Cell division factors (cytokinins) from irradiated plant tissue

Abstract

REPORTS on the effects of ionising radiation on plant cells in callus culture are quite limited. Work on a few species^1–3 has shown that low doses of γ radiation, starting at 0.5 krad, stimulate callus growth and differentiation. Larger doses ranging from a few krad to about 20 krad inhibit growth and differentiation, respectively. High doses (16 krad and above) have been shown to alter culture media components chemically and thereby affect cell growth⁴ and differentiation². We now report that gamma irradiation (1–2 krad) of Haworthia in callus culture results in the formation of cytokinins⁵—cell division factors—not detected in nonirradiated tissue.