BACKGROUND Modification of root architecture and improvement of root resistance to stresses can increase crop productivity. Functional analyses of root-specific genes are necessary for root system improvement, and root-specific promoters enable research into the regulation of root development and genetic manipulation of root traits. Maize is an important crop species; however, little systematic mining of root-specific genes and promoters has been performed to date. RESULTS Genomic-scale mining based on microarray data sets followed by transcript detection resulted in the identification of 222 root-specific genes. Gene Ontology enrichment analyses revealed that these 222 root-specific genes were mainly involved in responses to chemical, biotic, and abiotic stresses. Of the 222 genes, 33 were verified by quantitative reverse transcription polymerase chain reaction, and 31 showed root-preferential activity. About 2 kb upstream 5 of the 31 identified root-preferential genes were cloned from the maize genome as putative promoters and named p8463, p5023, p1534, p8531 and p6629. GUS staining of transgenic maize-derived promoter-GUS constructs revealed that the five promoters drove GUS expression in a root-preferential manner. CONCLUSIONS We mined root-preferential genes and their promoters in maize and verified p8463, p5023, p1534, p8531 and p6629 as root-preferential promoters. Our research enables the identification of other tissue-specific genes and promoters in maize and other species. In addition, the five promoters may enable enhancement of target gene(s) of maize in a root-preferential manner to generate novel maize cultivars with resistance to water, fertilizer constraints, or biotic stresses.

中文翻译：

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玉米根偏好基因的基因组规模挖掘及其启动子活性的表征。

背景技术根结构的改变和根对胁迫的抗性的提高可以提高作物生产力。根特异性基因的功能分析对于根系改良是必要的，根特异性启动子使得研究根发育的调控和根性状的遗传操作成为可能。玉米是重要的农作物品种；然而，迄今为止，对根特异性基因和启动子的系统挖掘还很少。结果基于微阵列数据集的基因组规模挖掘以及转录本检测鉴定出 222 个根特异性基因。基因本体富集分析表明，这 222 个根特异性基因主要参与对化学、生物和非生物胁迫的响应。在222个基因中，33个通过定量逆转录聚合酶链反应得到验证，31个显示出根部优先活性。在上游约 2 kb 处，从玉米基因组中克隆了 31 个已鉴定的根优先基因中的 5 个作为推定启动子，并命名为 p8463、p5023、p1534、p8531 和 p6629。对转基因玉米衍生的启动子-GUS 构建体的 GUS 染色表明，这五个启动子以根优先的方式驱动 GUS 表达。结论 我们在玉米中挖掘了根优先基因及其启动子，并验证了 p8463、p5023、p1534、p8531 和 p6629 为根优先启动子。我们的研究能够鉴定玉米和其他物种中的其他组织特异性基因和启动子。此外，这五个启动子可以以根优先的方式增强玉米的靶基因，以产生具有抗水、肥料限制或生物胁迫的新型玉米品种。