N. Michauxferriere et J. Schwendiman, INITIATION SEQUENCE PATTERNS FOR SOMATIC EMBRYO ORIGINATING CELLS, Acta botanica gallica, 140(6), 1993, pp. 603-613
A histological survey of the embryogenic process in Hevea brasiliensis
and Coffea sp. has shown that somatic embryos may find their origin a
ccording to two cell categories : embryogenic or embryonic cells. Thos
e were initiated at a special time during the callus phase from merist
ematic or parenchymatous cells. In friable calli of coffee capable to
give numerous somatic embryos (high frequency calli), embryogenic cell
s resulted from the dedifferentiation and then internal compartmentati
on divisions of large highly vacuolated cells containing numerous star
ch and protein reserves. When somatic embryos were of a unicellular or
igin, they issued from the development of an isolated embryogenic cell
. When they were of a multicellular origin, they formed either from as
sociated embryogenic cells or from the evolution of a cluster of embry
onic cells.