ABSTRACT Early blight caused by large‐spored Alternaria spp. is one of the major limiting diseases affecting tomato production globally, including the Baltic region. The present study is the first report of Alternaria spp. (section Porri ) affecting tomatoes in Latvia, Lithuania and Estonia, identified using a multilocus phylogenetic approach with phenotypic assays. Maximum‐likelihood and Bayesian inference phylogenetic analyses of the internal transcribed spacer regions 1 and 2 and the intervening 5.8S nuclear ribosomal DNA (ITS), glyceraldehyde‐3‐phosphate dehydrogenase ( gapdh ), RNA polymerase II second largest subunit ( rpb2 ), translation elongation factor 1‐α ( tef1 ) and Alternaria major allergen ( alt a 1 ) genes were used to identify 79 Alternaria spp. strains from tomatoes. Alternaria linariae was confirmed as a major pathogen (52%, n = 41) whereas Alternaria protenta (9%, n = 7) followed by A. solani (5%, n = 4) had the lowest isolation frequency. Moreover, 34% of fungal strains represented two novel taxa from Alternaria section Porri and were described as A. emajogiana sp. nov. and A. gialosensis sp. nov. isolated from tomatoes in Estonia and Latvia, respectively. Both new species were phylogenetically distinct from closely related A. lanceolatae , A cepae , A. montanica , A. carthamicola and A. scorzonerae , differing from them by the size of the conidial body and beak, and the number of transverse septa. Pathogenicity assays on 8‐week‐old tomato seedlings confirmed the five isolated Alternaria species as causal agents of tomato early blight; both A. emajogiana sp. nov. and A. gialosensis sp. nov. were moderately to highly aggressive on their host of origin.
Dučkena et al. (Sun,) studied this question.