Genetic Diversity and Vegetative Compatibility of Fusarium solani Species Complex of Strawberry in Spain

Fusarium solani is a soilborne fungus that is a pathogen to >100 plant species. It is the causal agent of crown and root rot in strawberry. We collected 100 F. solani isolates from diseased plants and soils from two distinct geographic areas of strawberry production in Spain: plant nurseries located in the north-central region of the country and fruit production fields located in the southwestern region. The aims of this study were to accurately identify the isolates within the Fusarium solani species complex (FSSC) based on multilocus sequence typing, determine the genetic diversity and population structure of strawberry-associated FSSC based on phylogenetic analysis, and determine the vegetative compatibility among isolates in both strawberry production areas. Seven phylogenetic species, restricted to clade 3 of FSSC, were defined in the Spanish strawberry crops, showing a regional variation of species composition. Isolates from nurseries were composed of four phylogenetic species (i.e., FSSC 2, FSSC 5, FSSC 9, and an unknown FSSC species) that matched with five vegetative compatibility groups (VCGs). Isolates from fruit production fields included five phylogenetic species (i.e., FSSC 2, FSSC 3 + 4, FSSC 5, FSSC 6, and FSSC 11) distributed into 29 VCGs not correlated with phylogenetic groups. FSSC 5 and FSSC 2 were the most abundant species in nurseries and fruit production fields, respectively, and they were the only species present in both production areas. Of the 47 sequence-based haplotypes defined, no haplotypes were shared between nurseries and fruit production fields. Pathogenic isolates were present in all but FSSC 6 and FSSC 9 species, and FSSC 3 + 4 contained the higher percentage of pathogenic isolates. No relationship was observed between pathogenicity and the source of isolates (plant or soil). Generally, species present in fruit production fields showed higher genetic diversity than those present in nurseries. This work can contribute to understanding the diversity of this species complex in Spanish strawberry production areas, which will be useful for developing integrated disease management strategies.