Oak dieback is one of the most important diseases that presently affects the Kermanshah oak forests (West Iran). During the period from 2013 to 2015, oak trees exhibiting branch dieback were sampled, and fungal colonies resembling those of the Paecilomyces sp. were obtained from diseased tissues. Based on morphology, physiology, and phylogeny of the internal transcribed spacer rDNA, all isolates were identified as Paecilomyces formosus. Pathogenicity tests in vivo were made on 2-year-old seedlings, potted Q. brantii plants, and excised branch sections under controlled conditions. Inoculated seedlings produced characteristic symptoms, and subsequent pathogen recovery confirmed pathogenicity. We determined these to be thermophilic fungi, which may be related to warming and drought. This is the first report of Paecilomyces formosus as the causal agent of Q. brantii dieback in Iran and the world.

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Desert truffles, hypogeous Pezizales (Ascomycota), are difficult to identify due to evolutionary convergence of morphological characters among taxa that share a similar habitat and mode of spore dispersal. Also, during their symbiotic phase, these are barely distinguishable morphologically, and molecular probes are needed for their identification. We have developed a PCR-based method for the identification of Picoa juniperi and Picoa lefebvrei based on internal transcribed spacers of rDNA. Two PCR primers specific for P. lefebvrei (FLE/RLE) and two specific for P. juniperi (FJU/RJU) were designed. A collection of samples from different geographical areas representing diversity of these species were examined for unique regions of internal transcribed spacers 1, 2 and 5.8S gene of rDNA (ITS) compared to other closely related species. Annealing temperatures and extension times were optimized for each set of primers for maximum specificity and efficiency. They proved to be efficient to specifically detect the presence of P. juniperi and P. lefebvrei by PCR and neither set amplified purified DNA from other truffle species as well as some ascomycetous fungi. The partial small subunit of ribosomal DNA genes of P. juniperi were amplified with the genomic DNA extracted from Helianthemum ledifolium var. ledifolium roots by nested polymerase chain reaction (PCR) using the universal fungal primer pair ITS1/ITS4 and specific primer pair FTC/RTC, which was designed based on internal transcribed spacer 1, 2 and 5.8S gene of rDNA sequences of P juniperi. The nested-PCR was sensitive enough to re-amplify the direct-PCR product, resulting in a DNA fragment of 426 bp. The efficacy of nested-PCR showed that it could re-amplify the direct-PCR product and detect 200 fg genomic DNA.

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