Arabidopsis Female Gametophyte Gene Expression Map Reveals Similarities between Plant and Animal Gametes

Abstract

The development of multicellular organisms is controlled by differential gene expression whereby cells adopt distinct fates. A spatially resolved view of gene expression allows the elucidation of transcriptional networks that are linked to cellular identity and function. The haploid female gametophyte of flowering plants is a highly reduced organism: at maturity, it often consists of as few as three cell types derived from a common precursor [1, 2]. However, because of its inaccessibility and small size, we know little about the molecular basis of cell specification and differentiation in the female gametophyte. Here we report expression profiles of all cell types in the mature Arabidopsis female gametophyte. Differentially expressed posttranscriptional regulatory modules and metabolic pathways characterize the distinct cell types. Several transcription factor families are overrepresented in the female gametophyte in comparison to other plant tissues, e.g., type I MADS domain, RWP-RK, and reproductive meristem transcription factors. PAZ/Piwi-domain encoding genes are upregulated in the egg, indicating a role of epigenetic regulation through small RNA pathways-a feature paralleled in the germline of animals [3]. A comparison of human and Arabidopsis egg cells for enrichment of functional groups identified several similarities that may represent a consequence of coevolution or ancestral gametic features.

DCL2 is highly expressed in the egg cell in both rice and Arabidopsis

“…A recent study determined the cell type-specific expression profiles in the female gametophyte of Arabidopsis by using laser-assisted microdissection (LAM). 18 Unfortunately, however, no enrichment of the AtDCL2 transcript was detected in the egg cells in this study. This may be due to crosscontamination effects by neighboring cells on the expression profiles of the egg cells, a problem which is difficult to avoid in LAM experiments.…”

Seed Production Affects Maternal Growth and Senescence in Arabidopsis

“…The slides were then dried overnight at 42°C on a heating table and laser dissected immediately. LAM was performed on a Molecular Machines and Industries CellCut Plus after dewaxing the tissue sections for 2 3 10 min in xylol as described by Wuest et al (2010).…”

Identification of genes preferentially expressed in wheat egg cells and zygotes

“…Recent genomic approaches allowed a deep insight into the egg cell transcriptome of the 5 model species Arabidopsis and rice (Wuest et al 2010;Ohnishi et al 2011) and these data 6 indicate considerable species-specific differences. 7…”

“…Modern, high-throughput 11 techniques allowed studying of the transcriptome of these specialized cells in model species 12 (for review; Schmidt et al 2012b). Functional characterization of the transcripts revealed 13 differences highlighting specific posttranscriptional regulatory modules and metabolic 14 pathways characteristic for each female gametophytic cell type (Wuest et al 2010). However, 15…”

“…Wuest and coworkers (Wuest et al 2010) could 21 identify 431 genes which are likely to be specifically expressed in the mature female 22 gametophyte of Arabidopsis thaliana of which 163 was specifically expressed in the egg. In 23 animals, maternally deposited mRNAs in the egg cell control early embryonic development 24 mRNA isolation and cDNA library preparation 22 mRNA isolation was carried out according to the protocol provided by the manufacturer 23 ("Dynabeads mRNA Direct" RNA isolation kit; Invitrogen) after adding 90 l-s of 24…”