The Application Of Mating Type Genes In The Identification Of Indian Truffle Complexes And Mycorrhiza Synthesis

Tuber,an important genus in ectomycorrhizal ascomycetes and producing subterranean ascomata,is known as a gourmet truffle in the world.Some species among them are of high economic and ecological value,such as T.melanosporum,T.magnatum and T.indicum.The research showed that T.indicum is a complex of cryptic species from Asia,especially China.Molecular systematics revealed that T.indicum consists of at least two cryptic species,however few works were carried out to explore the morphological characteristics of the phylogenetic group of T.indicum complex.In this study,239 samples of domestic T.indicum complex specimens were analyzed for the phylogenetic analysis based on the internal transcribed spacer region(ITS)and mating type gene sequence,as well as the morphological classification to study variation of the morphological characters.In addition,because the formation of fruiting bodies(truffles)is associated with fungal mating type genes(MAT),the dynamic change of mating type gene in ectomycorrhizal seedling inoculated with T.indicum in different inoculation times were examined.The study can provide theoretical guidance for conservation and sustainable utilization of T.indicum complex.The main contents were summarized as below:1.Based on the sequences of ITS and MAT gene,the phylogenetic structure were analyzed in a large number of T.indicum complex samples.The results showed that T.indicum complex was composed of four clades,of which two clades were identified as new branches.The phylogenetic tree constructed based on MAT gene had a similar topology with that constructed by ITS and had high bootstrap value,suggesting that the MAT gene may have certain superiority in solving the taxonomic problem of the complex.2.The morphological taxonomy showed that combination of 13 morphological indexes(width of wart,shape of spore,width of summer peridium and outer peridiumand inner peridium,diameter of the asci,diameter of cell of outer peridium,diameter of hypha,height of spine of spore,width of spine of spore,spore ornamentation and distance between of spore ornamentation)could discriminate the four phylogenetic clades at high accuracy(84%).3.The dynamic change of MAT in Pinus armandii mycorrhizal seedling inoculated with T.indicum after 6,24,and 36 months in greenhouse showed that the proportion of the seedlings with MAT1-1 and MAT1-2 genes was the highest in 24 months after inoculation,suggesting that this period might be the most appropriate time for transplanting to increase the probability of mating of the strain with different mating type and fructification of truffles.