School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449-728, Korea.
Plant Physiol. 2010 May;153(1):185-97. doi: 10.1104/pp.110.154773. Epub 2010 Mar 24.
Drought poses a serious threat to the sustainability of rice (Oryza sativa) yields in rain-fed agriculture. Here, we report the results of a functional genomics approach that identified a rice NAC (an acronym for NAM [No Apical Meristem], ATAF1-2, and CUC2 [Cup-Shaped Cotyledon]) domain gene, OsNAC10, which improved performance of transgenic rice plants under field drought conditions. Of the 140 OsNAC genes predicted in rice, 18 were identified to be induced by stress conditions. Phylogenic analysis of the 18 OsNAC genes revealed the presence of three subgroups with distinct signature motifs. A group of OsNAC genes were prescreened for enhanced stress tolerance when overexpressed in rice. OsNAC10, one of the effective members selected from prescreening, is expressed predominantly in roots and panicles and induced by drought, high salinity, and abscisic acid. Overexpression of OsNAC10 in rice under the control of the constitutive promoter GOS2 and the root-specific promoter RCc3 increased the plant tolerance to drought, high salinity, and low temperature at the vegetative stage. More importantly, the RCc3:OsNAC10 plants showed significantly enhanced drought tolerance at the reproductive stage, increasing grain yield by 25% to 42% and by 5% to 14% over controls in the field under drought and normal conditions, respectively. Grain yield of GOS2:OsNAC10 plants in the field, in contrast, remained similar to that of controls under both normal and drought conditions. These differences in performance under field drought conditions reflect the differences in expression of OsNAC10-dependent target genes in roots as well as in leaves of the two transgenic plants, as revealed by microarray analyses. Root diameter of the RCc3:OsNAC10 plants was thicker by 1.25-fold than that of the GOS2:OsNAC10 and nontransgenic plants due to the enlarged stele, cortex, and epidermis. Overall, our results demonstrated that root-specific overexpression of OsNAC10 enlarges roots, enhancing drought tolerance of transgenic plants, which increases grain yield significantly under field drought conditions.
干旱对雨养农业中水稻（Oryza sativa）产量的可持续性构成严重威胁。在这里，我们报告了功能基因组学方法的结果，该方法鉴定了一个水稻 NAC（NAM[无顶芽]、ATAF1-2 和 CUC2[杯状子叶]）结构域基因 OsNAC10，该基因可提高转基因水稻在田间干旱条件下的表现。在水稻中预测的 140 个 OsNAC 基因中，有 18 个被鉴定为受胁迫条件诱导。对 18 个 OsNAC 基因的系统发育分析表明，存在具有不同特征基序的三个亚组。对一组 OsNAC 基因进行了预筛选，以确定其在过表达时对胁迫的耐受性增强。从预筛选中选择的有效成员之一 OsNAC10，主要在根和穗中表达，并受干旱、高盐和脱落酸诱导。在组成型启动子 GOS2 和根特异性启动子 RCc3 的控制下，在水稻中过表达 OsNAC10，可提高植物在营养阶段对干旱、高盐和低温的耐受性。更重要的是，RCc3:OsNAC10 植株在生殖阶段表现出明显的耐旱性，在田间干旱和正常条件下，与对照相比，分别增加了 25%至 42%和 5%至 14%的粒产量。相比之下，GOS2:OsNAC10 植株在田间的粒产量在正常和干旱条件下与对照相似。这些在田间干旱条件下表现的差异反映了两个转基因植物根系以及叶片中 OsNAC10 依赖的靶基因表达的差异，这是通过微阵列分析揭示的。RCc3:OsNAC10 植株的根直径比 GOS2:OsNAC10 和非转基因植株的根直径大 1.25 倍，这是由于茎、皮层和表皮增大所致。总的来说，我们的结果表明，OsNAC10 的根特异性过表达会增大根系，从而增强转基因植物的耐旱性，从而在田间干旱条件下显著提高粒产量。
