Arabidopsis AT-hook protein TEK positively regulates the expression of arabinogalactan proteins in controlling nexine layer formation in the pollen wall

Qi-Shi Jia; Jun Zhu; Xiao-Feng Xu; Yue Lou; Zhan-Lin Zhang; Zhi-Ping Zhang; Zhong-Nan Yang

doi:10.1093/mp/ssu114

Arabidopsis AT-hook protein TEK positively regulates the expression of arabinogalactan proteins in controlling nexine layer formation in the pollen wall

Mol Plant. 2014 Oct 20:ssu114. doi: 10.1093/mp/ssu114. Online ahead of print.

Authors

Qi-Shi Jia¹, Jun Zhu², Xiao-Feng Xu², Yue Lou², Zhan-Lin Zhang², Zhi-Ping Zhang³, Zhong-Nan Yang⁴

Affiliations

¹ College of Life and Environment Sciences, Shanghai Normal University, Shanghai, 200234, China College of Agriculture, Henan University of Science and Technology, Luoyang, 471003, China.
² College of Life and Environment Sciences, Shanghai Normal University, Shanghai, 200234, China.
³ National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.
⁴ College of Life and Environment Sciences, Shanghai Normal University, Shanghai, 200234, China znyang@shnu.edu.cn.

PMID: 25336567
DOI: 10.1093/mp/ssu114

Abstract

Nexine is a conserved layer of the pollen wall. We previously reported that the nexine layer is absent in the knockout mutant of TRANSPOSABLE ELEMENT SILENCING VIA AT-HOOK (TEK). In this work, we characterized the molecular function of TEK in pollen development and identified direct targets of TEK, Arabinogalactan proteins (AGPs), which are responsible for nexine formation. Electrophoretic mobility shift assay (EMSA) showed that TEK can directly bind to the nuclear matrix attachment region (MAR). Phenotypic similarity between tek and the TEK-SRDX transgenic lines indicated that TEK plays a role in transcriptional activation in anther development. Microarray analysis identified a total of 661 genes downstream of TEK, including four genes encoding AGPs, AGP6, AGP11, AGP23 and AGP40. Chromatin immunoprecipitation (ChIP) followed by PCR analysis using the FLAG-tagged TEK complement lines suggested that TEK is enriched in the promoters of these four genes. EMSA further confirmed that TEK binds to the AGP6 promoter. The expression of AGP6 driven by the TEK promoter in tek can partially rescue both nexine formation and plant fertility. These results show that TEK directly regulates AGPs expression in the anther. It is proposed that glycoproteins are an essential component of the nexine layer in the pollen wall.