Studies on the nature of insect-transmission in plant viruses (VIII)

Abstract

For the purpose of researching differences in nucleotides between healthy and dwarf diseased rice plants, ribonucleic acid (RNA) was prepared from rice plant leaves by a modified Kirby's method. Nucleotides were then obtained from the RNA by mild alkaline hydrolysis, and their quantitative conversions were observed.(1) For preparing RNA from rice plant leaves, the procedure described in the authors' preceeding paper was again modified. According to this schedule, the rice-RNA could be obtained more rapidly and more easily, with higher purity and homogenity, both from chemical and physicochemical points of view.(2) Purine-to-pyrimidine ratio (Pu/Py) of the RNA from dwarf rice plants was from 0.88 to 1.34, the ratio of adenylic acid plus uridylic acid to guanylic acid plus cytidylic acid (A+U/G+C) of the same RNA was from 0.68 to 1.00. The values of Pu/Py and A+U/G+C of the RNA from healthy rice plants were from 0.73 to 1.28, and from 0.60 to 1.02, respectively. Nucleotide compositions of the RNA, therefore, appeared to be rather similar between healthy and diseased rice plants. It is, however, noticeable that the ratio of guanylic acid to adenylic acid is larger, and guanylic acid content of RNA is larger in the diseased plants than in the healthy plants.