Genetic variability within n-rDNA region of ectomycorrhizal isolates originating from temperate ecosystems

Abstract

Identification of Ectomycorrhiza Fungi (ECM) based on morphological characters has been laborious and time consuming, especially samples collected from the environment. Additionally, due to its microscopic nature and limited morphological characters, intraspecies variation is difficult to detect. In view of this, this study aimed at confirming the earlier identification of these fungi, which was based on morphological characters, and also to find suitable molecular restriction fragment length polymorphism (RFLP) markers for the identification of ECM fungi up to the level of species or isolates as part of an expandable database of RFLP patterns of the internal transcribed spacers (ITS) region of ECM fungi. Mycelia of 14 species of ectomycorrhizal fungi representing five genera were isolated in pure culture and characterized by morphological and molecular methods. Molecular identification was performed by analysis of the internal transcribed spacers of the nuclear encoded ribosomal RNA (n-RNA) gene region using restriction fragment length polymorphism (RFLP). The region was first amplified by polymerase chain reaction with specific primers and then cleaved with different restriction enzymes. The degree of polymorphism, although extensive, proved inadequate for proper identification of most of the isolates. Depending on the restriction enzymes used, the genera or species could be grouped on the basis of common fragment patterns, thereby confirming the potential of the small subunit (SSU)-ITS region in PCR-RFLP in molecular characterization and identification of ectomycorrhizal fungi. Based on the results of this study, congruent of morphology and molecular RFLP analysis is recommended for characterization of species/strain of ectomycorrhizal fungi.

Keywords: Classification, diversity, ectomycorrhizal fungi, ecosystem, ribosomal DNA

African Journal of Biotechnology Vol. 12(22), pp. 3390-3398