A brassinolide-suppressed rice MADS-box transcription factor, OsMDP1, has a negative regulatory role in BR signaling
A brassinolide-suppressed rice MADS-box transcription factor, OsMDP1, has a negative regulatory role in BR signaling
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DOI：
10.1111/j.1365-313x.2006.02804.x
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发表时间：
2006-08-01
期刊：
影响因子：
7.2
通讯作者：
Xue, Hong-Wei
中科院分区：
文献类型：
--
作者：
Duan, Ke;Li, Li;Xue, Hong-Wei
MADS-box转录因子编码基因主要在植物生殖发育过程中表达，在控制花器官的发生和分化中发挥重要作用。以前很少有报道研究营养组织中表达的MADS盒转录因子的功能。在这里，我们描述了一个水稻AG样MADS盒蛋白，OsMDP 1（水稻MADS结构域包含蛋白1）的功能特性。通过高通量筛选水稻油菜素内酯调控基因，获得了编码MADS-box结构域的部分cDNA，并通过筛选水稻分蘖期cDNA文库，获得了全长cDNA。表达谱分析表明，OsMDP 1主要在成熟叶片、胚芽鞘、根伸长区、茎节间等营养组织中表达，尤其是在叶鞘与叶片的连接部位。进一步的研究表明OsMDP 1的转录受黑暗刺激，而受油菜素处理的抑制。OsMDP 1缺失导致幼根缩短、胚芽鞘延长、叶片连接倾斜度增加。此外，转基因植株表现出对外源油菜素的超敏感性，表现在叶片关节倾斜和胚芽鞘伸长。OsMDP 1缺陷导致OsXTR 1的表达增强，OsXTR 1编码木葡聚糖内糖基转移酶，细胞伸长所必需的细胞壁疏松酶，并调节参与细胞信号传导和基因转录的多个基因的表达，表明OsMDP 1在BR信号传导中的关键负调控作用。
The MADS-box transcription factor-encoding genes are expressed mainly during plant reproductive development, where they play important roles in controlling floral organ initiation and identity. Few previous reports have investigated the functions of MADS-box transcription factors expressed in vegetative tissues. Here we describe the functional characterization of a rice AG-like MADS-box protein, OsMDP1 (Oryza sativa MADS-domain-containing protein 1). A partial cDNA encoding a MADS-box domain was identified via high-throughput screening of rice brassinolide-regulated genes, and the full-length cDNA was subsequently isolated via screening of a cDNA library constructed from rice materials at tillering stage. Expression pattern analyses indicated that OsMDP1 is transcribed mainly in vegetative tissues, including the mature leaf, coleoptile, root-elongation zone, culm internode, and especially the joint region between the leaf blade and sheath. Further studies revealed that transcription of OsMDP1 is stimulated by darkness and suppressed by brassinolide treatment. OsMDP1 deficiency resulted in shortened primary roots, elongated coleoptiles and enhanced lamina joint inclinations. Moreover, transgenic plants showed hypersensitivities to exogenous brassinolide in terms of lamina joint inclination and coleoptile elongation. OsMDP1 deficiency resulted in enhanced expression of OsXTR1, which encodes xyloglucan endotransglycosylase, the cell-wall loosening enzyme necessary for cell elongation, and modulated expressions of multiple genes involved in cell signalling and gene transcription, indicating the key negative regulatory role of OsMDP1 in BR signalling.