Epigenetic marks in the Hyacinthus orientalis L. mature pollen grain and during in vitro pollen tube growth.

Marlena Kozłowska,Marta Brzostek,Katarzyna Niedojadło,Elżbieta Bednarska-Kozakiewicz

doi:10.1007/s00497-016-0289-3

Marlena Kozłowska, Marta Brzostek + Show 2 more

Open Access

https://doi.org/10.1007/s00497-016-0289-3

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Journal: Sexual Plant Reproduction	Publication Date: Jul 15, 2016
Citations: 3	License type: CC BY 4.0

Affiliation: Nicolaus Copernicus University

Abstract

During the sexual reproduction of flowering plants, epigenetic control of gene expression and genome integrity by DNA methylation and histone modifications plays an important role in male gametogenesis. In this study, we compared the chromatin modification patterns of the generative, sperm cells and vegetative nuclei during Hyacinthus orientalis male gametophyte development. Changes in the spatial and temporal distribution of 5-methylcytosine, acetylated histone H4 and histone deacetylase indicated potential differences in the specific epigenetic state of all analysed cells, in both the mature cellular pollen grains and the in vitro growing pollen tubes. Interestingly, we observed unique localization of chromatin modifications in the area of the generative and the vegetative nuclei located near each other in the male germ unit, indicating the precise mechanisms of gene expression regulation in this region. We discuss the differences in the patterns of the epigenetic marks along with our previous reports of nuclear metabolism and changes in chromatin organization and activity in hyacinth male gametophyte cells. We also propose that this epigenetic status of the analysed nuclei is related to the different acquired fates and biological functions of these cells.Electronic supplementary materialThe online version of this article (doi:10.1007/s00497-016-0289-3) contains supplementary material, which is available to authorized users.

Highlights

In flowering plants, pollen grains germinate to form pollen tubes that transport the sperm cells to the egg cell in the embryo sac during sexual plant reproduction
We discuss the differences in the localization of these epigenetic marks along with our previous reports (Zienkiewicz et al 2006, 2008a, b, c, 2011) in which we examined nuclear metabolism and changes in the organization of the molecules involved in the key steps of gene expression in the vegetative cell (VC), generative cell (GC) and sperm cells (SCs) formed during pollen tube growth
Stage V is the late phase of pollen tube growth, between 6 and 12 h of cultivation, when the pollen tubes form callose plugs and the cytoplasm is localized near the growing tip

Summary

Introduction

Pollen grains germinate to form pollen tubes that transport the sperm cells to the egg cell in the embryo sac during sexual plant reproduction. Depending on the plant species, the generative cell divides into two sperm cells (SCs), either during pollen maturation in the anther (tricellular pollen grain) or after pollination inside the pollen tube (bicellular pollen grain) (for review Twell 2011; Russell and Jones 2015). The generative cell, or one sperm cell, associates with the vegetative nucleus, establishing the ‘male germ unit’ (Russell and Cass 1981; Dumas et al 1985; McCue et al 2011). Plant Reprod (2016) 29:251–263 physical connection allows it to travel as a unit through the growing pollen tube to the female gametophyte where fertilization of the egg and the central cell generates the embryo and the endosperm, respectively (McCue et al 2011; Ge et al 2011). Molecular data suggest that MGU linkage is essential for communication between the VC and SCs (Tian et al 1998; Slotkin et al 2009; Hamamura et al 2011; Grant-Downton et al 2013; Jiang et al 2015)

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