Regulators of cell division in plant tissues

Abstract

Kinins have been detected in extracts of fruitlets of a number of species. Plum fruitlet extracts also contained growth inhibitors which were seperated fron the kinins. These inhibitors and kinins did not appear to be artifactof the extraction procedure. The kinin activity of plum extract was due to two or more factors which interacted synergistically with auxins to promote cell division. Kinin activity of apple fruitlet extracts was greatest during the period of intense cell division characteristic of the development of the apple fruit and declined just before the cessation of thid period. With plum fruitlets the highest activity occurred at the onset of active cell division. Kinins may therefore play some role in the regulation of cell division in both these fruitlets. Extract from plum fruitlet showed greatest inhibitory activity during the cell division period, the activity declining at the time of cessation of division. These inhibitors are therefore unlikeky to be solely responsible for the observed cessation of division.