Fy. Bouget et al., POSITION-DEPENDENT CONTROL OF CELL FATE IN THE FUCUS EMBRYO - ROLE OFINTERCELLULAR COMMUNICATION, Development, 125(11), 1998, pp. 1999-2008
The early embryo of the brown alga Fucus comprises two cell types, i.e
. rhizoid and thallus which are morphogically and cytologically distin
guishable. Previous work has pointed to the cell wall as a source of p
osition-dependent information required for polarisation and fate deter
mination in the zygote and 2-celled embryo, In this study we have anal
ysed the mechanism(s) of cell fate control and pattern formation at la
ter embryonic stages using a combination of laser microsurgery and mic
roinjection. The results indicate that the cell wall is required for m
aintenance of pre-existing polarity in isolated intact cells, However,
all cell types ultimately have the capacity to re-differentiate or re
generate rhizoid cells in response to ablation of neighbouring cells.
This regeneration is regulated in a position-dependent manner and is s
trongly influenced by intercellular communication, probably involving
transport or diffusion of inhibitory signals which appear to be essent
ial for regulation of cell fate decisions. This type of cell-to-cell c
ommunication does not involve symplastic transport or direct cell-cell
contact inhibition. Apoplastic diffusible gradients appear to be invo
lved in pattern formation in the multicellular embryo.