1958 Volume 8 Issue 5 Pages 385-393
When the green broad-winged plant hopper, insect vector of the dwarf disease of Satsuma orange, is viruliferous, it shows unsound metabolisms as reported in the previous paper of the studies. The metabolisms are looked to be resulted from the disturbed metabolism of the host plant affected with the dwarf disease virus. This report deals with the observations on the interaction between the insect vector and the host plant.
(1) In the citrus plant, cytochrome oxidase is one of the terminal oxidases and its activity is considerably weakened when the plant is infected to the disease. In the insect, however, the activity of the terminal oxidase, cytochrome oxidase, is not effected by its acquisition feeding on host plant.
(2) Some organic acids belonging to the members of tricarboxylic acid cycle, viz. pyruvic acid, succinic acid and citric acid, are remarkably less in the diseased plant than in the healthy plant. Accordingly, the respiration of the viruliferous insects fed on the diseased host becomes poorer owing to the deficiency of the respiration substrates.
(3) In the citrus plant, the maximum of absorption in the wave length of ultraviolet light is found on 263mμ in ribonucleic acid (RNA) and on 266mμ in deoxyribonucleic acid (DNA). And their quantities are not differentiated, but their amounts are increased when they are diseased. In the insect, the RNA shows the maximum of absorption in 265mμ of ultraviolet light and the DNA has it in 275mμ. It is appeared that their quantities are not influenced by the virus protein.
(4) The observations are carried out on both the electrophoretic run of nucleo-protein and the ultra-violet absorption spectrum of electrophoretic patterns of the protein. Their results represent that the two fractions in citrus (I and III in Fig. 5 and 6) and three fractions in insect (I, II and III in Fig. 7 and 8) are nucleo-protein. The 4th fraction in plant and insect protein (IV in Fig. 6 and 8) is found as nucleic acid without protein, and its amount decreases in the diseased plant but increases in the viruliferous insect.
From the results above mentioned, it may be thought that the unhealthy metabolisms of the viruliferous insect are owing to the deficiency of the respiration substrates and are resulted from the decreases of the nucleo-proteins in the host plant.
