LETHAL SYNTHESIS IN CYNODON DACTYLON GROWING IN SOUTHERN AFRICA

Abstract

Badenhuizen, N. P. (U. Toronto, Ont., Can.), and E. N. Lawson. Lethal synthesis in Cynodon dactylon growing in southern Africa. Amer. Jour. Bot. 49 (2) : 158–167. Illus. 1962.—Both cultivated and wild forms of Cynodon dactylon are characterized in southern Africa by the random production of chlorotic shoots. Some properties of these shoots were typical of chlorotic shoots in general: increase in water and soluble nitrogen content, and inhibition of protein synthesis, chloroplast development and catalase activity. Others, such as sterility and enhanced respiratory activity, were more characteristic of plants treated with streptomycin or amitrol. Allantoin could be demonstrated in the chlorotic shoots and was found to produce chlorosis after being applied to Cynodon plants. Additional characteristics included decreased total and “active” iron content, accompanied by an increase in citric acid. So far, the weight of evidence, including the ultrastructure of the plastids, is not in favor of a mutation, a virus, a fungus, or iron deficiency as the ultimate cause of chlorosis in Cynodon. There appears to be a tendency towards the production of allantoin which may be triggered off more frequently under certain conditions of environment, until a concentration is reached when it irreversibly inhibits stages in the development of the chloroplasts.