The temporal regulation of TEK contributes to pollen wall exine patterning

by Shuang-Xi Xiong, Qiu-Ye Zeng, Jian-Qiao Hou, Ling-Li Hou, Jun Zhu, Min Yang, Zhong-Nan Yang, Yue Lou Pollen wall consists of several complex layers which form elaborate species-specific patterns. In Arabidopsis, the transcription factor ABORTED MICROSPORE (AMS) is a master regulator of exine formation, and another transcription factor, TRANSPOSABLE ELEMENT SILENCING VIA AT-HOOK (TEK), specifies f ormation of the nexine layer. However, knowledge regarding the temporal regulatory roles of TEK in pollen wall development is limited. Here, TEK-GFP driven by theAMS promoter was prematurely expressed in the tapetal nuclei, leading to complete male sterility in thepAMS:TEK-GFP (pat) transgenic lines with the wild-type background. Cytological observations in thepat anthers showed impaired callose synthesis and aberrant exine patterning.CALLOSE SYNTHASE5 (CalS5) is required for callose synthesis, and expression ofCalS5 inpat plants was significantly reduced. We demonstrated that TEK negatively regulatesCalS5 expression after the tetrad stage in wild-type anthers and further discovered that premature TEK-GFP inpat directly repressesCalS5 expression through histone modification. Our findings show that TEK flexibly mediates its different functions via different temporal regulation, revealing that the temporal regulation of TEK is essential for exine patterning. Moreover, the result that the repression ofCalS5 by TEK after the tetrad stage coincides with the timing of callose wall diss...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research