Reproduction and the pheromonal regulation of sex type in fern gametophytes.

Nadia M Atallah,Jo Ann Banks

doi:10.3389/fpls.2015.00100

Abstract

The fern life cycle includes a haploid gametophyte that is independent of the sporophyte and functions to produce the gametes. In homosporous ferns, the sex of the gametophyte is not fixed but can vary depending on its social environment. In many species, the sexual phenotype of the gametophyte is determined by the pheromone antheridiogen. Antheridiogen induces male development and is secreted by hermaphrodites once they become insensitive to its male-inducing effect. Recent genetic and biochemical studies of the antheridiogen response and sex-determination pathway in ferns, which are highlighted here, reveal many similarities and interesting differences to GA signaling and biosynthetic pathways in angiosperms.

Highlights

In this review we highlight old and recent studies that have revealed the fascinating cross-talk that occurs between neighboring gametophytes in determining what their sexual phenotype will be
Induced apogamous sporophytes of C. richardii have features typical of the sporophyte, including stomata, vascular tissue and scale-like ramenta; they are abnormal compared to sexually-derived diploid sporophytes, which could be a consequence of being haploid
Understanding apogamy, coupled with studies of apospory in C. richardii, where diploid gametophytes develop from cells of sporophyte leaves without meiosis (DeYoung et al, 1997), should provide useful insights into genes and molecular mechanisms that regulate the alternation of gametophyte and sporophyte generations in ferns in the absence of meiosis and fertilization

Summary

Reproduction and the pheromonal regulation of sex type in fern gametophytes

The fern life cycle includes a haploid gametophyte that is independent of the sporophyte and functions to produce the gametes. The sex of the gametophyte is not fixed but can vary depending on its social environment. The sexual phenotype of the gametophyte is determined by the pheromone antheridiogen. Antheridiogen induces male development and is secreted by hermaphrodites once they become insensitive to its male-inducing effect. Recent genetic and biochemical studies of the antheridiogen response and sex-determination pathway in ferns, which are highlighted here, reveal many similarities and interesting differences to GA signaling and biosynthetic pathways in angiosperms

INTRODUCTION

Sex determination in ferns