ONTOGENY, DIFFERENTIATION AND PRECOCIOUS GERMINATION IN ANTHER-DERIVED SOMATIC EMBRYOS OF GRAPEVINE (VITIS-VINIFERA L) - PROEMBRYOGENESIS

Histological steps of callogenesis and proembryogenesis in anther cult ures of Vitis vinifera L. 'Grenache noir' are described. Embryogenic c alli were obtained on Nitsch and Nitsch medium supplemented with 1 mg l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.25 mg l(-1) benzyla minopurine (BAP). Calli were initiated from anther connective cells on ly and no division of microspores occurred. The embryos were hence of somatic origin. Proembryos developed either directly (i.e. without int ervening callus) from the endothecium, or indirectly from the connecti ve-derived callus. In both cases, proembryos originated from single ce lls. They developed from starchy differentiated cells of a predetermin ed type. The polarity of the somatic proembryo was established from th e first divisions and it was marked by precocious development of an ea sily recognizable suspensor. Other analogies with the development of t he zygote are also emphasised. (C) 1996 Annals of Botany Company