EREBP/AP2-type proteins are members of a large DNA binding protein (DBP) family found in plants. Some members like APETALA2 and AtDREB/CBF can regulate flower development and response to environmental stresses, respectively. To characterize transcription factors involved in plant responses to salt stress, we constructed cDNA library from salt-treated halophyte (Atriplex hortensis) and isolated a novel gene encoding EREBP/AP2-type protein from this library. This cDNA contained an ORF of 723 bp and a long 3'-Untranslated-Region (UTR) of 655 bp. The deduced amino acid sequence showed one conserved DNA binding domain of EREBP/AP2, thus the corresponding gene was named AhDREB1 with a calculated molecular mass of 26.1 kD. AhDREB1 under the control of CaMV 35S promoter was then transformed into tobacco and nine independent transgenic lines were obtained and subjected to long term salt stress. The results suggested that overexpression of AhDREB1 improved the salt tolerance in transgenic tobacco through functioning as a regulatory molecule in response to salt stress. Analysis of Arabidopsis genome in database resulted in dozens of EREBP/AP2-type homologous proteins, of which seven members showed high similarity to AhDREB1. Secondary structure analysis predicted similar arrangement of a-helix in their DNA binding domains.
丝裂原活化蛋白激酶(M APK)是生物体内信号转导的重要组分,与生长、发育和逆境胁迫反应密切相关.为了研究草坪草对非生物逆境胁迫反应的分子机理,利用同源基因克隆法从4℃低温诱导的草坪草高羊茅(F estu-ca arund inacea Schreb.)幼苗cDNA文库中分离得到一个M APK的cDNA即F aMAPK 1,F aMAPK 1编码369个氨基酸残基的蛋白激酶,该蛋白激酶具有TEY的磷酸化基序.据推测的氨基酸序列的BLA ST同源性分析表明,F aM APK 1蛋白与水稻O sM APK 4蛋白的一致性为91.1%.N orthern杂交检测F aMAPK 1基因对逆境胁迫反应的结果表明冷(4℃)处理对根中F aMAPK 1基因的表达没有明显影响,但诱导叶中F aMAPK 1上调表达.而且低温(4℃)、高盐(250 mm o l/L N aC l)、干旱和100μm o l/L ABA都诱导叶中F aMAPK 1上调表达,表明F aM APK 1蛋白可能在高羊茅对非生物逆境胁迫的反应中起重要作用.
