First report of host b-protein appearance in response to a fungal infection in tobacco

Infection of leaves of N. tabacum cv. Burley 49, cv. Judy's Pride Burley and the reciprocal hybrids with Thielaviopsis basicola induced necrotic local lesions and host specific b-proteins, whose number varied with the cultivar of tobacco studied. TMV infection induced the same b-proteins, together with necroses, in cv. Burley 49 and the hybrids but none in the susceptible cultivar Judy's Pride Burley. A new b-protein (b 1′) of mol. wt similar to b 1, b 2 and b 3 (15 500) was detected in the hybrids after fungal and virus infection. Evidence is presented that the information coding for this protein must have come from the cultivar Judy's Pride Burley. The link between b-protein synthesis and resistance to parasites in tobacco is underlined.