The AP2/EREBP transcription factors play important roles in plant development and in the responses of plants to biotic and abiotic stresses. All members of the EREBP subfamily described to date are from dicotyledonous plants. In this paper, we describe the cloning and characterization of a rice gene, OsEBP-89, encoding a protein 326 amino acids long with a typical EREBP domain; this is the first report of an EREBP transcription factor in a monocotyledonous plant. Except for the EREBP domain, the OsEBP-89 protein does not have substantial sequence similarities to other members of the subfamily. The DNA-binding activity of the EREBP domain was confirmed by electrophoretic mobility-shift assays. An activation domain rich in acidic amino acids was identified by using a yeast one-hybrid system. Two putative nuclear-localization signals were also identified. The results of northern blot hybridization experiments showed that the transcript of the OsEBP-89 gene accumulates primarily in immature seeds, roots, and leaves (low levels). More detailed information about the pattern of OsEBP-89gene expression was obtained by histochemical studies of transgenic rice plants carrying an OsEBP-89 5'/GUS reporter gene. The reporter gene was expressed in the endosperm starting at 7 days after pollination and in the intercalary meristem of plants. Expression of OsEBP-89was induced in roots of rice seedlings by treatment with ACC, NaCl, or 2,4-D. Two cis-acting elements, an endosperm motif and a primary PERE, are present upstream of the OsEBP-89 coding region and may be involved in regulating its expression. Collectively, these results suggest that the OsEBP-89gene is a new member of the EREBP subfamily and may be involved in ethylene-dependent seed maturation and shoot development of rice.
AP2/EREBP轉(zhuǎn)錄因子在植物發(fā)育和應(yīng)對生物、非生物脅迫的過程中發(fā)揮著重要的作用。目前對EREBP蛋白亞家族的分析都是在雙子葉植物中展開的。本研究作者對水稻中一個基因OsEBP-89進行了克隆和分析，該基因編碼一個326個氨基酸組成，具有典型EREBP結(jié)構(gòu)域的蛋白。這是對單子葉中EREBP轉(zhuǎn)錄因子的首次報道。除了EREBP結(jié)構(gòu)域外，OsEBP-89與亞家族的其他成員沒有序列上的相似性。通過凝膠遷移速率變化的分析，對EREBP結(jié)構(gòu)域的DNA結(jié)合活性進行了驗證。通過酵母單雜交鑒定出一個富含酸性氨基酸的激活結(jié)構(gòu)域。另外還鑒定出兩個推測的核定位信號。Northern雜交結(jié)果表明OsEBP-89主要在未成熟種子、根和葉片（較低葉片）中表達。通過構(gòu)建OsEBP-89 5'/GUS報告基因的轉(zhuǎn)基因植株，對OsEBP-89詳細(xì)的表達模式進行了組織化學(xué)分析。報告基因在授粉后7d的胚乳中和居間分生組織中表達。OsEBP-89在幼苗根中的表達受到ACC、NaCl和2,4-D 處理誘導(dǎo)。在OsEBP-89 編碼區(qū)的上游具有兩個順式作用元件（一個胚乳基序和一個主要的PERE），它們可能參與了對OsEBP-89 的表達調(diào)控。這些結(jié)果表明OsEBP-89 基因是EREBP家族的一個新成員，可能參與了水稻依賴乙烯的種子成熟和地上部發(fā)育過程。