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Etiology

Host Range, Symptomatology, and Electron Microscopy of a Persistent, Aphid-Transmitted Virus from Alfalfa in Michigan. George Thottappilly, Department of Entomology and Pesticide Research Center, Michigan State University, East Lansing, MI 48824; Ya-Chu (Judy) Kao(2), Gary R. Hooper(3), and James E. Bath(4). (2)(3)(4)Department of Entomology and Pesticide Research Center, Michigan State University, East Lansing, MI 48824. Phytopathology 67:1451-1459. Accepted for publication 16 June 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1451.

A virus that was transmitted from alfalfa plants in Michigan resembles pea leaf roll virus because of its transmission in a persistent manner by the pea aphid, Acyrthosiphon pisum, nontransmissibility after sap-inoculations, and its host reactions on Vicia faba, V. sativa, Pisum sativum, Trifolium incarnatum, T. subterraneum, Cicer arietinum, Lens esculenta, Medicago hispida, and Phaseolus vulgaris. Medicago sativa infected with this virus usually was symptomless, but virus could be readily recovered from it. None of 20 nonleguminous species tested was susceptible to this virus. Electron microscopy of several infected host plants revealed spherical, viruslike particles (diameter 23 ± 1.5 nm) in some phloem cells. Virus concentration in cells varied from a few, widely scattered particles to dense masses; occasionally, crystalline arrays of these particles were observed. Identity of the virus in relation to other persistent, aphid-borne viruses which cause yellowing, leaf-rolling, and stunting in leguminous plants was reviewed.