FAMILY MARMORACEAE 



1171 



6. Marmor erodens Holmes. (Holmes, 

 Handb. Phytopath. Viruses, 1939, 40; 

 Foliopellis erodens Valleau, Phytopath., 

 30, 1940, 825.) From Latin erodere, to 

 erode or gnaw away. 



Common name: Tobacco-etch virus. 



Hosts : SOLAN ACE AE— Capsicum 

 frutescens L., pepper ; Datura stramonium. 

 L., Jimson weed ; Lycopersicon esculentum 

 Mill., tomato; Nicotiana tabacum L., to- 

 bacco; Petunia sp., petunia; Physalis 

 heterophylla Xees. 



Geographical distribution: United 

 States. 



Induced disease : In tobacco, systemic 

 mild-mottling chlorosis, with traces of 

 necrotic etching; intranuclear crystalline 

 inclusions and intracytoplasmic granular 

 and amorphous inclusions that tend to 

 crystallize, forming needle-shaped bire- 

 fringent bodies, 2 to 10 microns in length. 



Transmission : Experimentally, by My- 

 zus persicae (Sulz.), M. circumfiexus 

 (Buckt.), Aphis rhamni Boyer, A.fabae 

 (Scop.), and Macrosiphum gei (Koch) 

 (APHIDIDAE) ; by inoculation of ex- 

 pressed juice. 



Serological relationships : Precipitin re- 

 actions with homologous antisera, but 

 no cross -react ions with tobacco-mosaic 

 virus, tobacco -ringspot virus, potato - 

 mottle virus, potato aucuba-mosaic virus, 

 potato mild-mosaic virus, hs'oscyamus- 

 mosaic virus, potato-veinbanding virus, 

 or pea-mosaic virus. 



Immunological relationships : Protects 

 tobacco against subsequent infection by 

 potato-veinbanding virus and hyoscya- 

 mus-mosaic virus. In mixed infections, 

 't suppresses and replaces these two 

 viruses. 



Thermal inactivation : At 53 to 55° C in 

 10 minutes. 



Filterability : Passes Pasteur-Cham- 

 be rland Li, not La, filter candle. 



Other properties : Sedimentation con- 

 stant 820° = 170 X 10-13 cm. sec.-i dyne-i. 

 Concentrated preparations show aniso- 

 tropy of flow, indicating elongated parti- 

 cle shape. 



Literature : Bawden and Kassanis, Ann. 



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

 Cornell Agr. Exp. Sta. (Ithaca), Mem. 

 96, 1925; Holmes, Phytopath., 32, 1942, 

 1058-1067; Johnson, Kentuckj^ Agr. Exp. 

 Sta., Res. Bull. 306, 1930. 



Strains : A distinctive severe -symptom 

 strain, i.solated from plants infected in 

 nature and studied intensively, has been 

 distinguished from the type, var. vulgare 

 H. {loc. cit., 40), by the varietal name : 



6a. Marmor erodens var. severum H. 

 {loc. ci'L, 41 ) . Differing from the type by 

 a tendency to induce more pronounced 

 necrotic etching and a greater stunting 

 effect in infected tobacco. 



7. Manner hyoscyami spec. nov. 

 From Xew Latin Hyoscyamus, genus 

 name of plant from which this virus was 

 first isolated. 



Common names : Hyoscyamus-mosaic 

 virus, Hy. Ill virus, Hyoscyamus-III- 

 disease virus. 



Hosts : SOLAN AC EAE— Hyoscyamus 

 niger L., henbane. Experimentally, also 

 Nicotiana tabacum L., tobacco. 



Insusceptible species -.CUCURBITA- 

 CEAE — Cucumis sativus L., cucumber. 



Geographical distribution: England. 



Induced disease : In henbane, chlorotic 

 clearing of veins followed by yellow-mot- 

 tling mosaic. 



Transmission: By inoculation of ex- 

 pressed juice to dilutions of 10^^. B3- 

 aphids, Myzus persicae (Sulz.), M. cir- 

 cumfiexus (Buckt.), and Macrosiphum 

 solanifolii Ashm. (= M. gei Koch) 

 (APHIDIDAE). 



Serological relationships : Several iso- 

 lates of this virus give mutual cross- 

 precipitin reactions but no precipitation 

 occurs when antiserum prepared with this 

 virus is mixed with cucumber-mosaic 

 virus, tobacco-etch virus, or potato-vein- 

 banding virus. 



Immunological relationships : Xo im- 

 munity with respect to this virus is in- 

 duced in tobacco by previous infection 

 with cucumber-mosaic virus. Potato- 

 veinbanding virus is unable to multiply 

 in the presence of this virus and is re- 

 placed by it. Tobacco-etch virus pro- 



