Inoculation experiments of several plant viruses to duck-weed (Spirodela polyrhiza)

Abstract

Multiplication of ordinary strain of tobacco mosaic virus (TMV) on the duck-weed (Spirodela polyrhiza) was reported in the preceding paper (Komuro and Iwaki 1964). This paper deals with the results of inoculation experiments of several plant viruses and virus strains to the duck-weed.
1. Yellow strain and tomato streak strain of TMV, both isolated from tomato in 1963, were also proved to multiply on the duck-weed without symptom as in the case of ordinary strain of TMV.
2. On the other hands, cucumber mosaic virus, alfalfa mosaic virus, turnip mosaic virus, and also watermelon mosaic virus were not able to multiply on the same weed even in repeated inoculation experiments.
3. Potato virus X (PVX) was ascertained to multiply on the duck-weed from the following experimental results.
i) Quantity of PVX recovered from the inoculated duck-weeds on the 3rd day and 5th day after inoculation was small, but it became larger on the 10th and 20th day after inoculation.
ii) Vein-clearing sometimes appeared on the fronds of inoculated duck-weed, and the virus was recovered in larger quantities from the fronds showing vein-clearing than from those having no symptoms.
iii) Particles, about 500mμ in length, were observed in the juice of fronds inoculated with PVX under an electron microscope, while no such particles were recognized in the juice of healthy fronds.
iv) Juice from duck-weed having vein-clearing symptom showed the precipitation reaction when it was mixed with PVX-antiserum.
4. Ordinary strain of TMV, and PVX both multiplied on the duck-weed, when these two viruses were inoculated at the same time, and the fronds of duck-weed showed vein-clearing, as in the inoculation with PVX alone.