Skoog and Miller (1955) identified and crystallised a cytokinesis-promoting active substance termed kinetin. From which of the following materials was it originally isolated?

Step-by-step solution

F. Skoog and his co-workers observed that from the internodal segments of tobacco stems, the callus proliferated only if, in addition to auxins, the nutrient medium was supplemented with one of the following: extracts of vascular tissues, yeast extract, coconut milk, or DNA. Later, Skoog and Miller (1955) identified and crystallised the cytokinesis-promoting active substance from autoclaved herring sperm DNA and termed it kinetin. Coleoptile tips of oat seedlings are associated with the discovery of auxins by F.W.