Mycorrhizal fungi promote the growth and development of plants, including medicinal plants. The mechanisms by which this growth promotion occurs are of theoretical interest and practical importance to agriculture. Her...Mycorrhizal fungi promote the growth and development of plants, including medicinal plants. The mechanisms by which this growth promotion occurs are of theoretical interest and practical importance to agriculture. Here, an endophytic fungus （AR-18） was isolated from roots of the orchid Anoectochilus roxburghii growing in the wild, and identified as Epulorhiza sp. Tissue-cultured seedlings of A. roxburghii were inoculated with AR-l 8 and co-cultured for 60 d. Endotrophic mycorrhiza formed and the growth of A. roxburghii was markedly promoted by the fungus. To identify genes in A. roxburghii that were differentially expressed during the symbiosis with AR-18, we used the differential display reverse transcription polymerase chain reac- tion （DDRT-PCR） method to compare the transcriptomes between seedlings inoculated with the fungus and control seedlings. We amplified 52 DDRT-PCR bands using 15 primer combinations of three anchor primers and five arbitrary primers, and nine bands were re-amplified by double primers. Reverse Northern blot analyses were used to further screen the bands. Five clones were up-regulated in the symbiotic interaction, including genes encoding a uracil phosphoribosyltransferase （UPRTs; EC 2.4.2.9） and a hypothetical protein. One gene encoding an amino acid transmembrane transporter was down-regulated, and one gene encoding a tRNA-Lys （trnK） and a maturase K （matK） pseudogene were expressed only in the inoculated seedlings. The possible roles of the above genes, especially the UPRTs and marK genes, are discussed in relation to the fungal interaction. This study is the first of its type in A. roxburghii.展开更多
rDNA internal transcribed spacer analysis(rDNA ITS)was used to study diversity of 12 representative mycorrhizal Rhizoctonia strains,which were isolated from Chinese orchids(Cymbidium)distributed in different sites and...rDNA internal transcribed spacer analysis(rDNA ITS)was used to study diversity of 12 representative mycorrhizal Rhizoctonia strains,which were isolated from Chinese orchids(Cymbidium)distributed in different sites and belonged to different ecologic types.The Blast results indicated that all these strains belonged to Epulorhiza or Tulasnella,which was fully consistent with identification as Epulorhiza with morphological method.Additionally,based on rDNA ITS sequence cluster analysis,dendrogram of Cymbidium mycorrhizal strains showed that the distributed environments and orchids species were two crucial factors that affected the specificity-relation between Chinese orchids(Cymbidium)symbiotic mycorrhizae and hosts.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 31070300, 31170314 and 31100265)the Chinese Postdoctoral Science Fund (Grant No. 20080440328)+1 种基金the Natural Science Foundation of Chongqing (Grant No. CSTC2008BB5410)the Educational Committee Science & Technology Foundation of Chongqing (Grant No. KJ090504)
文摘Mycorrhizal fungi promote the growth and development of plants, including medicinal plants. The mechanisms by which this growth promotion occurs are of theoretical interest and practical importance to agriculture. Here, an endophytic fungus （AR-18） was isolated from roots of the orchid Anoectochilus roxburghii growing in the wild, and identified as Epulorhiza sp. Tissue-cultured seedlings of A. roxburghii were inoculated with AR-l 8 and co-cultured for 60 d. Endotrophic mycorrhiza formed and the growth of A. roxburghii was markedly promoted by the fungus. To identify genes in A. roxburghii that were differentially expressed during the symbiosis with AR-18, we used the differential display reverse transcription polymerase chain reac- tion （DDRT-PCR） method to compare the transcriptomes between seedlings inoculated with the fungus and control seedlings. We amplified 52 DDRT-PCR bands using 15 primer combinations of three anchor primers and five arbitrary primers, and nine bands were re-amplified by double primers. Reverse Northern blot analyses were used to further screen the bands. Five clones were up-regulated in the symbiotic interaction, including genes encoding a uracil phosphoribosyltransferase （UPRTs; EC 2.4.2.9） and a hypothetical protein. One gene encoding an amino acid transmembrane transporter was down-regulated, and one gene encoding a tRNA-Lys （trnK） and a maturase K （matK） pseudogene were expressed only in the inoculated seedlings. The possible roles of the above genes, especially the UPRTs and marK genes, are discussed in relation to the fungal interaction. This study is the first of its type in A. roxburghii.
文摘rDNA internal transcribed spacer analysis(rDNA ITS)was used to study diversity of 12 representative mycorrhizal Rhizoctonia strains,which were isolated from Chinese orchids(Cymbidium)distributed in different sites and belonged to different ecologic types.The Blast results indicated that all these strains belonged to Epulorhiza or Tulasnella,which was fully consistent with identification as Epulorhiza with morphological method.Additionally,based on rDNA ITS sequence cluster analysis,dendrogram of Cymbidium mycorrhizal strains showed that the distributed environments and orchids species were two crucial factors that affected the specificity-relation between Chinese orchids(Cymbidium)symbiotic mycorrhizae and hosts.
