BASAL PLATE TISSUE IN NARCISSUS BULBS AND IN SHOOT CLUMP CULTURES - ITS STRUCTURE AND ROLE IN ORGANOGENIC POTENTIAL OF SINGLE LEAF CULTURES

Light microscopy demonstrated that the apparently amorphous, achlorophyllous tissue at the base of in vitro shoot clump cultures of Narcissus was comparable in structure to the basal plate of Narcissus bulbs. Both had very complex vascularisation and small, densely packed parenchymatous cells. In shoot clump cultures, primordia were produced by meristematic zones at the surface of this achlorophyllous tissue, very close to the base of leaves. Single leaf units excised from the in vitro shoot clump cultures with a wedge of basal achlorophyllous tissue were highly organogenic when used as secondary explants for in vitro culture of Narcissus. No organogenesis occurred in the absence of the leaf base and achlorophyllous (basal plate) tissue and little organogenesis occurred unless the leaf base and basal plate tissue were immersed in the culture medium (i.e. explants inoculated into liquid medium or upright in agar-solidified medium). After two 5-week culture passages in liquid medium, more than five leaves were produced per leaf base inoculated. Thus rapid micropropagation of Narcissus can be achieved using only the base of single leaf units excised from shoot clump cultures. © 1993 Annals of Botany Company.