Study On Genetic Diversity Among Ganoderma Isolates Cultivated In China And Molecular Detection Of Ganoderma Species

Ganoderma species have been used as Chinese traditional medicine with a longhistory. In recent years, the cultivation of Ganoderma was developed quickly, with thegermplasm resource becoming more and more plentiful. But the isolates cultivated in Chinaare presently in chaos seriously. With the aim to study the genetic relationship amongGanoderma isolates cultivated in China with different commercial names, and to developmethod for identification of Ganoderma species, genetic diversity among 74 Ganodermaisolates (50 isolates cultivated in China from 13 provinces, 3 wild isolates and 21 foreignisolates) was investigated using ITS sequencing firstly. According to the result ofphylogenetic analysis based on ITS sequences, 38 isolates (23 isolates cultivated in Chinaand 15 foreign isolates) were chosen to investigate if theβ-tubulin gene was suitable forexploring the genetic relationships among Ganoderma strains. And then phylogeneticanalysis of 38 isolates were explored based on partialβ-tubulin gene sequences andcombined sequences. Furthermore, PCR-based detection of some Ganoderma species weremade based on ITS. The major results are as follows:1. Phylogenetic analysis of Ganoderma isolates based on ITS sequences revealed that all74 isolates were separable into eight groups. Isolates cultivated in China, 50 in all, weredistributed between five of these groups. And phylogenetic analysis of partialβ-tubulingene sequences revealed that 38 isolates were separable into nine groups, the 23isolates cultivated in China were distributed between six of these groups. The resultsproduced by ITS andβ-tubulin gene separately are similar, with isolates ofGtsugae-Goerstedii Group in ITS tree clustered into two separate groups: GtsugaeGroup and Goerstedii Group inβ-tubulin tree.2. Phylogenetic analysis of combined ITS and partialβ-tubulin gene sequences revealedthat 38 isolates were separable into nine groups, the 23 isolates cultivated in China weredistributed between six of these groups. It is similar to the results produced by ITS andβ-tubulin gene separately, and bootstrap values are increased for most groups, with isolates of the subgenus Elfringia, the section Phaeonema and the section Ganodermaclustered into three separate groups. Therefore, we believe phylogenetic studies withmultiple genes is more effective.3. Comparison of the sequences obtained from all the isolates indicated that the thirdnucleotide of certain individual codons, and the intron region, of theβ-tubulin genewere prone to have a high rate of nucleotide substitution, thereby providing a largenumber of potentially variable characters for phylogenetic analysis. Therefore, webelieve theβ-tubulin gene is suitable for exploring the genetic relationships amongGanoderma strains.4. Genetic diversity between members of the subgenus Elfringia, section Phaeonema andsection Ganoderma was clearly manifest, but was less evident among members of thesection Ganoderma since most of these isolates were clustered together in only onesubsection.5. Based on phylogenetic analysis of rDNA ITS sequences, seven pairs of specific primerswere designed for identifying the six Ganoderma species by PCR.