Free Amino Acid Levels in Nicotiana glauca, N. Langsdorffii and Their Interspecific Hybrid Following Gamma Irradiation.

Abstract

Two tobacco species and their interspecific hybrid, at approximately the same physiological age, were subjected for 2 months to various dosages of chronic gamma radiation between 25 and 400 r/20-hour day. Leaf abnormalities were evident at all dosages in N. glauca plants, above 50 r in the hybrid, and above 150 r in N. langsdorffii. In all 3 cases there was a concomitant increase in the free amino acid content of the irradiated leaves as determined by paper chromatography. In addition, the hybrid formed large masses of tumor tissue at dosages between 250 and 400 r. As tumors formed, acid levels decreased (except glycine) in the leaves and increased in the tumor, especially glutamic acid, glutamine and asparagine. Old tumor tissue showed a drop in both asparagine and glutamine. Comparable leaf abnormalities and changes in free amino acid levels and ratios in tobacco are found following maleic hydrazide treatment or trenching disease.