Growth Inhibition & Bleaching in Higher Plants & Euglena by O-Methylthreonine; Reversal by Isoleucine

Many different conditions, lack of certain essential elements, diseases, or application of a number of toxic materials may bring about chlorosis in plants. A few organic compounds have a much more drastic effect by causing complete bleaching or albinism in the leaves of plants. Rhykerd et al. (9) reported that certain carbonic and thiocarbamic acid derivatives of hydrazine, bisthiocarbamyl hydrazine, 5aminotetrazole, and 1,2-diacetyl-3,5-diamino-1,2,3,5tetrahydro-1.2.4-thiadiazele induce albinism in plants. Bisthiocarbamyl hydrazine produced this effect because it complexed metal ions strongly. Hamner and Tukey (3) and Ready (8) found that albinism was induced by treatment with 3(a-iminoethyl) -5-methyltetronic acid and 3-nitro-4-hydroxybenzoic acid, respectively. Von Euler (13) and many other workers have noticed that streptomycin in high amounts causes complete bleaching of the leaves and stems of certain plants. The first toxic symptom produced by the well-known herbicide, 3-amino-1,2,4-triazole, is the development of young leaves devoid of chlorophyll (16). Our paper is concerned with an amino acid analog, O-methylthreonine, which causes albinism or complete bleaching of the young leaves of certain plants. We also report the results of studies carried out to determine the mode of action and the effect of O-methylthreonine on Euglena. Previously (1) we presented a preliminary report.