Résumé
Theobroma cacao
L., an economically important crop for developing countries, can be experimentally propagated by somatic embryogenesis. Because of their potential roles in embryogenesis, a gene candidate strategy was initiated to find gene homologues of the members of the leafy cotyledon family of transcription factors. A homologue of the
leafy cotyledon1-like
gene, that encodes the HAP 3 subunit of the CCAAT box-binding factor, was found in the cocoa genome (
TcL1L
). The translated peptide shared a high amino acid sequence identity with the homologous genes of
Arabidopsis thaliana
,
Phaseolus coccineus
and
Helianthus annuus
.
TcL1L
transcripts mainly accumulated in young and immature zygotic embryos, and, to a lesser extent, in young and immature somatic embryos. In situ hybridization specified the localization of the transcripts as being mainly in embryonic cells of young embryos, the meristematic cells of the shoot and root apex of immature embryos, and in the protoderm and epidermis of young and immature embryos, either zygotic or somatic. Non-embryogenic explants did not show
TcL1L
expression. Ectopic expression of the
TcL1L
gene could partially rescue the
Arabidopsis
lec1
mutant phenotype, suggesting a similarity of function in zygotic embryogenesis.