Importance of transcription factors in the regulation of plant secondary metabolism and their relevance to the control of terpenoid accumulation

Transcription factors are known to play a key role in regulating flux through pathways of secondary metabolism, by controlling the levels of pathway gene expression. This regulatory mechanism seems to be important for the terpenoid pathway, as accumulation of many stress-induced and stored terpenoids often follows coordinated induction of pathway genes. Whereas the body of knowledge on regulators of the flavonoid pathway is already quite large, transcription factors controlling plant terpenoid accumulation are just starting to be identified. In addition to their role in metabolic control, transcription factors are also essential in the differentiation of cells that produce and accumulate terpenoids. In particular, they appear to play an important role in the initiation and differentiation of glandular trichomes, which are a major site of terpenoid accumulation in plants. We are presenting here some of the recent findings on the role played by these important regulatory proteins in secondary metabolism and in terpenoid biosynthesis, as well as the picture that is starting to emerge of their implication in differentiation and metabolic processes leading to the accumulation of terpenoids in plants.