Production of C-1421, an Attenuated Mutant of Pepper Strain of Tobacco Mosaic Virus

Abstract

Technique for producing attenuated mutant of pepper strain of tobacco mosaic virus (TMV-P) by heat treatment and effectiveness of the mutant for cross protection were investigated. To produce an attenuated virus mutant, heat treatment at 35C for 2 weeks, successfully adopted for tomato strains of TMV, was not successful for TMV-P because of very poor multiplication of the virus. However, when incubated at 35C for 14-16 days after pre-incubation at 25C for 3-4 days, TMV-P including some attenuated mutants multiplied sufficiently. Sweet pepper stems inoculated mechanically with TMV-P were incubated under such temperature conditions as described above. Then, an attenuated mutant of TMV-P designated C-1421 was selected from over 1, 000 single local lesion isolates on Nicotiana tabacum cv. Bright Yellow. The C-1421 was not only symptomless or very mild mottling on pepper seedlings of various cultivars, but also protective against mechanical challenge inoculation with severe TMV-P.