Transcription Profile Analysis Reveals That Zygotic Division Results in Uneven Distribution of Specific Transcripts in Apical/Basal Cells of Tobacco

Ligang Ma,Libo Yang,Lianghuan Qu,Mengxiang Sun,Jing Zhao,Peng Zhao,Haiping Xin,Frederic Berger

doi:10.1371/journal.pone.0015971

Abstract

BackgroundAsymmetric zygotic division in higher plants results in the formation of an apical cell and a basal cell. These two embryonic cells possess distinct morphologies and cell developmental fates. It has been proposed that unevenly distributed cell fate determinants and/or distinct cell transcript profiles may be the underlying reason for their distinct fates. However, neither of these hypotheses has convincing support due to technical limitations.Methodology/Principal FindingsUsing laser-controlled microdissection, we isolated apical and basal cells and constructed cell type-specific cDNA libraries. Transcript profile analysis revealed difference in transcript composition. PCR and qPCR analysis confirmed that transcripts of selected embryogenesis-related genes were cell-type preferentially distributed. Some of the transcripts that existed in zygotes were found distinctly existed in apical or basal cells. The cell type specific de novo transcription was also found after zygotic cell division.Conclusions/SignificanceThus, we found that the transcript diversity occurs between apical and basal cells. Asymmetric zygotic division results in the uneven distribution of some embryogenesis related transcripts in the two-celled proembryos, suggesting that a differential distribution of some specific transcripts in the apical or basal cells may involve in guiding the two cell types to different developmental destinies.

Highlights

In some angiosperms, including Arabidopsis and tobacco, the first zygotic cell division is transverse and asymmetric, and results in a two-celled proembryo consisting of an apical cell and a basal cell, which differ in both their morphology and destiny [1,2,3]
We address two questions: 1) Do apical and basal cell possess distinct transcript profiles that may be responsible for their distinct cell fates? and 2) Can zygotic transcripts be portioned into the different daughter cells, which may involve in cell fate regulation
The resulting apical and basal cells differ in terms of their morphology and developmental fate

Summary

Introduction

In some angiosperms, including Arabidopsis and tobacco, the first zygotic cell division is transverse and asymmetric, and results in a two-celled proembryo consisting of an apical cell and a basal cell, which differ in both their morphology and destiny [1,2,3]. It has been a mystery for many years how apical and basal cells, which are descended from the same mother cell, show distinct divisional patterns and cell fates To explain their distinct cell fates, it has been proposed that asymmetric divisions generate daughter cells containing different developmental determinants [5] or that the different developmental pathways of the cells occur due to different positional cues [6]. In Phaseolus coccineus, the transcripts of two genes, G564 and G541, accumulate shortly after fertilization and are present within the two embryonic basal cells at the four-cell stage [5] It was recently [9] reported that the transcription factors WUSCHEL HOMEOBOX2 (WOX2) and WOX8 are expressed in the apical and basal cells of the Arabidopsis two-celled proembryo. Neither of these hypotheses has convincing support due to technical limitations

Methods

Results

Conclusion