Maj. Toonen et al., DESCRIPTION OF SOMATIC-EMBRYO-FORMING SINGLE CELLS IN CARROT SUSPENSION-CULTURES EMPLOYING VIDEO CELL TRACKING, Planta, 194(4), 1994, pp. 565-572
A cell-tracking system was established to determine the capability of
individual single suspension cells of carrot (Daucus carota L.) to dev
elop into somatic embryos. When immobilised in phytagel, 127 out of 30
318 single suspension cells smaller than 22 mu m in diameter develope
d into a somatic embryo. Single cells present at the start of the expe
riment were classified on the basis of their morphology into five grou
ps: small spherical vacuolated cells; small spherical cytoplasm-rich c
ells; oval vacuolated cells;elongated vacuolated cells and cells that
could not be classified into either one of these groups. Single cells
of all morphologically distinguishable single cell types developed int
o somatic embryos with a frequency that varied between 19 and 100 soma
tic embryos per 10 000 cells. This suggests that the capability of ind
ividual single cells to form somatic embryos is not restricted to a pa
rticular cell type distinguishable on the basis of its morphology. Thr
ee major pathways were observed during development. Oval and elongated
cells developed into somatic embryos via an asymmetrical cell cluster
. Spherical cells developed via a symmetrical cell cluster into somati
c embryos. Before formation of a somatic embryo, cells of a more varia
ble initial morphology first developed aberrantly shaped cell clusters
. This suggests that the developmental pathway leading to a somatic em
bryo can be predicted by the initial single-cell morphology.