Igor Henrique de Lima Costa, Gloria Emperatriz Suqui Carchi, Isabela Schneid Kroning, Maria Fernanda Fernandes Siqueira, Frederico Schmitt Kremer, Wladimir Padilha da Silva, C\u00e2ndida Renata Jacobsen de Farias, Alvaro Renato Guerra Dias<\/p>\n
This study reports the first case of\u00a0Alternaria alternata<\/em>\u00a0causing soft rot in pitaya (Hylocereus polyrhizus<\/em>) fruits in Rio Grande do Sul, Brazil. Symptomatic fruits were collected from a commercial orchard, and the pathogen was isolated, characterized both morphologically and molecularly (using ITS, GAPDH, and TEF-1\u03b1\u00a0loci<\/em>), and tested for pathogenicity. The colonies exhibited mycelial growth of 5.24\u00a0\u00b1\u00a00.35\u00a0cm after 7 days and 8.08\u00a0\u00b1\u00a00.37\u00a0cm after 14 days, with olive gray centers and light brown edges. The obclavate or obpyriform conidia had transverse (1\u20136) and longitudinal (0\u20133) septa, with a short apical tip (5\u201322.5\u00a0\u03bcm). Molecular analysis revealed 100\u00a0% similarity with\u00a0A. alternata<\/em>\u00a0sequences in GenBank, confirming the pathogen via phylogenetic analysis. Pathogenicity tests produced dark brown, depressed lesions with a clear halo, characteristic of the disease, confirming Koch’s postulates. The 100\u00a0% incidence in commercial fruit crops resulted in significant economic losses, exacerbated by favorable weather conditions. Thus, this study presents the first evidence of\u00a0A. alternata<\/em>\u00a0associated with post-harvest soft rot in pitaya fruits in Brazil, underscoring the need for management strategies to reduce waste and economic losses along the production chain.<\/p>\n