Abstract
Several isolates derived from the attenuated tomato strain of tobacco mosaic virus TMV-L11A were examined in regard to their degree of cross protection against a virulent virus TMV-AK1 in tomato cultivar Momotaro with resistance gene Tm-1/+ to TMV. Among four attenuated isolates tested, L11A Fukushima gave the highest degree of cross protection. The other isolates, in decreasing order of the degree of cross protection, were as follows: L11A Chiba, L11A237 and L11A. In addition, L11A Fukushima prevented appreciable symptom development even under high temperature conditions in the summer, whereas L11A and L11A237 did not.
