Auxin polar transport in stamen formation and development: how many actors?

Maura Cardarelli,Valentina Cecchetti

doi:10.3389/fpls.2014.00333

Abstract

In flowering plants, proper development of stamens, the male reproductive organs, is required for successful sexual reproduction. In Arabidopsis thaliana normally six stamen primordia arise in the third whorl of floral organs and subsequently differentiate into stamen filaments and anthers, where male meiosis occurs, thus ending the early developmental phase. This early phase is followed by a late developmental phase, which consists of a rapid elongation of stamen filaments coordinated with anther dehiscence and pollen maturation, and terminates with mature pollen grain release at anthesis. Increasing evidence suggests that auxin transport is necessary for both early and late phases of stamen development. It has been shown that different members of PIN (PIN-FORMED) family are involved in the early phase, whereas members of both PIN and P-glycoproteins of the ABCB (PGP) transporter families are required during the late developmental phase. In this review we provide an overview of the increasing knowledge on auxin transporters involved in Arabidopsis stamen formation and development and we discuss their role and functional conservation across plant species.

Highlights

Stamens are the male reproductive structure of flowers and their function is to produce pollen grains, which house male gametes, and to release them at flower opening to allow plant reproduction
It has been shown that different members of PIN (PIN-FORMED) family are involved in the early phase, whereas members of both PIN and P-glycoproteins of the ATP Binding Cassette subfamily B (ABCB) (PGP) transporter families are required during the late developmental phase
In this review we provide an overview of the increasing knowledge on auxin transporters involved in Arabidopsis stamen formation and development and we discuss their role and functional conservation across plant species

Summary

INTRODUCTION

Stamens are the male reproductive structure of flowers and their function is to produce pollen grains, which house male gametes, and to release them at flower opening to allow plant reproduction. Male fertility results from sequential developmental events that involve an early phase of stamen formation and morphogenesis and a late phase that consists of pollen grain maturation, stamen filament elongation and anther dehiscence. In autogamous plants, such as Arabidopsis thaliana, stamen growth should be coordinated to pistil development to allow self-pollination. Proteins of the PIN-FORMED (PIN) family are the main group of efflux carriers with a polar cellular distribution (Gälweiler et al, 1998; Friml et al, 2003; Paponov et al, 2005; Friml, 2010). At least five members have been reported to mediate cellular transport of auxin (or auxin derivatives) coordinately with PIN proteins (Blakeslee et al, 2005; Titapiwatanakun et al, 2008; Zažímalová et al, 2010; Peer et al, 2011)

Auxin transport in stamen development

AUXIN TRANSPORT AND THE EARLY PHASE OF STAMEN DEVELOPMENT

Auxin response Transcription factors

Asynchronous elongation of stamen filaments and styles

Findings

CONCLUSIONS