Pseudomonas syringae causing bacterial canker on apple trees in Brazil

Leonardo Araujo,Marcelo Gravina De Moraes,Valmir Duarte,Yuliet Franco Cardoza

doi:10.1590/1678-4499.20200246

Abstract

ABSTRACT In March 2016, wilt and shoot blight were observed on five-year-old apple trees (Malus domestica) cultivar Maxi Gala in a commercial orchard in Sao Joaquim city, state of Santa Catarina, Brazil. Isolation on culture media, biolog, biochemical, LOPAT tests, and whole genome sequencing were performed. Koch’s postulates were fulfilled on apple stems, leaves and fruits. The taxonomic position of a representative strain was determined by in silicoDNA-DNA hybridization using the Genome-to-Genome Distance Calculator which showed 93.9% similarity with Pseudomonas syringae. Results of biolog and biochemical tests did not match those expected for pv. papulans, morsprunorum or syringae. To our knowledge this is the first report of P. syringae causing bacterial canker in commercial apple orchards in Brazil.

Highlights

In March 2016, wilt and shoot blight were observed on five-year-old apple trees (Malus domestica) cultivar Maxi Gala in a commercial orchard in São Joaquim city, state of Santa Catarina, Brazil
Diseases of fruit trees caused by strains of the Pseudomonas syringae complex are of major concern in fruit producing areas worldwide, because they are exceedingly difficult to control, and result in economic losses (Kennelly et al 2007; Young 2010; Gomila et al 2017)
Infection of woody tissue is important on fruit trees because cankers eventually girdle and kill branches, thereby resulting in loss of fruiting surface and tree death (Kennelly et al 2007; Perminow et al 2018)

Summary

Introduction

In March 2016, wilt and shoot blight were observed on five-year-old apple trees (Malus domestica) cultivar Maxi Gala in a commercial orchard in São Joaquim city, state of Santa Catarina, Brazil. Diseases of fruit trees caused by strains of the Pseudomonas syringae complex are of major concern in fruit producing areas worldwide, because they are exceedingly difficult to control, and result in economic losses (Kennelly et al 2007; Young 2010; Gomila et al 2017). The P. syringae complex that infect fruit trees exhibit commonalities and differences in life cycles and the symptoms they incite, as well as in their biochemical, immunological, and molecular characteristics (Kerkoud et al 2002; Kennelly et al 2007; Young 2010; Gomila et al 2017; Gašić et al 2018).

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