Department of Botany, University of Delhi, Delhi-110 007
*Present address: S.S.N, College, University of Delhi, Alipur, Delhi.
Standardization through extensive segmentation of detached leaves bearing variable numbers of epiphyllous buds has been done to characterize it as a model developmental system. The study revealed that a pair of roots always emerged prior to shoot emergence from each bud. The buds from the middle region of the leaves were more responsive (earlier organ initiation) and more uniformly so than those from the distal regions. The existence of such a pattern of differentiation even in leaf cuttings, squares and discs points to the operation of some endogenous physiological gradients along linear leaf axis, not disturbed by system miniaturization. Enlargement of photosynthetic tissue at the disposal of a single bud did not accelerate organogenesis.
The designed experimental system responded well to exogenous application of chloramphenicol and cycloheximide—inhibitors of protein synthesis, by exhibiting an overall inhibition of bud differentiation, the effect increasing with concentration. Chloramphenicol was more inhibitory than cyclobeximide, completely blocking organogenesis at300mg/l dose level whereas cyclobeximide could not do so even at a concentration of 500 mg/1. Similarly, only chloramphenicol could reduce the percentage of discs showing differentiation.
