Etiologia da prodridão mole de hortaliças na Região Oeste do Pará

Abstract

Due to the lack of information on the etiological agents of soft rot in the western region of Pará, the characterization and analysis of the cultural, phytopathogenic and genetic diversity of bacterial isolates obtained from collections of vegetables with symptoms of the disease in commercial gardens in Belterra was carried out, Santarém and Mojuí dos Campos in 2019, with the aim of characterizing the isolates in terms of cultural, pathogenic, and molecular diversity. The semiselective isolation method was carried out using pepper fruits with subsequent cultivation of the bacteria in CPG culture medium (Casein, Peptone, and Glucose). The colonies obtained were characterized and preserved in distilled and sterilized water. A total of 75 isolates were obtained, with the most frequent cultural characteristics being the circular shape (70 %), convex elevation (52 %), rough structure (66 %), shattered glass appearance (73 %), translucent shine (90 %), color cream (74%) and moist consistency (90%), with equivalent lobed (47%) and wavy (45%) edges, characteristics like species of the genus Pectobacterium, Dickeya and others within the family Enterobacteriaceae. By means of Euclidean analysis using the UPGMA method, based on cultural variability, the isolates were differentiated into 29 cultural types, with 17 isolates not forming a cluster and the largest group obtained sheltered 18 isolates, which characterizes a high cultural diversity of the isolated in this study. As for pathogenicity, five groups were formed, of which 77% of the isolates were characterized as pathogenic to potatoes, peppers, onions, and carrots, which shows a lack of specificity of the isolates in the region. Thirty-eight isolates were selected for molecular analysis using REP, ERIC, and BOX - PCR, which were grouped using the UPGMA method and Jaccard analysis for dendrogram formation. There was high genetic variability of the isolates, with 35 genetic groups at 70% similarity. Observing the cultural, pathogenic, and genetic variability, we concluded that there is a possibility that there is more than one bacterial species or genus causing soft rot in the western region of Pará. Thus, further investigations through molecular analyzes are necessary to elucidate the genera and species involved in soft rot in vegetables in the western region of Pará.