Catabolic ring-cleavage of tyrosine in plant cell cultures

Ten species of plants from 8 families, grown as sterile cell cultures, were examined for their ability to degrade the aromatic ring of L-tyrosine and two of its metabolites, homogentisic acid and 3,4-dihydroxyphenylalanine (DOPA). All cultures showed low levels of tyrosine degradation (0.3-2.6% in 24 h) and high levels of homogentisic acid degradation (9.3-31.0% in 24 h). Cultures of Amaranthus caudatus L. resembled the other nine species in possessing a moderate capacity for DOPA degradation (0.3-11.1% in 24 h).