Abstract:
Many species in the Cryphonectriaceae
cause diseases of trees, including those in the genera
Eucalyptus and Syzygium. During disease surveys on
these trees in southern China, fruiting structures
typical of fungi in the Cryphonectriaceae and
associated with dying branches and stems were
observed. Morphological comparisons suggested that
these fungi were distinct from the well known
Chrysoporthe deuterocubensis, also found on these trees
in China. The aim of this study was to identify these
fungi and evaluate their pathogenicity to Eucalyptus
clones/species as well as Syzygium cumini. Three
morphologically similar fungal isolates collected
previously from Indonesia also were included in the
study. Isolates were characterized based on comparisons
of morphology and DNA sequence data for the
partial LSU and ITS nuclear ribosomal DNA, btubulin
and TEF-1a gene regions. After glasshouse trials to select virulent isolates field inoculations were
undertaken to screen different commercial Eucalyptus
clones/species and S. cumini trees for susceptibility
to infection. Phylogenetic analyses showed that the
Chinese isolates and those from Indonesia reside in a
clade close to previously identified South African
Celoporthe isolates. Based on morphology and DNA
sequence comparisons, four new Celoporthe spp. were
identified and they are described as C. syzygii, C.
eucalypti, C. guangdongensis and C. indonesiensis.
Field inoculations indicated that the three Chinese
Celoporthe spp., C. syzygii, C. eucalypti and C.
guangdongensis, are pathogenic to all tested Eucalyptus
and S. cumini trees. Significant differences in the
susceptibility of the inoculated Eucalyptus clones/
species suggest that it will be possible to select diseasetolerant
planting stock for forestry operations in the
future.
