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Show A Modification of the Tobacco Mosaic Virus No.1 Occurring in Datura Meteloides' By H. L. BLOOD and R. D. W A TSON2 During the progress of investigations to identify various streaks of the occurring in the western states, inoculations were made on Datura meieloides, which heretofore has been considered as a host that localized the tomato tobacco mosaic virus into delimited necrotic streaks and SP0'tS and allows some other viruses in the streak complex, usually of the potato X-virus group, to develop systemically if present. Subsequently, the systemic virus component may be isolated from the infected Datura plant in a pure form. Occasionally when plants 0'f D. meteloides inoculated with the combina tion streak viruses of the tomato, consisting of ordinary tobacco mosaic and some form of potato X-virus, were allowed to stand until secondary or axillary growth had occurred, it was observed that they developed symptoms of a very pronounced and characteristic systemic infection which was not characteristic of the X-virus alone. Inoculations from such plants back to tomato resulted in the development of the same symptoms as those possessed by the original source material. Suspecting the passage of tomato mosaic through D. meteloides, inoculations were made on Datura with collections of the tomato mosaic virus from Utah fields. All the inoculated plants developed the characteristic necrotic streaks of the tobacco mosaic virus on this species, but an occasional plant developed a very characteristic systemic mottling. The virus isolated from this mottled tissue will be referred to as the systemic virus for simplicity in presentation. The symptoms which developed following inoculation on the tomato with the systemic virus could not be distinguished from the symptoms which de veloped following inoculation on the tomato with ordinary tomato mosaic virus or with Johnson's tobacco mosaic virus no, 1, which is the cause of most of the mosaic found on tomatoes in the field. However, when the sys temic virus was transferred from the tomato again to D. meteloules, it pro duced the characteristic systemic mottling immediately after the usual in cubation period on all the plants inoculated instead of the pronounced necrosis typical of the tobacco mosaic virus no. 1, while the original virus which had been perpetuated on tomato plants produced only the stem streak symptoms when inoculated on plants of D. meteloides at the same time. When these streaked plants had stood until axillary growth began, an occasional plant developed the systemic mottling. The systemic virus has been transferred through four generations of tomato and back to D. meteloides without losing its ability to produce the systemic mottling on the Datura host. In view of these results the nature of the systemic virus and its relation ship to the tobacco mosaic virus no. 1 became an interesting subject for in vestigation. Contribution from the Department of Botany and Plant 2 Pathology, Utah Agricultural Experiment Station. Agent. Division of Fruit and Vegetable Croos and Bureau of Plant In Diseases, dustry. U. S. Department of Agriculture, and Graduate Assistant, Utah Agricultural Experimental Station. resnect ively. Authorized for publication. 15 |
