A new shoot and stem disease of Eucalyptus species caused by Erwinia psidii

Abstract

A serious disease of green, actively expanding stems of young Eucalyptus grandis, E. dunnii, E. globulus and E. globulus subsp. maidenii has been observed in plantations in Uruguay and Argentina during the course of the past 10 years. The symptoms of the disease are unlike those previously observed on any species of Eucalyptus. In this study, we describe the symptoms of this new disease and determine its cause. A diagnostic feature of the disease is a red discolouration of the young host tissue and blistering of the young bark leading to rapid shoot death. A bacterium was consistently isolated from the stem blisters on to nutrient agar, purified and a selection of six strains were subjected to standard phenotypic tests and 16S rRNA-, gyrB-and rpoB-gene sequencing. The ability of these strains to induce a hypersensitive reaction (HR) was tested on tobacco and a pathogenicity tests were undertaken on a E. grandis clone. The bacterium was found to be identical to Erwinia psidii. Strains inoculated into tobacco produced a HR within 36 h and discolouration of internal shoot tissue was observed in the inoculated E. grandis clone. Eucalyptus psidii is known to cause die-back of guava (Psidium guajava) which is closely related to Eucalyptus, also belonging to the Myrtaceae. Results of this study suggest that E. psidii has undergone a host shift to become an important pathogen of Eucalyptus spp. that are widely planted in South America to sustain important paper and pulp industries.

Species of Mycosphaerellaceae and Teratosphaeriaceae on native Myrtaceae in Uruguay: evidence of fungal host jumps

“…Eucalyptus where these trees are grown as exotics (Coutinho et al 2011;Glen et al 2007;Rodas et al 2005) , there are far fewer examples of movement of apparently introduced Eucalyptus pathogens to native plants (Crous and Groenewald, 2005). Results of this study provide important new information that this movement is far more common than has been previously thought.…”

Enfermedades bacterianas de eucaliptos: Estado actual del conocimiento

“…eucalypti por Truman (1974) (Coutinho et al 2002) y más recientemente en el año 2014 a Xanthomonas vasicola Vauterin (Coutinho et al 2014). En Argentina y Brasil, se ha identificado a Erwinia psidii como agente causal del tizón apical bacteriano (Arriel et al 2014, Coutinho et al 2011. En Uruguay se confirmó a E. psidii y P. ananatis como causales de esta enfermedad en eucalipto (FAO 2006, Coutinho et al 2011.…”

“…En Argentina y Brasil, se ha identificado a Erwinia psidii como agente causal del tizón apical bacteriano (Arriel et al 2014, Coutinho et al 2011. En Uruguay se confirmó a E. psidii y P. ananatis como causales de esta enfermedad en eucalipto (FAO 2006, Coutinho et al 2011. Además, en Uruguay se reportó a Enterobacter cowanii Inoue, especie aislada junto a P. ananatis a partir de síntomas de tizón bacteriano en Eucalyptus grandis.…”

“…Erwinia psidii se la ha observado principalmente en plantaciones jóvenes, de 6 a 24 meses de edad (Coutinho et al 2011). Existen algunos estudios epidemiológicos de E. psidii en Psidium guajava L., que demuestran la capacidad de la bacteria de sobrevivir en restos de vegetales infectados, en el suelo y/o asociada a hospederos secundarios.…”

“…La detección de E. psidii en Eucalyptus spp. es considerada un salto de hospedero desde el monte nativo, específicamente desde Psidium guajava, hacia las plantaciones comerciales de eucalipto (Coutinho et al 2011).…”