title: Arabidopsis AT-hook protein TEK positively regulates the expression of arabinogalactan proteins for Nexine formation.
abstract: 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.
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China; College of Agriculture, Henan University of Science and Technology, Luoyang 471003, China.
authors.forename: Qi-Shi
authors.initials: QS
authors.lastname: Jia
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China.
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Xu
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Lou
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China.
authors.forename: Zhan-Lin
authors.initials: ZL
authors.lastname: Zhang
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Zhang
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China. Electronic address: znyang@shnu.edu.cn.
authors.forename: Zhong-Nan
authors.initials: ZN
authors.lastname: Yang
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D009088:Mucoproteins / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D011058:Pollen / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins
keywords: cell walls; development; nexine; pollen development