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.     

Floral determination in adventitious shoot meristems regenerated from leaves of day-neutral tobacco

The developmental patterns of adventitious shoots regenerated from cultured leaf tissue and the petioles of leaf cuttings of flowering day-neutral tobacco plants were assessed. Leaf tissue, removed from leaves within the inflorescence, was cultured on hormone-free medium and produced a limited number of adventitious shoots. These shoots produced the same number of nodes that would be produced by a seedling meristem. Most leaf-cutting derived shoots produced the same number of nodes that would be produced by a seedling meristem prior to flowering, while a few shoots produced very few nodes and flowered. Some plants appeared to be intermediate in response. Results indicated that the developmental state or the developmental response of all petiole cells is not the same. The influence of position and the potential reversibility in developmental fate of cell populations within leaves is discussed in the context of existing theory.