Caracterización biológica y molecular de aislados chilenos de Pseudomonas spp. asociados al cultivo de avellano europeo en Chile

Abstract

The European hazelnut (Corylus avellana L.) has gained increasing economic importance in Chile, becoming one of the country's main fruit crops. In this contexts, bacterial diseases caused by species of the genus Pseudomonas represent an emerging phytosanitary threat. The aim of this study was to biologically and molecularly characterize Pseudomonas spp. isolates obtained from European hazelnut orchards in the Maule to La Araucanía regions. A total of 92 samples from symptomatic plants were collected, and 227 bacterial strains were isolated, of which 50 were confirmed as Pseudomonas sp. through 16S rRNA gene sequencing. Subsequently, 24 isolates whose database comparisons showed genetic proximity to species reported as phytopathogens were analyzed using MLSA (genes rpoD, gyrB, acnB, and cts), identifying six main groups: Pseudomonas syringae pv. syringae (10 isolates), Pseudomonas syringae pv. tomato (4 isolates), Pseudomonas viridiflava (2 isolates), Pseudomonas lutea (1 isolate), Pseudomonas phytophila (6 isolates), and one isolate classified as Pseudomonas sp. Characterization was complemented with pathogenicity tests under controlled conditions, in which no symptoms were observed, and by LOPAT assays, which revealed profiles consistent with the molecular determinations. Additionally, copper tolerance was evaluated, identifying strains capable of withstanding concentrations equal to or higher than those applied in the field, even without prior induction. These results represent the first comprehensive approach to the diversity of Pseudomonas spp. associated with European hazelnut in Chile, providing relevant information for understanding their phytopathogenic potential and their adaptation to disease management in the field.