Maternal to zygotic transition:A two-step process with two phases of ZGA occurs in zygote right after fertilization in Arabidopsis

The goal of the present study is to analyze the characteristics of maternal to zygotic transition (MZT) in Arabidopsis. The maternal-to-zygotic transition (MZT) is an essential developmental turning point during the alternation of generations in both plants and animals. In animals, early embryogenesis is maternally controlled and zygotic genome activation (ZGA) starts much later. However, in plants, the timing of MZT and parental contributions to the zygotic transcriptome remain unclear. To address above mentioned questions, we selected Arabidopsis as model plant for the analysis. Regarding to the characteristics of MZT, egg cells, embryos including spherical zygote, elongated zygote, 1-cell embryo and 32-cell embryo were isolated and collected for RNA sequencing. Hybrid zygotes at two representative stages from the reciprocal crosses between polymorphic Arabidopsis Columbia (Col) and Landsberg erecta (Ler) accessions were also sequenced for investigating the parental contributions. We demonstrate that plant MZT occurs during the zygote stage and is a two-step process, first involving rapid maternal transcript degradation and, second, large-scale de novo transcription. Parental contributions to the zygotic transcriptome are stage dependent over the course of zygote development; the spherical zygote is characterized by a maternally dominated transcriptome, whereas the elongated zygote genome shows equal parental contributions. Overall design: Regarding to the characteristics of MZT, egg cells and embryos including spherical zygote, elongated zygote, 1-cell embryo and 32-cell embryo were isolated and collected for RNA sequencing (RNA-seq). Hybrid zygotes at two representative stages from the reciprocal crosses between polymorphic Arabidopsis Columbia (Col) and Landsberg erecta (Ler) accessions were also sequenced to investigate the parental contributions.

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Zhao P, Zhou X, Shen K, Liu Z, Cheng T, Liu D, Cheng Y, Peng X, Sun MX