He served as Director of the Plant Biology Division at the Samuel Roberts Noble Foundation in Ardmore, Oklahoma from 1998 to 2013.

For over 30 years he has been a world leader in the field of plant specialized metabolism, using multidisciplinary approaches to decipher the biosynthetic and regulatory pathways leading to lignin and bioactive flavonoids, and driving the field of metabolic engineering for development of more nutritious forages and bioenergy crops with enhanced traits for biorefining.

[2] From January 1, 2023 he has been Editor-in-Chief of Philosophical Transactions of the Royal Society B[10] and he is also a member of the Editorial Board for PNAS.

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