵禦逆境。在非生物逆境如鹽害和乾旱逆境下，離層酸是主要調控植物防禦反應的植物荷爾蒙，而茉莉酸以及乙烯也會參與其中。FIN219 (FAR-RED INSENSITIVE 219)也被稱作為JAR1 (JASMONIC ACID RESISTANT 1)，是一個合成結合形式茉莉酸的酵素，會使茉莉酸接上異白氨酸而產生具有活性的茉莉酸，在實驗室先前的微陣列分析數據指出，部分ERF (ETHYLENE RESPONSIVE FACTOR) 轉錄因子會被FIN219/JAR1所調控，而ERFs主要參與在逆境調控途徑中。這些資料指出FIN219可能是藉由調控ERFs來參與鹽害和乾旱逆境。此外，HY5 (ELONGATED HYPOCOTYL 5) 則被報導指出會與ERF4及ERF11的啟動子結合，顯示了HY5參與FIN219-ERF訊息傳遞的可能性。本研究結果顯示，hy5突變株對滲透壓及鹽逆境處理較敏感且其FIN219的蛋白質含量會受到影響。此外，在離層酸處理下會誘導HY5和ERF15的mRNA表現量以及FIN219的蛋白質表現量。這些結果與表現型分析結果顯示FIN219-HY5-ERF的訊息傳遞在逆境中是透過離層酸所調控。另一方面，我們建構了大量表現HY5以及ERFs的轉殖株以檢驗兩者在逆境下所參與的生理功能，發現ERF11負調控而ERF15正調控植物對滲透壓與鹽逆境的耐受性。在Co-immunoprecipitation (Co-IP)分析中顯示HY5與ERF15具有蛋白質間的交互作用。綜合上述結果，我們推測阿拉伯芥在滲透壓與鹽逆境下會受到FIN219-HY5-ERF的訊息傳遞途徑所調控。

Plants have developed various defense mechanisms, including using phytohormones to adapt stress conditions. Under abiotic stresses such as drought and salt stress, abscisic acid (ABA) is the major phytohormone in regulating the stress tolerance of plants. In addition to ABA, jasmonic acid (JA) and ethylene also participate in drought and salt stress responses. FIN219 (FAR-RED INSENSITIVE 219), also known as JAR1 (JASMONIC ACID RESISTANT 1), is an enzyme that conjugates JA with isoleucine (Ile) and leads to the formation of JA-Ile, an active form of JA. Our previous microarray data showed that several ERF (ETHYLENE RESPONSIVE FACTOR) transcription factors were affected by FIN219/JAR1. Moreover, ERFs mainly functioned in stress responses. These findings imply that FIN219 may participate in osmotic and salt stress responses through regulating ERFs. Besides, HY5 (ELONGATED HYPOCOTYL 5) has been reported to bind to the promoters of ERF4 and ERF11, which suggests the involvement of HY5 in the FIN219-ERF signaling network. This study shows that the mutation of HY5 decreases the resistance of plants to salt and drought stresses and affects the levels of FIN219. Moreover, HY5 and ERF15 mRNA levels and FIN219 protein levels increase under ABA treatment. It seems that the FIN219-HY5-ERF signaling network is regulated by ABA under stresses since their protein levels and phenotypes are influenced by ABA, salt and mannitol treatments. On the other hand, we further establish the inducible HY5 and ERFs overexpression (OE) lines to examine their physiological functions under stresses. The results indicate that ERF11 negatively and ERF15 positively regulates osmotic and salt stresses tolerance of plants. Further co-immunoprecipitation (Co-IP) assay shows that protein-protein interaction exists between HY5 and ERF15. In conclusion, our work reveals that the FIN219-HY5-ERF signaling may serve as a module to regulate stress responses in Arabidopsis.