A study of kinetin in plants

Abstract

Since the discovery of kinetin in 1954, the translocation pattern of this plant growth regulator had remained obscure. On the basis of general observation, it has been assumed that kinetin is largely immobile in plants. Reponses such as senescence retardation, cell enlargement and certain mobilizing effects of kinetin have all occurred in the area where kinetin have all occurred in the area where kinetin was applied. No extractions have been made from plant parts distant to the applied area in order to obtain translocated kinetin. As a result, kinetin's movement in plants has remained unknown. The object of this study, one of the first to employ radioactive kinetin, was to investigate kinetin translocation and other response elicited by this growth regulator. The major contributions of this study are as follows: 1. The development of a method for maintaining detached leaves for extended periods of time. 2. The development of a method for assaying radioactivity in aqueously prepared agar samples with a liquid scintillation spectrometer. 3. The development of a bioassay for the qualitative determination of kinetin-like substances. This test was based on the senescence retarding effect of kinetin as visualized by retardation of chlorophyll breakdown in primary bean leaf disks. Treated areas stayed green and could be correlated to exposed areas on radioautographs when kinetin-8-¹⁴C was used. 4. The development of a tobacco-leaf disk bioassay in which the influence of light on kinetin in plants could be measured. 5. The development of a spectrophotometric chlorophyll assay suitable for evaluating differences in senescence as gauged by chlorophyll content. ...