Embryogenesis: Pattern Formation from a Single Cell

Abstract

During embryogenesis a single cell gives rise to a functional multicellular organism. In higher plants, as in many other multicellular systems, essential architectural features, such as body axes and major tissue layers are established early in embryogenesis and serve as a positional framework for subsequent pattern elaboration. In Arabidopsis, the apicalbasal axis and the radial pattern of tissues wrapped around it are already recognizable in young embryos of only about a hundred cells in size. This early axial pattern seems to provide a coordinate system for the embryonic initiation of shoot and root. Findings from genetic studies in Arabidopsis are revealing molecular mechanisms underlying the initial establishment of the axial core pattern and its subsequent elaboration into functional shoots and roots. The genetic programs operating in the early embryo organize functional cell patterns rapidly and reproducibly from minimal cell numbers. Understanding their molecular details could therefore greatly expand our ability to generate plant body patterns de novo, with important implications for plant breeding and biotechnology.

Tryptophan-independent auxin biosynthesis contributes to early embryogenesis in Arabidopsis

“…In Arabidopsis, the early axis pattern is predominantly set up during early embryogenesis and provides the positional reference to postembryonic development (18). INS shows spatiotemporal expression patterns during embryogenesis and contributes to the establishment of an auxin gradient during embryogenesis.…”

“…In the wild type, a zygote divides asymmetrically, generating a smaller apical cell and a larger basal cell. The apical cell undergoes two rounds of longitudinal, one round of horizontal, and one round of periclinal divisions, giving rise to a 16-cell embryo proper, whereas the basal cell divides transversely to produce the suspensor (18). The uppermost suspensor cell is specialized to the hypophysis (HY), which subsequently produces an upper lens-shaped cell (LSC) that will form the quiescent center (QC) and a lower daughter cell that will form the columella stem cells (CSC) (Fig.…”

“…During embryogenesis, a singlecelled zygote develops into a functional multicellular organism with cells adopting specific fates according to their relative positions. In higher plants, essential architecture features, such as body axes and major tissue layers, are established in embryogenesis, and auxin plays a vital role in apical-basal patterning and embryo axis formation (18,19). Local auxin biosynthesis, polar auxin transport facilitated by PIN-FORMED1/3/4/7 (PIN1/3/4/7), and auxin response coordinately regulate apical-basal pattern formation during embryogenesis (7,(20)(21)(22).…”

Genome-wide analysis of spatio-temporal gene expression patterns during early embryogenesis in rice

“…These analyses revealed that the spatial distribution of gene expression was significantly different between the TF families. TF families in Type I, such as HB and YABBY, include putative homologs of well-known developmental regulators expressed in specific parts of early embryos in Arabidopsis (Capron et al, 2009). By contrast, Type I TF families also contained genes for which functions in embryogenesis remain unknown, even in Arabidopsis.…”

DNA damage and base excision repair : an important role during zebrafish embryogenesis

“…This is a highly complex, tightly regulated, and coordinated process (Capron et al 2009) The occurrence of DNA damage during embryonic development has received little attention in the past.…”