Electrophoretic Patterns of Xanthium Leaf Extracts as Affected by Physiological Age of Leaf, Photoperiod, & Age of Plant

It is well known that vegetative plants of Xanthium are induced to flower when a photoperiodically induced scion is grafted onto them. However, attempts to replace this donor scion with an active extract failed (2). These negative results gave rise to an hypothesis that labile macromolecules might be involved in floral induction (2). Since it was not possible to produce an active extract, attempts were made to identify the possible nature of the inducing substance by using various unnatural analoges of natural metabolites (5, 10). In the present investigation I seek a different approach and am concerned with those macromolecular entities in the leaf that are affected by photoperiod and by the physiological age of the leaf. This approach is supported by the knowledge that in Xanthium the physiological age of leaf plays a significant role in floral induction (6,12). It had been found previously, in plants other than Xanthium, that quantitative differences occur in some main protein components isolated from leaves at different stages of development (1, 3,13) or from leaves exposed to different light intensities (7,13). Free-boundary electrophoresis was chosen to resolve leaf extracts into main groupings of macromolecular components. The electrophoretic patterns obtained may serve as a first clue for further investigation along these lines.