1164 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



I. Found in nature principally in solanaceous plants; Cucurbitaceae insus- 

 ceptible. Chlorotic mottling in some hosts, necrotic lesions in others as 

 result of experimental infection. Suspensions show anisotropy of flow. 



1. M armor tabaci. 



2. Marmor constans. 



II. Found in nature only in cucurbitaceous plants; Solanaceae insusceptible. 

 Only mottling as result of experimental infection. Suspensions show 

 marked anisotropy of flow. 



3. Marmor astrictum. 



III. Found only in leguminous plants. Chlorotic lesions in some varieties of the 



common snap -bean plant, necrotic lesions in others, as a result of experi- 

 mental infection. 



4. Marmor laesiofaciens . 



IV. Found in greenhouses confined to roots and lower parts of plants. Only 



necrotic lesions as result of experimental infection. Suspensions do not 

 show anisotropy of flow. 



5. Marmor lethale. 



V. Found in tomato and experimentally transmissible to a number of species of 

 plants in this and other families. Resembling the preceding in a number 

 of physical characteristics, including failure to show anisotropy of flow. 



5a. Marmor dodecahedron. 



1. Marmor tabaci Holmes. (Holmes, 

 Handb. Phytopath. Viruses, 1939, 17; 

 Musivum tabaci Valleau, Phytopath., 30, 

 1940, 822; Fhytovirus nicomosaicum 

 Thornberry, Phytopath., 31, 1941, 23.) 

 From New Latin Tabacum, early generic 

 name for tobacco. 



Common names : Tobacco-mosaic virus, 

 tomato-mosaic virus. 



Hosts : SOLANACEAE— Nicotiana 

 tabacum, L., tobacco; Lycopersicon escu- 

 lentum Mill., tomato; and Capsicum 

 frutescens L., garden pepper, among crop 

 plants; nearly all, if not all, solanaceous 

 plants can be infected, although in some 

 the virus remains localized at or near the 

 site of inoculation. PLANTAGINA- 

 CEAE — A strain of this virus has been 

 found in nature infecting Plantago lance- 

 olata L., ribgrass, P. major L. and P. 

 rugelii Dene., common broad-leaved 

 plantains. Experimental hosts are widely 

 distributed through many related families 

 of plants. 



Geographical distribution : World-wide. 



Induced disease : In most varieties of 

 tobacco, yellowish-green primary lesions, 

 followed by clearing of veins, distortion 

 and greenish-yellow mottling of newly 

 formed leaves. In Ambalema tobacco, 



no symptoms, virus being restricted to 

 inoculated leaves or those nearby. 

 Strains of tobacco showing necrotic ef- 

 fects have been produced recently. In 

 tomato, no obvious primary lesions, sys- 

 temic disease characterized by greenish- 

 yellow mottling of foliage, moderate dis- 

 tortion of leaf shape, and a reduction of 

 fruit yield not exceeding 50 per cent. If 

 some strain of potato-mottle virus (Mar- 

 mor dubiinn) is also present, a more severe 

 disease is induced; this is known as 

 double-virus streak, and is characterized 

 by systemic necrosis. In most varieties 

 of garden pepper, yellowish primary 

 lesions followed by systemic chlorotic 

 mottling. In the Tabasco pepper and its 

 recent derivatives, recovery by abscission 

 of inoculated leaf, after localization of 

 virus in necrotic primary lesions. Vacu- 

 olate intracellular inclusions are found 

 in chlorotic tissues of all hosts that show 

 distinct chlorotic mottling. 



Transmission : By slight abrasive con- 

 tacts. By inoculation of expressed juice. 

 To some extent by the aphids, Myzus 

 pseudosolani Theob., M. circumflexus 

 (Buckt . ) , Macrosiphum solanifolii Ashm . , 

 and Myzus persicae (Sulz.) {APHIDI- 

 DAE). By grafting. Through soil. 



