Small-sporedAlternariaspp. (sectionAlternaria) are common pathogens on wild tomato species

Abstract

AbstractThe wild relatives of modern tomato crops are native to South America. These plants occur in habitats as different as the Andes and the Atacama Desert and are to some degree all susceptible to fungal pathogens of the genusAlternaria. Alternariais a large genus. On tomato, several species cause early blight, leaf spot, and other diseases.We collectedAlternaria-like infection lesions from the leaves of eight wild tomato species from Chile and Peru. Using molecular barcoding markers, we characterized the pathogens. The infection lesions were caused predominantly by small-spored species ofAlternariaof the sectionAlternaria, likeA. alternata, but also byStemphyliumspp.,Alternariaspp. from the sectionUlocladioides, and other related species. Morphological observations and an infection assay confirmed this. Comparative genetic diversity analyses show a larger diversity in this wild system than in studies of cultivatedSolanumspecies.AsA. alternatahas been reported to be an increasing problem on cultivated tomato, investigating the evolutionary potential of this pathogen is not only interesting to scientists studying wild plant-pathosystems. It could also inform crop protection and breeding programs to be aware of potential epidemics caused by species still confined to South America.