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MANUAL OF DETERMINATIVE BACTERIOLOGY 



FAMILY III. ANNULACEAE HOLMES. 



(Handb. Phytopath. Viruses, 1939, 97.) 



Viruses of the Ringspot Group, causing diseases usually characterized by necrotic; 

 or chlorotic spotting with concentric-ring lesions and eventual recovery from obvious 

 disease with non-sterile immunity. Hosts, higher plants; vectors unknown. There 

 is a single genus. 



Genus I. Annulus Holmes. 



{hoc. cit., 97.) 



Characters those of the family. Generic name from Latin annulus, a ring. 

 The type species is Annulus tahaci Holmes. 



Key to the species of genus Annulus. 



I. Found occurring naturally in the Western Hemisphere. 



A. In tobacco. 



1. Annulus tahaci. 



2. Annulus zonatus. 



3. Annulus orae. 



4. Annulus apertus. 



B. In potato. 



5. Annulus dubius. 



C. In delphinium. 



6. Anmtlus delphinii. 

 II. Old World species. 



7. Annulus bergerac. 



1. Annulus tabaci Holmes. (Handb. 

 Phytopath. Viruses, 1939, 98; Marmor 

 anularium McKinney, Jour. Washington 

 Acad. Sci., S4, 1944, 327.) From New 

 Latin Tahacum, early generic name for 

 tobacco. 



Common names: Tobacco-ringspot vi- 

 rus, green ringspot virus, yellow ringspot 

 virus, ring spot No. 1 virus. 



Hosts: SOLA N ACE AE—Nicotiana 

 tahacum L., Petunia violacea Lindl., 

 Solanum tuberosum L. CUCURBITA- 

 CEAE — Cucumis sativus L. Experimen- 

 tally this virus has been found capable of 

 infecting many species of plants in a large 

 number of families ; these include all 

 tested species of the SOLAN ACE AE, 

 SCROPHULARIACEAE, COMPOSI^ 

 TAE, and CUCURBIT ACEAE. 

 Many species of the LEGUMINOSAE 

 are susceptible and one, Vigna sinensis 

 (L.) Endl., is used as an indicator plant 

 for quantitative measurement because 

 it displays conspicuous reddish -brown 

 necrotic lesions around points of initial 

 infection. 



Geographical distribution: United 

 States. 



Induced disease : In tobacco, necrotic 

 ring-like primary lesions, followed by 

 secondary necrotic rings on younger 

 leaves. Subsequently, affected plants 

 recover. After recovery from obvious 

 disease, virus content of plants is only 10 

 to 20 per cent of that of recently infected 

 jjlants. Some varieties may show 

 mosaic-like patterns in young leaves 

 at 16°C. 



Transmission : By inoculation of e.x- 

 dressed juices. Through about 20 per 

 cent of seeds from diseased petunia 

 plants. Not by dodder, Cuscuta campes- 

 tris Yuncker (CONVOLVULACEAE). 



Serological relationships : Induces the 

 formation of specific precipitating anti- 

 bodies when injectetl into bloodstream of 

 rabbit. 



Immunological relationships : Recov- 

 ered tobacco plants are not susceptible to 

 reinfection with this virus but are readily 

 infected with Annulus zonatus or A. orae. 

 This virus produces primary lesions on 



