Résumé
In
Catharanthus roseus, monomeric terpenoid indole alkaloids (TIAs) are biosynthesized in specific tissues, particularly in roots, but failed to be produced by
in vitro undifferentiated suspension cells. In this paper, we describe the impact of the root-specific MADS-box transcription factor Agamous-like 12 (
Agl12) from
Arabidopsis thaliana on the differentiation of suspension cells from
C. roseus. The expression of
Agl12 is sufficient to promote an organization of suspension cells into globular parenchyma-like aggregates but is insufficient by itself to induce complete morphological root differentiation.
Agl12 expression selectively increases the expression of genes encoding enzymes involved in the early biosynthesis steps of the terpenic precursor of alkaloids. The transgenic cell lines expressing
Agl12 produced significant amounts of ajmalicine, an antihypertensive TIA that normally accumulates in
C. roseus roots. The present paper indicates that transcription factors involved in tissue or organ differentiation may constitute new metabolic engineering tools that could help to design
in vitro cultured cells able to produce specific valuable secondary metabolites.