State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Plant Physiol. 2013 Jul;162(3):1669-80. doi: 10.1104/pp.113.215673. Epub 2013 May 28.
Plant-specific TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors play crucial roles in development, but their functional mechanisms remain largely unknown. Here, we characterized the cellular functions of the class I TCP transcription factor GhTCP14 from upland cotton (Gossypium hirsutum). GhTCP14 is expressed predominantly in fiber cells, especially at the initiation and elongation stages of development, and its expression increased in response to exogenous auxin. Induced heterologous overexpression of GhTCP14 in Arabidopsis (Arabidopsis thaliana) enhanced initiation and elongation of trichomes and root hairs. In addition, root gravitropism was severely affected, similar to mutant of the auxin efflux carrier PIN-FORMED2 (PIN2) gene. Examination of auxin distribution in GhTCP14-expressing Arabidopsis by observation of auxin-responsive reporters revealed substantial alterations in auxin distribution in sepal trichomes and root cortical regions. Consistent with these changes, expression of the auxin uptake carrier AUXIN1 (AUX1) was up-regulated and PIN2 expression was down-regulated in the GhTCP14-expressing plants. The association of GhTCP14 with auxin responses was also evidenced by the enhanced expression of auxin response gene IAA3, a gene in the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) family. Electrophoretic mobility shift assays showed that GhTCP14 bound the promoters of PIN2, IAA3, and AUX1, and transactivation assays indicated that GhTCP14 had transcription activation activity. Taken together, these results demonstrate that GhTCP14 is a dual-function transcription factor able to positively or negatively regulate expression of auxin response and transporter genes, thus potentially acting as a crucial regulator in auxin-mediated differentiation and elongation of cotton fiber cells.
植物特有的 TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) 转录因子在发育过程中起着至关重要的作用，但它们的功能机制在很大程度上仍然未知。在这里，我们从陆地棉（Gossypium hirsutum）中鉴定了 I 类 TCP 转录因子 GhTCP14 的细胞功能。GhTCP14 主要在纤维细胞中表达，特别是在发育的起始和伸长阶段，其表达对外源生长素的反应增加。在拟南芥（Arabidopsis thaliana）中诱导异源过表达 GhTCP14 增强了毛状体和根毛的起始和伸长。此外，根向重力性受到严重影响，类似于生长素外排载体 PIN-FORMED2 (PIN2) 基因突变体。通过观察生长素反应报告基因，检查 GhTCP14 表达的拟南芥中的生长素分布，发现花萼毛状体和根皮层区域的生长素分布发生了很大变化。与这些变化一致，在 GhTCP14 表达的植物中，生长素摄取载体 AUXIN1 (AUX1) 的表达上调，PIN2 的表达下调。GhTCP14 与生长素反应的关联还表现在生长素反应基因 IAA3 的表达增强，IAA3 是 AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) 家族的一个基因。电泳迁移率变动分析显示，GhTCP14 结合了 PIN2、IAA3 和 AUX1 的启动子，转录激活分析表明 GhTCP14 具有转录激活活性。综上所述，这些结果表明 GhTCP14 是一种双重功能转录因子，能够正向或负向调节生长素反应和转运基因的表达，因此可能在生长素介导的棉花纤维细胞分化和伸长中发挥关键调控作用。
