Botrytis eucalypti, a novel species isolated from diseased Eucalyptus seedlings in South China

Abstract

Eucalyptus has become a preferred species for the production of industrial products and also for the protection of natural forests in South China. Many diseases affect these trees, both on plantations and in nurseries. One such disease in Eucalyptus nurseries is grey mould caused by a species of Botrytis. Symptoms of grey mould were recently observed on stems and leaves of Eucalyptus urophylla × Eucalyptus grandis seedlings in nurseries in ZhanJiang, GuangDong Province, South China. Diseased stems and leaves were covered with mycelium, conidiophores, and conidia of the causal pathogen. The fungus was identified on the basis of DNA sequence comparisons and morphological features, and its pathogenicity was tested on three Eucalyptus clones. Based on sequence comparisons of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA and partial DNA sequences of five nuclear gene regions, glyceraldehyde-3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), necrosis and ethylene-inducing proteins (NEP1 and NEP2), combined with morphological characteristics and culture growth rate, the fungus represents a previously undescribed species of Botrytis. This undescribed species is phylogenetically and morphologically closely to Botrytis cinerea and B. pelargonii, but can be distinguished from them by DNA sequences of HSP60, RPB2, NEP1, and NEP2 gene regions, conidial characteristics, and culture growth rate. Here, a description of the fungus, designated as Botrytis eucalypti sp. nov., is provided. The results of in vitro leaf inoculation tests demonstrate that B. eucalypti is virulent on all three tested E. urophylla × E. grandis clones.