Sequencing And Analyses Of Mitochondrial Genome Of Cold-adapted Fungi

Cold-adapted fungi are distributed in the earth of the depths of ocean, the mountains, the north and south poles, the glacier where are the lack of some nutrition conditions and local conditions. According to the low-temperature characteristic, low temperature fungi can be divided into psychrophilic fungi and psychrotolerant fungi. They live in low-temperature environment around 0 degrees for a long time. They have to generate a unique response and defense systems, such as cold tolerance/frost resistance, the dehydration ability and hypoxia adaptation and produce antifreeze compounds, etc.The research of cold-adapted fungi are more focus in the terms of morphology, and in the molecular biology research is relatively less. GenBank includes too few fungal mitochondrial genome data at Cold-adapted fungi. This paper studied the mitochondrial genome sequence of two kinds of cold-adapted fungi Pseudogymnoascus pannorum (syn. Geomyces pannorum) and Leptosphaeria sclerotioides (syn. Phoma sclerotioides), and analyzed the sequence. Combining with the GenBank of other fungal mitochondrial genome has been sequenced data, the sequence is annotated and analyzed from size, tRNA genes, rRNA genes and the use of codes and base composition, etc. And it is analysised of the phylogenetic analysis.Pseudogymnoascus pannorum is a kind of filamentous fungi, belongs to the Ascomycota, Leotiomycetes, Pseudeurotiaceae. It is mainly distributed in Antarctica and alpine permafrost. It is a cold-adapting fungi with an optimum growth temperature between 10℃ and 20℃. It can be able to grow at temperatures as low as -5℃. It is the predominant microorganism associated with the degradation of soil-buried polyester polyurethane in landfills. Leptosphaeria sclerotioides is a kind of soil fungi, belongs to the Ascomycota,Dothideomycetes,Pleosporales,Leptosphaeriaceae. It is mainly distributed in Antarctica and other cold soil. It is a cold-adapting fungi with an optimum growth temperature between 10℃ and 20℃. It can be able to grow at temperatures as low as -4℃. It is a temperate snow mould and the brown root rot disease.Pseudogymnoascus pannorum mitochondrial genome is a circular DNA molecule and the length is 26918 bp. It is including 13 protein-coding genes, 27 tRNA genes, two ribosomal RNA gene (rnl and rns) and an open reading frame (orf120). rnl gene is contains a encoding ribosomal protein S3 (rps3) gene of open reading frame, the size of it is about 1458 bp. But compared with other fungis, Pseudogymnoascus pannorum is missing atp9 gene. Gene sequence is rnl-nad2-nad3-nad4-cox2-coxl-orf120-atp8-nad4L-nad5-cob-nad 1-atp6-rns-nad6-cox3.The Pseudogymnoascus pannorum of nad2 and nad3, nad4L and nad5 gene are closely linked, overlap each other in the mitochondrial genome. Its A+T content is very high, each section in the non-coding regions A+T the highest levels, up to 80.4%. For codon usage, in addition to the initiation codon of coxl gene is ATT, the rest are ATG, the termination codon of cob gene is the TAG, the rest are all TAA.tRNA gene length is generally around 70-90 bp, spread between protein genes and rRNA genes, adjacent tRNA genes are closely connected and some even overlap, some interval of 1 to 30 bases. Gene tRNASer, tRNASer、tRNALeu、tRNALeuLeu�'�tRNATyr have more DHC arm, they are not a typical structure of clover. Like other biological mitochondrial genome, Pseudogymnoascus pannorum tRNA secondary structure also found base mismatch in G:U and A:C.Leptosphaeria sclerotioides mitochondrial genome is still being tested, and known sequences including two ribosomal RNA gene (rnl and rns),10 protein coding gene (cox1, cox2,cox3, cob, nad1, nad2, nad4, nad4L, nad5 and nad6).