Incidencia Y Caracterizacion: Morfologica, Patogenica Y Genetica De Alternaria Spp. En Cultivos De Cebolla Del Sur De Puerto Rico

Resumen del Libro

Incidence and characterization of Alternaria spp. associated with foliar lesions at different stages of the onion cycle were determined. The study was carried out at commercial and experimental fields in the southern area of Puerto Rico. Alternaria spp. incidence increased in sixty-day-old onion plants of cultivars Mercedes and Excalibur. Sixty two percent of selected Alternaria isolates were placed within a semi-arborescent group, not described taxonomically. Other isolates were identified as: Alternaria alli, A. destruens, A. palandui, A. tenuissima and Pleospora eturmiuna. Pathogenicity tests conducted in vitro and in the field revealed that A. alli, A. tenuissima, Alternaria sp. semi-arborescent and Pleospora eturmiuna were pathogenic to onions, been A. alli the most virulent. Molecular characterization of Alternaria isolates was determined using RAPD-PCR, ITS1-5.8S-ITS2 region of the ribosomal DNA, and sequences analysis of region ITS1-ITS4 of rDNA.