This study was conducted to develop superior hybrids of Pleurotus ostreatus with di-mono and mono-monoka-ryon crosses. Random Amplified Polymorphic DNA-PCR (RAPD-PCR) was used to compare its mitochondrial DNA profiles of hybrids using specific primers designed from microsatellite markers of Pleurotus salmoneo-stramineus. A total of fifty-six dikaryon-monokaryon hybrids were sampled for RAPD-PCR experiments and the results show that twenty-four hybrids were dikaryon and thirty-one hybrids were monokaryon. Interestingly, one hybrid was an intermediate form with the DNA profiles that are different from those of its parents. The DNA profiles from eighty-eight monokaryon-monokaryon hybrids were also analyzed by RAPD-PCR. The results of mitochondria DNA profiles show that seventy-one hybrids are the same to one of their parents, but seventeen hybrids show DNA profiles of both parents.

Mycoviruses have been found in many fungal species including mushrooms. Double-stranded (ds) RNA genomes were common type in mycoviruses, but single-stranded (ss) RNA mycoviruses were also reported in some fungal species. Sequencing analysis using cDNA cloning experiments revealed that mycoviruses can be classified into several different virus families such as Totiviridae, Hypoviridae, Partitiviridae and Barnaviridae etc. Because the nucleotide sequence data that are available in these days are very limited in a number of mycoviruses, the existence of more diverse viral groups in fungi are currently expected. In this review, we selected four different fungal groups, which were considered as the model systems for mycovirus related studies in both plant pathogenic fungi and edible mushroom species, and discussed about their molecular characteristics of diverse mycoviruses. The plant pathogenic fungi introduced here were Cryphonectria parasitica and Helminthosporium victoriae and the edible mushroom species were Agaricus bisporus and Pleurotus ostreatus.