Hormone-like effects of vascular tissue on the development of stem explants of kale

Abstract

Summary Explants of stem pith of kale (Brassia oleracea L. var. medullosa cv. Krasa ), cultured on simple sucrose medium, accumulate starch, protein and total dry mass. The callus is formed on a complex, growth promoting medium. If the explants contain, in addition to the pith parenchyma, the vascular tissue including the cambium, the development of pith tissue on both types of media is stimulated: The amounts of starch, protein and dry mass (on simple medium) and of fresh mass (on complex medium) increases several times when compared with control explants without the vascular tissue. If cytokinin and auxin are added to the sucrose medium, the accumulation of starch, protein and dry mass is stimulated in both the control and the vascular tissue containing explants. The effect of vascular tissue on explant growth manifests itself, analogically, at different concentrations of both phytohormones in a complex medium. The stimulatory action of vascular tissue is supposed to be mediated by a hormone-like factor which is produced even under conditions that are unfavorable for cell proliferation.