Phenotypic and ploidy status of Paulownia tomentosa trees regenerated from cultured hypocotyls

Shoots of Paulownia tomentosa Steud., the Empress tree, were regenerated from cultured hypocotyl segments. The phenotypic and ploidy status of a population of regenerated trees was investigated and compared with a control population of trees grown from seed. Five of the six measured phenotypic characteristics were not significantly different between both populations of plants. Twenty of twenty-one shoots had the normal diploid chromosome number and one was apparently mixoploid. Five phenotypic variants were recovered, including a variegated variant that appearsr to be a plastid chimera undergoing a segregation of normal and mutant plastids. The variegated variant was the only stable variant. All other variants displayed typical morphology in their second year of growth. Precocious flowering of five regenerated plantlets occurred in their first year of growth. These plants were derived from different hypocotyls and did not flower the subsequent year.