ABSTRACT
After fertilization in animals, maternal mRNAs and proteins regulate development until the onset of zygotic transcription. In plants, the extent of maternal regulation of early embryo development has been less clear: two hybrid combinations of rice zygotes have a strong maternal transcript bias, zygotes of a third rice hybrid produced by gamete fusion show a small percentage of maternally biased genes, while Arabidopsis Col/Cvi and Col/Ler hybrid embryos display symmetric and asymmetric parental genome activation, respectively. Here, we explore parent-of-origin transcriptome behavior in the Arabidopsis Col/Tsu hybrid, which was previously shown to display maternal effects for embryo defective mutants indistinguishable from those of the reference ecotype, Col. Analysis of Col/Tsu transcriptomes revealed a reciprocal maternal bias in thousands of genes in zygotes and octant stage embryos. Several lines of evidence suggest that this transient maternal bias is due to preferential transcription of maternal alleles in the zygote, rather than inheritance of transcripts from the egg. Our results extend previous observations that parent-of-origin contributions to early embryogenesis differ between hybrids of Arabidopsis, show that the maternal genome plays a predominant role in early embryos of Col/Tsu, and point to a maternal transcriptome bias in early embryos of the Arabidopsis reference ecotype Columbia.
Footnotes
Author contributions
Conceptualization: J.A.-F., D.X., R.D., C.S.G.; Data curation: J.A.-F., P.G.; Formal analysis: J.A.-F., C.A.-G., C.S.G.; Funding acquisition: R.D., C.S.G.; Investigation: J.A.-F., D.X., G.D.T.-D.L., R.D., C.S.G.; Methodology: J.A.-F., D.X., P.G., C.A.-G.; Project administration: R.D., C.S.G.; Supervision: R.D., C.S.G., C.A.-G.; Visualization: J.A.-F., G.D.T.-D.L.; Writing – original draft: J.A.-F., C.A.-G., C.S.G.; Writing – review & editing: J.A.-F., D.X., G.D.T.-D.L., P.G., C.A.-G., R.D., C.S.G.
Funding
This work was supported by grants from the National Research Council Canada Genomics and Health Initiative (NRC-GHI) and the Aquatic and Crop Resource Development - National Research Council Canada (ACRD-NRC) (to R.D.), and by the Mexican Consejo Nacional de Humanidades, Ciencias y Tecnologías (CONAHCyT) Ciencia Básica (237480 and A1-S-34956 to C.S.G.).
Data availability
The data for unfertilized ovules have been deposited at Gene Expression Omnibus (GEO) under accession numbers GSM3864989 and GSM3864990. Raw data for Col×Tsu and Tsu×Col transcriptomes have been deposited at GEO under accession number GSE132449.
