FAMILY ANNULACEAE 



1213 



leaves of plants immune to reinfection 

 with A. bergerac. 



Thermal inactivation : At 68° C in 10 

 minutes. 



Filterability : Passes V, X, and perhaps 

 W Berkefeld filters. 



Other properties: Particle size esti- 

 mated by filtration experiments as about 

 19 millimicrons. Sedimentation con- 

 stant, 820° = 115 X 10-13 cm. sec.-i 

 dyne~i. Infective in dilutions of 10"^ 

 after purification. Inactivated in 1 hour 

 below pH 3 or above pH 10.8. Recovered 

 plants of tobacco contain 0.002 mg of 

 virus per gram, recently infected plants 

 about 6 times as much. Optimum con- 

 ditions for retaining infectivity of stored 

 virus include suspension in 0.01 M phos- 

 phate buffer at pH 7 and storage at 4° C. 



Literature: Fenne, Phytopath., 21, 

 1931, 891-899; Fromme et al., ibid., 17, 

 1927, 321-328; Henderson, ibid., 21, 1931, 

 225-229; Henderson and Wingard, Jour. 

 Agr. Res., J,3, 1931, 191-207; Price, Con- 

 trib. Boyce Thompson Inst., I^, 1932, 

 359-403; Phytopath., 26, 1936, 503-529; 

 Am. Jour. Bot., 27, 1940, 530-541; Am. 

 Naturalist, 74, 1940, 117-128; Priode, Am. 

 Jour. Bot., 15, 1928, 88-93 ; Stanley, Jour. 

 Biol. Chem., 129, 1939, 405-428, 429-436; 

 Stanley and Wyckoff, Science, 85, 1937, 

 181-183; Valleau, Kentucky Agr. Exp. 

 Sta., Bull. 327, 1932; Wingard, Jour. Agr. 

 Res., 37, 1928, 127-153; Woods, Contrib. 

 Boyce Thompson Inst., 5, 1933, 419-434. 



Strains: A number of distinctive 

 strains have been collected in nature and 

 studied experimentall}'. The following 

 have been given varietal names to dis- 

 tinguish them from the type, var. vir- 

 giniensis H., loc. cit., 98: 



la. Annulus tabaci var. kentuckiens is 

 H. {loc. cit., 99). Differing from the 

 typical strain in producing less necrosis 

 and less stunting in tobacco. (Price, 

 Phytopath., 26, 1936, 665-675; Valleau, 

 Kentucky Agr. Exp. Sta., Bull. 327, 

 1932.) 



lb. Annulus tabaci var. avratus H. 

 {loc. cit., 100). Secondary lesions in 



tobacco at first yellow spots or rings, be- 

 coming necrotic subsequently. Recov- 

 ery less complete than with type, abnor- 

 mal yellowing of old leaves tending to 

 persist. (Chester, Phytopath., 25, 1935, 

 686-701; Price, Phytopath., 26, 1936, 

 665-675; Valleau, Kentucky Agr. Exp. 

 Sta., Bull. 327, 1932; Phytopath., 29, 

 1939, 549-551.) 



2. Annulus zonatus H. {loc. cit., 101 j. 

 From Latin zonatus, zonate. 



Common names : Tomato -ringspot vi- 

 rus, ring spot No. 2 virus. 



Hosts : SOLAN AC EAE—Nicotiana 

 tabacum L., tobacco. Experimentally 

 this virus has been found to infect many 

 species of plants in a large number of 

 families. 



Geographical distribution : United 

 States. 



Induced disease : In tobacco, zonate 

 necrotic primary lesions and, temporarily, 

 secondary lesions of the same type; 

 recovery with specific, non-sterile im- 

 munity. In tomato, systemic infection, 

 yellowish-green or necrotic ring-like le- 

 sions; stunting. 



Transmission: By inoculation of ex- 

 ])ressed juice. 



Immunological relationships : Recov- 

 ered plants are immune to reinfection but 

 are still susceptible to Annulus tabaci, A. 

 bergerac, and several mosaic -type viruses 

 that have been tested. 



Thermal inactivation : At 55 to 60° C 

 in 10 minutes. 



Filterability : Passes Gradocol mem- 

 brane 100 millimicrons in average pore 

 diameter. Particle size estimated as 50 

 millimicrons or less. 



Literature : Price, Phytopath., 26, 1936 

 665-675 ; Am. Jour. Bot., 27, 1940, 530-541 . 



3. Annulus orae H. {Holmes, loc. cit., 

 103; Tractns orae Valleau, Phytopath., 

 30, 1940, 826.) From Latin ora, edge, in 

 reference to occurrence of induced dis- 

 ease near edge of tobacco fields. 



Common name : Tobacco-streak virus. 



Hosts : SOLA NA CEAE— Nicotiana 



tabacum L., tobacco. Experimentally, a 



