SHI/STY Genes Affect Pre- and Post-meiotic Anther Processes in Auxin Sensing Domains in Arabidopsis.

Leandro H Estornell,Katarina Landberg,Eva Sundberg,Izabela Cierlik

doi:10.3389/fpls.2018.00150

Leandro H Estornell, Katarina Landberg + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2018.00150

Copy DOI

Abstract

In flowering plants, mature sperm cells are enclosed in pollen grains formed in structures called anthers. Several cell layers surrounding the central sporogenous cells of the anther are essential for directing the developmental processes that lead to meiosis, pollen formation, and the subsequent pollen release. The specification and function of these tissues are regulated by a large number of genetic factors. Additionally, the plant hormone auxin has previously been shown to play important roles in the later phases of anther development. Using the R2D2 auxin sensor system we here show that auxin is sensed also in the early phases of anther cell layer development, suggesting that spatiotemporal regulation of auxin levels is important for early anther morphogenesis. Members of the SHI/STY transcription factor family acting as direct regulators of YUC auxin biosynthesis genes have previously been demonstrated to affect early anther patterning. Using reporter constructs we show that SHI/STY genes are dynamically active throughout anther development and their expression overlaps with those of three additional downstream targets, PAO5, EOD3 and PGL1. Characterization of anthers carrying mutations in five SHI/STY genes clearly suggests that SHI/STY transcription factors affect anther organ identity. In addition, their activity is important to repress periclinal cell divisions as well as premature entrance into programmed cell death and cell wall lignification, which directly influences the timing of anther dehiscence and the pollen viability. The SHI/STY proteins also prevent premature pollen germination suggesting that they may play a role in the induction or maintenance of pollen dormancy.

Highlights

Stamens, the male reproductive organs in flowering plants, carry an apical anther and a basal filament transmitting water and nutrients from the shoot to the anther
SHI/STY Function in Arabidopsis Anthers lignification is instrumental in anther opening and pollen release; the middle layer (ML), which is important for pollen development, and the innermost layer, the tapetum, which is required for nourishment and development of the pollen (Esau, 1977; Pacini et al, 1985; Goldberg et al, 1993; Scott et al, 2004; Wilson et al, 2011; Fernández Gómez et al, 2015)
Our results reveal that auxin sensing is spatiotemporally controlled throughout anther development, including the pre-meiotic phase, and that SHI/STY genes are important in the control of processes regulated by auxin, as well as in processes not yet linked to auxin action

Summary

Introduction

The male reproductive organs in flowering plants, carry an apical anther and a basal filament transmitting water and nutrients from the shoot to the anther. The sporogenous tissue is surrounded by four somatic cell layers that contribute to the production and release of mature pollen grains carrying male gametes: the outermost cell layer, the epidermis; the endothecium, which upon. SHI/STY Function in Arabidopsis Anthers lignification is instrumental in anther opening and pollen release; the middle layer (ML), which is important for pollen development, and the innermost layer, the tapetum, which is required for nourishment and development of the pollen (Esau, 1977; Pacini et al, 1985; Goldberg et al, 1993; Scott et al, 2004; Wilson et al, 2011; Fernández Gómez et al, 2015). For a recent review of anther development and the different tissue layers, see Fernández Gómez et al (2015)

Objectives

Methods

Results

Discussion

Conclusion