An atypical Lettuce mosaic virus isolate breaking mo12 gene in lettuce

ABSTRACT Lettuce (Lactuca sativa L.) belongs to the Asteraceae family and is one of the most consumed vegetables in Brazil. Lettuce mosaic virus (LMV) an important virus for this crop and, currently, its main control form is based on the utilization of genotypes carrying the tolerance gene mol1 and mol2. A LMV isolate from Botucatu (SP), named LMV-Bot, was identified considering its biological and molecular characteristics. When inoculated in distinctive lettuce varieties that classifies LMV pathotypes (‘Ithaca - Mo gene’, ‘Malika – mol1’ ‘Vanguard 75 - Mo and mol2’ and ‘Salinas 88 - mo12’), LMV-Bot induced symptoms only in ‘Salinas 88’. The N’ terminal coding region for the capsid protein was amplified and sequenced, and its phylogenetic position revealed similarity to two Brazilian isolates named BR6 and A435 and to another one from France (FR4). However, LMV-Bot did not fit in the sub-group Most and Common. Results suggest that, although rare, atypical isolates of LMV are found in nature infecting lettuce and can break the resistance gene mol2.