Nakashima Kazuo, Jan Asad, Todaka Daisuke, Maruyama Kyonoshin, Goto Shingo, Shinozaki Kazuo, Yamaguchi-Shinozaki Kazuko
Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki, 305-8686, Japan,
Planta. 2014 Jan;239(1):47-60. doi: 10.1007/s00425-013-1960-7. Epub 2013 Sep 24.
Rice production is greatly affected by environmental stresses such as drought and high salinity. Transgenic rice plants tolerant to such stresses are expected to be produced. Stress-responsive promoters with low expression under normal growth conditions are needed to minimize the adverse effects of stress-tolerance genes on rice growth. We performed expression analyses of drought-responsive genes in rice plants using a microarray, and selected LIP9, OsNAC6, OsLEA14a, OsRAB16D, OsLEA3-1, and Oshox24 for promoter analysis. Transient assays using the promoters indicated that AREB/ABF (abscisic acid (ABA)-responsive element-binding protein/ABA-binding factor) transcription factors enhanced expressions of these genes. We generated transgenic rice plants containing each promoter and the β-glucuronidase (GUS) reporter gene. GUS assays revealed that the LIP9 and OsNAC6 promoters were induced by drought, high salinity, and ABA treatment, and both promoters showed strong activity under normal growth conditions in the root. The other promoters were strongly induced by stresses and ABA, but showed low activity under normal growth conditions. In seeds, GUS staining showed that Oshox24 expression was low and expressions of the other genes were high. Transgenic rice plants overexpressing OsNAC6 under the control of the Oshox24 promoter showed increased tolerance to drought and high salinity, and no growth defects. These data suggest that the Oshox24 promoter is useful to overexpress stress-tolerance genes without adversely affecting growth.
水稻生产受到干旱和高盐度等环境胁迫的极大影响。人们期望培育出能耐受此类胁迫的转基因水稻植株。需要在正常生长条件下低表达的胁迫响应启动子，以尽量减少胁迫耐受基因对水稻生长的不利影响。我们利用微阵列对水稻植株中的干旱响应基因进行了表达分析，并选择了LIP9、OsNAC6、OsLEA14a、OsRAB16D、OsLEA3-1和Oshox24进行启动子分析。使用这些启动子的瞬时分析表明，脱落酸（ABA）响应元件结合蛋白/ABA结合因子（AREB/ABF）转录因子增强了这些基因的表达。我们培育了含有每个启动子和β-葡萄糖醛酸酶（GUS）报告基因的转基因水稻植株。GUS分析显示，LIP9和OsNAC6启动子受干旱、高盐度和ABA处理诱导，且在正常生长条件下，这两个启动子在根中均表现出强活性。其他启动子受胁迫和ABA强烈诱导，但在正常生长条件下活性较低。在种子中，GUS染色显示Oshox24表达较低，其他基因表达较高。在Oshox24启动子控制下过表达OsNAC6的转基因水稻植株对干旱和高盐度的耐受性增强，且无生长缺陷。这些数据表明，Oshox24启动子可用于过表达胁迫耐受基因而不对生长产生不利影响。
