Arabidopsis AT-hook Protein TEK Positively Regulates the Expression of Arabinogalactan Proteins for Nexine Formation
Arabidopsis AT-hook Protein TEK Positively Regulates the Expression of Arabinogalactan Proteins for Nexine Formation
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DOI：
10.1016/j.molp.2014.10.001
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发表时间：
2015-02-02
期刊：
影响因子：
27.5
通讯作者：
Yang, Zhong-Nan
中科院分区：
文献类型：
--
作者：
Jia, Qi-Shi;Zhu, Jun;Yang, Zhong-Nan
Nexine是花粉壁的一个保守层。我们先前报道了拟南芥转座子沉默通过AT-HOOK（TEK）基因敲除突变体中的nexine层缺失。在这项研究中，我们研究了TEK在花粉发育中的分子调控功能，并确定了编码阿拉伯半乳聚糖蛋白（AGPs）的基因作为TEK的直接靶点，这是nexine形成所必需的。TEK和TEK-SRDX转基因株系之间的表型相似性表明TEK在花药发育中的转录激活中起作用。微阵列分析共鉴定出661个tek下调基因，包括4个编码AGPs的基因，AGP 6、AGP 11、AGP 23和AGP 40。电泳迁移率变动分析表明，TEK可以直接结合核基质附着区（MAR）和AGP 6的启动子。染色质免疫沉淀PCR分析表明，TEK是丰富的四个AGP基因的启动子。TEK启动子驱动的AGP 6在tek中的表达部分地拯救了连接蛋白的形成和植物的育性。这些结果表明TEK直接调节花药中AGP的表达以控制连结层的形成。我们还提出，糖蛋白可能是花粉壁中连结层的重要组成部分。
Nexine is a conserved layer of the pollen wall. We previously reported that the nexine layer is absent in the knockout mutant of Arabidopsis TRANSPOSABLE ELEMENT SILENCING VIA AT-HOOK (TEK) gene. In this study, we investigated the molecular regulatory functions of TEK in pollen development and identified the genes encoding Arabinogalactan proteins (AGPs) as direct targets of TEK, which are essential for nexine formation. Phenotypic similarity between tek and the TEK-SRDX transgenic lines suggest that TEK plays a role in transcriptional activation in anther development. Microarray analysis identified a total of 661 genes downregulated in tek, including four genes encoding AGPs, AGP6, AGP11,AGP23, and AGP40. Electrophoretic mobility shift assays showed that TEK could directly bind the nuclear matrix attachment region (MAR) and the promoter of AGP6. Chromatin immunoprecipitation followed by PCR analysis demonstrated that TEK is enriched in the promoters of the four AGP genes. Expression of AGP6 driven by the TEK promoter in tek partially rescued both nexine formation and plant fertility. These results indicate that TEK directly regulates AGP expression in the anther to control nexine layer formation. We also proposed that glycoproteins might be essential components of the nexine layer in the pollen wall.