Reference "Position dependent expression of GL2-type homeobox gene, Roc1: significance for protoderm differentiation and radial pattern formation in early rice embryogenesis"

Reference ID

6685

Title

Position dependent expression of GL2-type homeobox gene, Roc1: significance for protoderm differentiation and radial pattern formation in early rice embryogenesis

Source

The Plant journal : for cell and molecular biology, 2002, vol. 29, pp. 497-507

Authors (6)

Ito-M	Sentoku-N
Nishimura-A	Hong-S-K
Sato-Y	Matsuoka-M

Abstract

In early plant embryogenesis, the determination of cell fate in the protodermal
cell layer is considered to be the earliest event in radial pattern formation.
To elucidate the mechanisms of epidermal cell fate determination and radial
pattern formation in early rice embryogenesis, we have isolated a GL2-type
homeobox gene Roc1 (Rice outermost cell-specific gene1), which is specifically
expressed in the protoderm (epidermis). In early rice embryogenesis, cell
division occurs randomly and the morphologically distinct layer structure of the
protoderm cannot be observed until the embryo reaches more than 100 microm in
length. Nonetheless, in situ hybridization analyses revealed that specific
expression of Roc1 in the outermost cells is established shortly after
fertilization, much earlier than protoderm differentiation. In the regeneration
process from callus, the Roc1 gene is also expressed in the outermost cells of
callus in advance of tissue and organ differentiation, and occurs independently
of whether the cells will differentiate into epidermis in the future or not.
Furthermore, this cell-specific Roc1 expression could be induced flexibly in the
newly produced outermost cells when we cut the callus. These findings suggest
that the expression of Roc1 in the outermost cells may be dependent on the
positional information of cells in the embryo or callus prior to the cell fate
determination of the protoderm (epidermis). Furthermore, the Roc1 expression is
downregulated in the inner cells of ligule, which have previously been
determined as protodermal cells, also suggesting that the Roc1 expression is
position dependent and that this position dependent Roc1 expression is important
also in post-embryonic protoderm (epidermis) differentiation.