1172 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



tects against this virus and replaces it in 

 mixed infections. 



Thermal inactivatibn : At 58° C in 10 

 minutes. 



Filterability : Passes Chamberland Li, 

 but not Ls, filter candles. 



Other properties : Concentrated solu- 

 tions show anisotropy of flow. Yield of 

 virus, 1 to 3 mg per liter of juice expressed 

 from diseased tobacco plants. 



Literature : Bawden and Kassanis, Ann. 

 Appl. Biol., 28, 1941, 107-118; Hamilton, 

 ibid., 19, 1932, 550-567; Sheffield, ibid., 

 25, 1938, 781-789; Watson and Roberts, 

 Proc. Roy. Soc. London, Ser. B, 127, 1939, 

 543-576. 



8. Marmot upsilon comb. nov. {Mar- 

 mor cucumeris var. vpsilon Holmes, loc. 

 cit., 33; Murialba vcnataenia Valleau, 

 Phytopatli., 30, 1940, 824.) From Greek 

 name of the letter Y, sometimes used to 

 denote this virus. 



Common names : Potato -veinbanding 

 virus, potato virus Y. 



Hosts: SOLAN ACE AE—Solaniim tu- 

 herosxim L., potato; Nicotiana tabacum 

 L., tobacco. Experimentally, also Ltj- 

 cium barbariim L. 



Geographical distribution: England, 

 France, United States, Brazil. Rare in 

 Scotland and part of Ireland. 



Induced disease : In some potato varie- 

 ties, leaf drop and necrotic stem-streak; 

 in others, no signs of disease; in still 

 others, chlorotic mottling with or without 

 necrosis. In combination with strains 

 of the ]3otato-mottle virus {Marmor 

 dubium), this virus causes rugose mosaic, 

 a common and destructive double-virus 

 disease . 



Transmission: By inoculation of ex- 

 pressed juice. By aphid, Myzus persicae 

 (Sulz.); experimentally, also by Aphis 

 rhamni Boyer (synonym for Aphis ab- 

 breviata Fatch) (APHIDIDAE). 



Serological relationships : Precipitin re- 

 actions with homologous antisera. No 

 cross reactions with tobacco-mosaic virus, 

 tobacco-etch virus, hyoscyamus -mosaic 

 virus, potato-mottle virus, potato mild- 

 mosaic virus, potato aucuba-mosaic virus, 

 tobacco-ringspot virus, or common pea- 

 mosaic virus. Reported cross reaction 

 with cucumber-mosaic virus needs con- 

 firmation. 



Immunological relationships : A mild 

 strain protects against subsequent infec- 

 tion with the typical virus. This virus 

 is suppressed and replaced by hyoscya- 

 mus-mosaic virus and by tobacco-etch 

 virus in mixed infections. 



Thermal inactivation : At 52° C in 10 

 minutes. 



Filterability : Passes with difficulty 

 through Gradocol membrane of 42 milli- 

 micron average pore diameter. 



Other properties : Inactivated by dry- 

 ing. 



Literature: Dennis, Nature, 14-2, 1938, 

 154; Johnson, Phytopath., 25, 1935, 

 650-652; Jones and Vincent, Jour. Agr. 

 Res., 55, 1937, 69-79; Kassanis, Ann. 

 Appl. Biol., 29, 1942, 95; Koch, Phyto- 

 path., 28, 1933, 319-342; Kramer and Sil- 

 berschmidt, Arquivos Inst. Biol., Sao 

 Paulo, Brazil, 11, 1940, 165-188; Salaman, 

 Nature, 139, 1937, 924; Smith, Proc. Roy. 

 Soc, Ser. B, 109, 1931, 251-267; Smith and 

 Dennis, Ann. Appl. Biol., 27, 1940, 65-70. 



Key to the species of the Cuciunber -Mosaic Virus Group. 



Viruses relatively susceptible to heat inactivation, requiring less than 10 minutes 

 at 85 to 90° C for complete inactivation. Not replacing potato-veinbanding virus in 

 mixed infections. 



I. Infecting both dicotyledonous and monocotyledonous plants. 



9. Marmor cucumeris. 

 II. Infecting dicotyledonous, but not monocotyledonous, plants. 



10. Marmor solani. 



11. Marmor aucub a. 



12. Marmor umbelliferarum . 



