Identificação de bactérias causadoras de podridões moles de ocorrência nos estados do Pará e Minas Gerais

Abstract

The pectinolytic bacteria causing soft rot are responsible for large economic losses in the cultivation of a wide range of host plants, both in the field and in commercialization, especially in hot and humid climate regions. Thus, the present work aimed to identify different isolates of bacteria that cause soft rot in vegetables, fruit trees and some ornamental species using biochemical, physiological, molecular tests and sequencing of the 16S rDNA region. The experiments were performed at the Phytopathology Laboratory of Embrapa Amazônia Oriental and at the Laboratory of Plant Bacteriology of the Federal University of Lavras (DFP / UFLA) from 2017 to 2018. A total of 39 bacterial isolates were obtained from the states of Pará and Minas Gerais. The biochemical and physiological tests were: Gram, catalase, oxidase, Pectate degradation, potato and green pepper rot, anaerobiosis, growth at 37 ° C in NA medium, growth in YDC medium and sensitivity to erythromycin. In the polymerase chain reaction technique, oligonucleotides 1491f / L1RA / L1RG were used to differentiate Pectobacterium carotovorum from Dickeya chrysanthemi, Br1f / L1RA / L1RG specific for Pectobacterium carotovorum subsp. brasiliensis, ERWFOR and CHRREV for identification of the species Dickeya chrysanthemi. For the Nested-PCR, the primer pair EXPCCR / EXPCCF and INPCCR / INPCCF were used in the first and second reaction, respectively, to detect P. carotovorum subsp. carotovorum. For the sequencing of the 16S rDNA region primers 27F and 1492R were used. In general, biochemical and molecular methods were not efficient for the identification of the isolates. However, by the sequencing of the 16S rDNA region it was possible to identify the majority of isolates causing soft rot obtained in the study at the genus level.