A new shoot and stem disease of Eucalyptus species caused by Erwinia psidii
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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. E. 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.
KeywordsErwinia psidii Eucalyptus grandis Eucalyptus dunnii Eucalyptus globulus subsp. maidenii Eucalyptus globulus Blister bark disease Guava
We wish to thank the Tree Protection Co-operative Programme (TPCP), National Research Foundation (NRF) and the THRIP initiative of the Department of Trade and Industry for funding. We dedicate this work to Dr. Jose Garcia (deceased), a visionary tree geneticist who first brought this disease to the attention of Michael Wingfield and Nora Telechea.
- FAO (2000) Global forest resources assessment 2000—Main report: FAO Forestry paper http://www.fao.org/forestry/fo/fra/main/index.jsp
- Gryzenhout M, Wingfield BD, Wingfield MJ (2009) Taxonomy, phylogeny, and ecology of bark-infecting and tree killing fungi in the Cryphonectriaceae. APS Press, St PaulGoogle Scholar
- Hall TA (1999) BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser 41:95–98Google Scholar
- Neto JR, Robbs CF, Yamashiro T (1987) A bacterial disease of guava (Psidium guajava) caused by Erwinia psidii sp. nov. Fitopatologia Brasiliensis 12:345–350Google Scholar
- Pérez CA, Altier N, Simeto S, Wingfield MJ, Slippers B, Blanchette RA (2008) Botryosphaeriaceae from Eucalyptus and native Myrtaceae in Uruguay. Agrociencia 12:19–30Google Scholar
- Texeira ACO, Marques ASA, Ferreira MASV (2009) Low genetic diversity among pathogenic strains of Erwinia psidii from Brazil. Braz J Microbiol 40:678–684Google Scholar
- Wingfield MJ, Slippers B, Hurley BP, Coutinho TA, Wingfield BD, Roux J (2008) Eucalypt pests and diseases: growing threats to plantation productivity. South For 70:139–144Google Scholar