SUPPRESSOR OF FRIGIDA (SUF4) Supports Gamete Fusion via Regulating Arabidopsis EC1 Gene Expression

Abstract

The EGG CELL1 (EC1) gene family of Arabidopsis (Arabidopsis thaliana) comprises five members that are specifically expressed in the egg cell and redundantly control gamete fusion during double fertilization. We investigated the activity of all five EC1 promoters in promoter-deletion studies and identified SUF4 (SUPPRESSOR OF FRIGIDA4), a CH transcription factor, as a direct regulator of the EC1 gene expression. In particular, we demonstrated that SUF4 binds to all five Arabidopsis EC1 promoters, thus regulating their expression. The down-regulation of SUF4 in homozygous suf4-1 ovules results in reduced EC1 expression and delayed sperm fusion, which can be rescued by expressing SUF4-β-glucuronidase under the control of the SUF4 promoter. To identify more gene products able to regulate EC1 expression together with SUF4, we performed coexpression studies that led to the identification of MOM1 (MORPHEUS' MOLECULE1), a component of a silencing mechanism that is independent of DNA methylation marks. In mom1-3 ovules, both SUF4 and EC1 genes are down-regulated, and EC1 genes show higher levels of histone 3 lysine-9 acetylation, suggesting that MOM1 contributes to the regulation of SUF4 and EC1 gene expression.

Time-Course Transcriptome Analysis of Arabidopsis Siliques Discloses Genes Essential for Fruit Development and Maturation

“…The GUS assay was carried out as reported by Resentini et al (2017). Marker lines were kindly provided by Takashi Araki (pFT; Takada and Goto, 2003), Jan U. Lohmann (pARR15; Zhao et al, 2010), and Ian Graham (pABI5::GUS; Penfield et al, 2006).…”

Elucidating small RNA pathways in Arabidopsis thaliana egg cells

“…S3). We furthermore added four EC1 genes with known egg cell-specific expression to the analysis (Sprunck et al, 2012; Resentini et al, 2017), since only one EC1 family member ( EC1.5 ) was included. When we compared the gene expression profiles in the replicates generated from CIM and RKD2-induced calli, most TPMs were significantly higher in the RKD2-induced callus and therefore in line with the microarray-based expression data of Kőszegi et al (2011).…”

HEBE, a novel positive regulator of senescence in Solanum lycopersicum

“…The Solyc12g03648/HEB gene (981 bp) cloned into pBlueScript II SK(+) vector was purchased from Biomatik Corporation (Cambridge, Canada), excised with EcoRI and XhoI and ligated into pGADT7 (Clontech) EcoRI/XhoI digested. The prey plasmid (HEB-pGADT7) was introduced into Saccharomyces cerevisiae AH109 strain (Clontech) and transformants mated with Y187 strain containing the bait plasmid as described by Resentini et al 104 . Diploids were selected on medium lacking Trp and Leu.…”