Morphological changes in tissue culture of Petunia hybrida in response to coumarin allelochemical

Coumarin induces metabolic and morphofunctional changes in Petunia hybrida leaf explants. The tissues grown in the presence of coumarin show long root s with few root hairs. However, the leaf explants grown with indoleacetic a cid show short roots with abundant root hairs. The presence of both indolea cetic acid and coumarin induces long roots with numerous root hairs. The pr esence of both indoleacetic acid and coumarin induces long roots with numer ous root hairs. Peroxidase and IAA-oxidase activity were analysed. Results obtained indicate that coumarin may control the endogenous auxin level inte rfering with peroxidase systems. The IAA-oxidase activity remains low in th e culture tissues treated with coumarin. Peroxidase and esterase isoforms i n leaf explant extracts, treated with coumarin, exhibit a pattern similar t o those induced by indoleacetic acid. Acting as a plant growth regulator an d affecting auxin metabolism, coumarin interferes with differentiation proc esses.