A Possible Explanation of Symptom Formation in Tobacco with Frenching and Mineral Deficiencies

Abstract

Maryland Medium Broadleaf tobacco seedlings grown in aseptic culture, and in water culture with excess amino acids in the medium show chloroses and abnormalities in growth of great variety, but specific for each amino acid. A close approximation of the extreme symptoms of frenching is obtained using natural L(+)-isoleucine, the unnatural isomer being relatively ineffective. Large-scale analytical studies of field plants afford some confirmation of the hypothesis that the immediate cause of symptoms of mineral deficiency may be the excessive accumulation of free amino acids in the plant, and that these minerals are implicated in protein synthesis.