Vegetative Incompatibility Between Intraspecific Dikaryotic Pairings of Ganoderma Lucidum and G. Tsugae

Ganoderma zonatum Is the Causal Agent of Basal Stem Rot in Oil Palm in Colombia

Basal stem rot (BSR), caused by Ganoderma spp., is one of the most important emerging oil palm diseases in Colombia, and is restricted to two oil palm production areas in the country. To identify the causal agent of the disease, basidiocarp of oil palms affected by BSR were used to prepare isolates, and their pathogenicity was then assessed in pre-nursery plants. Four-month-old oil palm seedlings were inoculated with rubber wood (Hevea brasiliensis) blocks colonized with dikaryotic mycelia of Ganoderma. The incidence, severity, and symptoms of the pathogen were assessed. A multiregional analysis (ITS, rpb2, and tef1-α) was carried out to identify the isolates; all isolates were determined to be Ganoderma zonatum. Phylogenetic analyses with the three regions yielded concordant phylogenetic information and supported the distinction of the isolates with high bootstrap support. Seven isolates (CPBsZN-01-29, CPBsZN-02-30, CPBsZN-03-31, CPBsZN-04-34, CPBsZN-05-35, CPBsZN-06-36, and CPBsZN-07-38) were pathogenic in oil palm, with incidences greater than 90% and a maximum severity of 34%, and the highest severity index was found in isolates CPBsZN-03-31, CPBsZN-04-34, and CPBsZN-06-36. The pathogen was recovered from inoculated oil palms in all cases. This study reveals the pathogenic association of Ganoderma zonatum with BSR in Colombia.

Basidiocarp and mycelium morphology of Ganoderma lucidum Karst. Strains isolated in Hungary

Morphological, anatomical and cultural characteristics of 14 Ganoderma lucidum (Fr.) Karst strains isolated in Hungary have been investigated. Macroscopically the basidiocarps of the Hungarian strains are absolutely identical with those of described previously about the Ganoderma lucidum species-complex. Microscopic features of the fruitbodies and basidiospores showed some differences from the typical G. lucidum species. Pilocystidia, forming a homogeneous layer on the surface of the pileus, have smooth heads without protrusions and stalks not ramifying. Cell wall pillar density and width of the basidiospores also differ from that of regarded to be characteristic to G. lucidum. Although according to several authors chlamydospore formation is a characteristic feature of G. lucidum it has not been observed in mycelial cultures of the Hungarian strains. Antagonistic reactions between the Hungarian and Far Eastern G. lucidum isolates were mostly similar to the interspecific reactions between the two species G. lucidum and G. applanatum and corresponded only in a few cases to the interactions within one species. Our results suggest that the Hungarian strains significantly differ from the Far Eastern strains. To determine the taxonomic degree of this divergence genetical examinations should be carried out.

Comparison of RAPD technique and somatic incompatibility tests for the identification of Phlebiopsis gigantea strains

Somatic incompatibility assays and random amplified polymorphic DNA (RAPD) analysis were assessed and compared for use in monitoring the survival of introduced strains of Phlebiopsis gigantea, a fungal biocontrol agent used against Heterobasidion annosum root rot. Overall there was concordance between the two methods. All incompatible strains exhibited different RAPD profiles whilst compatible ones, with two exceptions, had the same RAPD profile. Somatic incompatibility tests and RAPD profiles generated by three primers, from which 11 markers were retained, could distinguish field-tested strains from among 60 strains from a population collected in Quebec and Ontario. Furthermore, both methods allowed us to clearly demonstrate the presence of inoculated strains 1 year after treatment. The combined use of these techniques provides a valuable tool for discriminating between different P. gigantea strains and conducting epidemiological studies. Key words: Heterobasidion annosum, vegetative incompatibility, random amplified polymorphic DNA, biological control, Pinus resinosa.