"乙烯反應因子19與NINJA抑制子複合體交互作用,負調控阿拉伯芥對於灰黴菌的防禦反應"

Abstract

Ethylene response factors (ERFs)的轉錄因子已經被證實參與在阿拉伯芥(Arabidopsis thaliana)的生長發育以及防禦反應中。在本研究中，我們發現了一個未被報道的ERF轉錄因子19。它是一個可能結合在啟動子區的GCC序列上的轉錄因子，並且能夠負調控阿拉伯芥對於灰黴菌的防禦反應。大量表現ERF19會降低茉莉酸防禦反應的標誌基因PDF1.2a和PR3的基因表現，并使植株對於灰黴菌更加感病。儘管在原生質體轉化實驗(protoplast transactivation assay)中發現, ERF19是轉錄上的激活因子，但是在生物體內的bimolecular fluorescence complementation實驗和co-immunoprecipitation實驗結果表明ERF19和NINJA抑制子以及组蛋白脱乙酰酶HDA6，HDA19複合體交互作用。此外原生質體轉化實驗表明ERF19的轉錄活性被NINJA顯著性的抑制了。因此，我們猜測ERF19通過與NINJA抑制子複合體交互作用負調控茉莉酸反應。我們的實驗結果闡述了ERF19介導的一個新的轉錄抑制機制。

Arabidopsis ethylene response factors (ERFs) are known to be involved in various developmental and defense processes. Here, we report novel mechanisms of ERF19, a potential GCC box binding transcription factor, to negatively regulate defense response against the fungal pathogen Botrytis cinerea. Over-expression of ERF19 leads to increased Arabidopsis susceptibility to B. cinerea via repressing the induction of jasmonic acid (JA) defense marker genes PDF1.2a and PR3. Although ERF19 acted as activator of transcription in protoplast transactivation assay (PTA), in vivo bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) assays revealed that ERF19 associates with the transcriptional repressor NINJA and histone deacetylases HDA6 and HDA19. Moreover, ERF19 activity were significantly repressed by NINJA in PTA assay. We proposed that ERF19 recruits the NINJA repressor complex to negatively regulate JA-mediated defense responses. Our results provide new insights into the mechanisms of ERF19-mediated transcriptional repression.