Evaluación de resistencia en una colección núcleo de parientes silvestres de Solanum tuberosum L. A Alternaria SPP. y caracterización de los aislados utilizados

Potato (Solanum tuberosum L.) is seriously affected by early blight, a disease caused by a complex of Alternaria species. This leads to a high dependency on synthetic chemical fungicides, which promotes the emergence of resistant pathogens. Therefore, identifying sources of genetic resistance in wild potato relatives emerges as a sustainable alternative to address this issue. The objective of this work was to evaluate early blight resistance in a collection of wild accessions from Uruguay, primarily composed of Solanum commersonii and Solanum malmeanum. Additionally, the study aimed to characterize the Alternaria spp. isolates used in the trials physiologically, morphologically, and molecularly. Assays were performed on detached leaves from the core collection of wild relatives using three Alternaria spp. isolates. Morphological characterization was based on evaluating growth and sporulation in two culture media, while physiological characterization assessed two different incubation methods. Molecular characterization was performed through DNA extraction and analysis of gene regions. For the resistance assays, detached leaves were inoculated with spore suspensions of 2x10⁴ esporas.mL^-1. Molecular identification revealed that isolates 2B and 12 are Alternaria alternata, while isolate 10 could not be confirmed at the species level. Regarding morphology and physiology, the isolates showed better growth and sporulation on CA medium under a 12-hour photoperiod and near-UV light, evidencing the high phenotypic plasticity of the genus. Finally, regarding the resistance trials, the absence of infection symptoms in most accessions highlights the low aggressiveness of A. alternata.