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Etiology

Occurrence and Characteristics of a Seed-Transmitted Potyvirus from Indian, African, and North American Guar. A. J. Hansen, Research Scientist, Agriculture Canada, Research Station, Summerland, B. C. V0H 1Z0, Canada; D. E. Lesemann, Research Scientist, Biologische Bundesanstalt fuer Land- und Forstwirtschaft, 33 Braunschweig, Messeweg 11, Federal Republic of Germany. Phytopathology 68:841-846. Accepted for publication 29 November 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-841.

Fifty seed lots of guar (Cyamopsis tetragonoloba) from India, Pakistan, the former Belgian Congo, and the USA contained a virus which induced characteristic red lesions on Chenopodium amaranticolor. Three isolates from India, Africa, and the USA showed similar flexuous-rod morphology with a normal length of 761 nm and similar pinwheel and scroll-type inclusion structures in the electron microscope. Physical properties and herbaceous host range also were similar for these isolates. The virus belongs to the potato virus Y (potyvirus) group, and can be differentiated from most other seed-transmitted legume viruses. Symptoms on Chenopodium amaranticolor and the host range differ from those of the other three legume potyviruses with identical inclusion bodies and indicate that the guar virus is different from them. Low virus concentration in all hosts and continuous loss during purification prevented serological determination of relationships. The virus presumably has been imported into North America with its guar host. Since naturally infected and inoculated guar plants remained symptomless, it tentatively has been named “guar symptomless virus” (GSV).