Genetic Diversity Of Cenococcum Geophilum Based On RDNA Sequence Analysis

Cenococcum geophilum is an important ectomycorrhizal fungi, and it has strong drought resistance. It has wide range of host and geographical distribution. At present, the research on the genetic diversity of Cenococcum geophilum is less in China. So the ITS region and18S rDNA intron of thirty-five chinese strains and four french strains were sequenced in this study. Combined with data from Genbank, DNA alignment was conducted and RNA secondary structure was constructed, furthermore, the genetic variation of Cenococcum geophilum was studied. The main results are as follows:1. The length of rDNA ITS sequences of Cenococcum geophilum is from422to447bp, with93%～100%similar to each other from our data and GenBank data. The ITS1and ITS2all can form stable RNA secondary structures, implying that they play roles in the post-transcriptional processing of rRNA. The phylogenetic analysis shows that Cenococcum geophilum has some degree of genetic diversity in each site, and the strains clustered togethor are from the same site. It was not found the relationship between genetic variation of Cenococcum geophilum and its host origination.2. Twenty-two out of thirty-four strains of Cenococcum geophilum from China have group-I introns in18S rDNA. Sequence analysis shows that the length of18S rDNAintron is from488to590bp from our data and GenBank data. The5’sequences of group-I introns are conserved, while the3’sequences are variable. The analysis of secondary structure indicates all the group-I introns contains ten pairing regions (P1～P10). The P5region is composed of P5, P5a, P5b, P5c and P5d, and there are two extra pairing stems (P91、 P9.2) besides the3’end of P9. The phylogenetic analysis shows that Cenococcum geophilum from the same site has genetic diversity, and geographic environment influences its genetic differentiation. It was not found the relationship between genetic diversity of Cenococcum geophilum and its host origination.3. Twenty-one out of thirty-four strains of Cenococcum geophilum from China have group-I introns in28S rDNA. Their length is from570to607bp. The5’sequences of the introns are variable, while the3’sequences are more conserved. The analysis of secondary structure indicates all the introns contained ten pairing regions (P1-P10). The P1region is composed of P1, Pla, Plb, the P5region is composed of P5, P5a, P5b, P5c.Due to no relevant reports on28S rDNA introns in Cenococcum geophilum, it is hard to perform the phylogenetic analysis.