全世界芒屬植物約有20種，主要分布於亞洲到太平洋，為多年生的C4禾本科植物，具有快速生長及高生物量（biomass）特性，為熱門的替代生質能源。在台灣，芒草從低海拔到中高海拔、農耕地到旱地、重金屬汙染地到火山硫磺地與海邊高鹽環境皆有分布，可見芒草對環境的耐受性極高，能利用其他植物無法利用之棲地。先前研究顯示植物內共生菌能增加植物對逆境的耐受性，推測芒草於不同逆境下應有不同的優勢共生菌群與之共生，協助生長，對抗逆境。
本研究採集來自不同逆境之中國芒（Miscanthus sinensis）複合群成熟葉片，利用流式細胞儀檢測其倍體數，估算基因體大小。再取根部組織，以16S rRNA序列當作分子條碼，探究其根部內共生菌多樣性。樣本經PCR增幅後，進行次世代定序（Next-generation sequencing），所得序列經程式BLASTClust集結產生OTUs（Operational taxonomic units），對資料庫進行比對，得到物種資訊，再利用MEGAN分析根內共生菌的多樣性。結果顯示: 中國芒複合群主要為二倍體，基因體大小約5.4 Gbp/2C。在高溫硫磺逆境白背芒根內優勢共生菌群為Actinomycetales （62.6%）；在銅汙染逆境白背芒根內優勢共生菌群為Burkholderiales （32.3%）；在高鹽逆境八丈芒根內優勢共生菌群為Rhizobiales （27.5%）；在低溫逆境高山芒根內優勢共生菌群為Pseudomonadales （74.1%）；在無特殊逆境白背芒根內優勢共生菌群為Burkholderiales （53.4%）、無特殊逆境甜根子草（外群） 根內優勢共生菌群為Burkholderiales （45.3%）。芒草根內優勢共生菌如何影響芒草的生長，增加對逆境的耐受性，則仍有待進一步的研究。

Miscanthus plants mainly distributed in Asia and Pacific islands, possesses 20 species worldwide. The plant is a perennial C4 grasses, with rapid growth and high biomass features as the alternative biofuel feedstock. In Taiwan, Miscanthus sp. can be seen on the river band, costal area, agricultural land, sulfur and copper contaminated area, and mountainous area from low elevation to high elevation. Miscanthus have high tolerance to environmental stresses and take advantage of the habitat that other plants can’t use. Studies have shown that endophytes can promote host plant growth and increase the tolerance of stress, suggesting Miscanthus under stress should symbiosis with different bacterial community. We assessed the nuclear DNA content and ploidy levels of Miscanthus sinensis complex by flow cytometry. The majority of M. sinensis genotypes are diploid and genome size is 5.4 Gbp/2C. This study also targeted 16S rRNA gene as barcode to possess next-generation sequencing and profile endophytes in Miscanthus roots under abiotic stresses. Result revealed the most dominant endophyte group inside root of M. sinensis var. glaber under sulfur-oxidation stress is Actinomycetales （62.6%）, M. sinensis var. glaber under copper contaminated stress is Burkholderiales （32.3%）, M. sinensis var. condensatus under salt stress is Rhizobiales （27.5%）, M. sinensis var. transmorrisonensis under cold stress is Pseudomonadales （74.1%）, M. sinensis var. glaber without specific stress is Burkholderiales （53.4%）, Saccharum spontaneum without specific stress is Burkholderiales （45.3%）. Mechanisms of endophytes increase the tolerance of stress of Miscanthus remain to be further studied.

Amann, R.I., Ludwig, W. and Schleifer, K.H. （1995） Phylogenetic identification and in situ detection of individual microbial cells without cultivation. Microbiol Reviews, 59, 143-169.
Arshad, M. and Frankenberger Jr, W.T. （1997） Plant growth-regulating substances in the rhizosphere: microbial production and functions. Advances in Agronomy, 62, 45-151.
Bacon, C.W. and Hinton, D.M. （2002） Endophytic and Biological Control Potential of Bacillus mojavensis and Related Species. Biological Control, 23, 274-284.
Barka, E.A., Nowak, J. and Clément, C. （2006） Enhancement of chilling resistance of inoculated grapevine plantlets with a plant growth-promoting rhizobacterium, Burkholderia phytofirmans strain PsJN. Applied and Environmental Microbiology, 72, 7246-7252.
Botsford, J.L. （1984） Osmoregulation in Rhizobium meliloti: inhibition of growth by salts. Archives of Microbiology, 137, 124-127.
Botsford, J.L. and Lewis, T.A. （1990） Osmoregulation in Rhizobium meliloti: production of glutamic acid in response to osmotic stress. Applied and environmental microbiology, 56, 488-494.
Bray, J.R. and Curtis, J.T. （1957） An ordination of the upland forest communities of southern Wisconsin. Ecological Monographs, 27, 325-349.
Chabot, R., Antoun, H. and Cescas, M.P. （1996） Growth promotion of maize and lettuce by phosphate-solubilizing Rhizobium leguminosarum biovar phaseoli. Plant and Soil, 184, 311-321.
Chaintreuil, C., Giraud, E., Prin, Y., Lorquin, J., Bâ, A., Gillis, M., de Lajudie, P. and Dreyfus, B. （2000） Photosynthetic bradyrhizobia are natural endophytes of the African wild rice Oryza breviligulata. Applied and Environmental Microbiology, 66, 5437-5447.
Chiang, Y.C., Schaal, B.A., Chou, C.H., Huang, S. and Chiang, T.Y. （2003） Contrasting selection modes at the Adh1 locus in outcrossing Miscanthus sinensis vs. inbreeding Miscanthus condensatus （Poaceae）. American Journal of Botany, 90, 561-570.
Chou, C.H., Chiang, T.Y. and Chiang, Y.C. （2001） Towards an integrative biology research: a case study on adaptive and evolutionary trends of Miscanthus populations in Taiwan. Weed Biology and Management, 1, 81-88.
Chou, C.H., Chiang, Y.C. and Chiang, T.Y. （2000） Genetic variability and phytogeography of Miscanthus sinensis var. condensatus, an apomictic grass, based on RAPD fingerprints. Canadian Journal of Botany, 78, 1262-1268.
Chou, C.H., Huang, S., Chen, S.H., Kuoh, C.S., Chiang, T.Y. and Chiang, Y.C. （1999） Ecology and Evolution of Miscanthus of Taiwan. National Science Council Monthly, 27, 1158-1169.
Clayton, D.W. and Renvoize, S.A. （1986） Genera graminum: grasses of the World.
Clifton-Brown, J.C., Chiang, Y.C. and Hodkinson, T.R. （2008） Miscanthus: genetic resources and breeding potential to enhance bioenergy production. Genetic improvement of bioenergy crops. Springer, New York, 273-294.
Clifton‐Brown, J.C., Breuer, J. and Jones, M.B. （2007） Carbon mitigation by the energy crop, Miscanthus. Global Change Biology, 13, 2296-2307.
Compant, S., Reiter, B., Sessitsch, A., Nowak, J., Clément, C. and Barka, E.A. （2005） Endophytic colonization of Vitis vinifera L. by plant growth-promoting bacterium Burkholderia sp. strain PsJN. Applied and Environmental Microbiology, 71, 1685-1693.
Dobbelaere, S., Vanderleyden, J. and Okon, Y. （2003） Plant growth-promoting effects of diazotrophs in the rhizosphere. Critical Reviews in Plant Sciences, 22, 107-149.
Głowacka, K., Jeżowski, S. and Kaczmarek, Z. （2009） Polyploidization of Miscanthus sinensis and Miscanthus x giganteus by plant colchicine treatment. Industrial Crops and Products, 30, 444-446.
Govindarajan, M., Balandreau, J., Kwon, S.W., Weon, H.Y. and Lakshminarasimhan, C. （2008） Effects of the inoculation of Burkholderia vietnamensis and related endophytic diazotrophic bacteria on grain yield of rice. Microbial Ecology, 55, 21-37.
Handelsman, J., Rondon, M.R., Brady, S.F., Clardy, J. and Goodman, R.M. （1998） Molecular biological access to the chemistry of unknown soil microbes: a new frontier for natural products. Chemistry & Biology, 5, 245-249.
Hodkinson, T.R. and Renvoize, S. （2001） Nomenclature of Miscanthus x giganteus （Poaceae）. Kew Bull, 56, 759-760.
Huson, D.H., Auch, A.F., Qi, J. and Schuster, S.C. （2007） MEGAN analysis of metagenomic data. Genome Research, 17, 377-386.
Huson, D.H., Richter, D.C., Mitra, S., Auch, A.F. and Schuster, S.C. （2009） Methods for comparative metagenomics. BMC Bioinformatics, 10, S12.
Imada, T., Hiruma, N., Isawa, T., Noda, M., Kurihara, Y. and Kon, M. （2006） Pest control method for grass family plants using endophytic bacteria, pest control material, and seed bound to the pest control material: US Patent.
James, E.K. and Olivares, F.L. （1998） Infection and colonization of sugar cane and other graminaceous plants by endophytic diazotrophs. Critical Reviews in Plant Sciences, 17, 77-119.
Kaneko, T., Minamisawa, K., Isawa, T., Nakatsukasa, H., Mitsui, H., Kawaharada, Y., Nakamura, Y., Watanabe, A., Kawashima, K. and Ono, A. （2010） Complete genomic structure of the cultivated rice endophyte Azospirillum sp. B510. DNA Research, 17, 37-50.
Kumar, S., Nei, M., Dudley, J. and Tamura, K. （2008） MEGA: a biologist-centric software for evolutionary analysis of DNA and protein sequences. Briefings in Bioinformatics, 9, 299-306.
Lazarovits, G. and Nowak, J. （1997） Rhizobacteria for improvement of plant growth and establishment. HortScience, 32, 188-192.
Le Rudulier, D., Strom, A., Dandekar, A., Smith, L. and Valentine, R. （1984） Molecular biology of osmoregulation. Science, 224, 1064-1068.
Manson, J.M., Rauch, M. and Gilmore, M.S. （2008） The commensal microbiology of the gastrointestinal tract. In GI Microbiota and Regulation of the Immune System: Springer, pp. 15-28.
Mattos, K.A., Pádua, V.L., Romeiro, A., Hallack, L.F., Neves, B.C., Ulisses, T.M., Barros, C.F., Todeschini, A.R., Previato, J.O. and Mendonça-Previato, L. （2008） Endophytic colonization of rice （Oryza sativa L.） by the diazotrophic bacterium Burkholderia kururiensis and its ability to enhance plant growth. Anais da Academia Brasileira de Ciências, 80, 477-493.
Mei, C. and Flinn, B.S. （2010） The use of beneficial microbial endophytes for plant biomass and stress tolerance improvement. Recent Patents on Biotechnology, 4, 81-95.
Misaghi, I. and Donndelinger, C. （1990） Endophytic bacteria in symptom-free cotton plants. Phytopathology, 80, 808-811.
Mitra, S., Klar, B. and Huson, D.H. （2009） Visual and statistical comparison of metagenomes. Bioinformatics, 25, 1849-1855.
Montaña, J.S., Jiménez, D.J., Hernández, M., Ángel, T. and Baena, S. （2012） Taxonomic and functional assignment of cloned sequences from high Andean forest soil metagenome. Antonie van Leeuwenhoek, 101, 205-215.
Murray, D.C., Bunce, M., Cannell, B.L., Oliver, R., Houston, J., White, N.E., Barrero, R.A., Bellgard, M.I. and Haile, J. （2011） DNA-based faecal dietary analysis: a comparison of qPCR and high throughput sequencing approaches. PloS One, 6, e25776.
Murray, M. and Thompson, W.F. （1980） Rapid isolation of high molecular weight plant DNA. Nucleic Acids Research, 8, 4321-4326.
Muyzer, G. and Ramsing, N.B. （1995） Molecular methods to study the organization of microbial communities. Water Science and Technology, 32, 1-9.
Nishiwaki, A., Mizuguti, A., Kuwabara, S., Toma, Y., Ishigaki, G., Miyashita, T., Yamada, T., Matuura, H., Yamaguchi, S. and Rayburn, A.L. （2011） Discovery of natural Miscanthus （Poaceae） triploid plants in sympatric populations of Miscanthus sacchariflorus and Miscanthus sinensis in southern Japan. American Journal of Botany, 98, 154-159.
Oliveira, A., Stoffels, M., Schmid, M., Reis, V., Baldani, J. and Hartmann, A. （2009） Colonization of sugarcane plantlets by mixed inoculations with diazotrophic bacteria. European Journal of Soil Biology, 45, 106-113.
Osborn, T.C., Chris Pires, J., Birchler, J.A., Auger, D.L., Jeffery Chen, Z., Lee, H.S., Comai, L., Madlung, A., Doerge, R. and Colot, V. （2003） Understanding mechanisms of novel gene expression in polyploids. Trends in Genetics, 19, 141-147.
Palleroni, N. （1992） Introduction to the family Pseudomonadaceae. The Prokaryotes, 3, 3071-3085.
Patten, C.L. and Glick, B.R. （2002） Role of Pseudomonas putida indoleacetic acid in development of the host plant root system. Applied and Environmental Microbiology, 68, 3795-3801.
Rayburn, A.L., Crawford, J., Rayburn, C.M. and Juvik, J.A. （2009） Genome size of three Miscanthus species. Plant Molecular Biology Reporter, 27, 184-188.
Reinhold, B., Hurek, T., Niemann, E.G. and Fendrik, I. （1986） Close association of Azospirillum and diazotrophic rods with different root zones of Kallar grass. Applied and Environmental Microbiology, 52, 520-526.
Rothballer, M., Eckert, B., Schmid, M., Fekete, A., Schloter, M., Lehner, A., Pollmann, S. and Hartmann, A. （2008） Endophytic root colonization of gramineous plants by Herbaspirillum frisingense. FEMS Microbiology Ecology, 66, 85-95.
Saravanan, V., Madhaiyan, M., Osborne, J., Thangaraju, M. and Sa, T. （2008） Ecological occurrence of Gluconacetobacter diazotrophicus and nitrogen-fixing Acetobacteraceae members: their possible role in plant growth promotion. Microbial Ecology, 55, 130-140.
Savolainen, V., Cowan, R.S., Vogler, A.P., Roderick, G.K. and Lane, R. （2005） Towards writing the encyclopaedia of life: an introduction to DNA barcoding. Philosophical Transactions of the Royal Society B: Biological Sciences, 360, 1805-1811.
Schmidt, S., Blom, J.F., Pernthaler, J., Berg, G., Baldwin, A., Mahenthiralingam, E. and Eberl, L. （2009） Production of the antifungal compound pyrrolnitrin is quorum sensing‐regulated in members of the Burkholderia cepacia complex. Environmental Microbiology, 11, 1422-1437.
Shannon, C.E. （1948） A mathematical theory of communication. The Bell Technical Journal, 27, 379-423.
Simon, C. and Daniel, R. （2011） Metagenomic analyses: past and future trends. Applied and Environmental Microbiology, 77, 1153-1161.
Simpson, E.H. （1949） Measurement of diversity. Nature, 163-688.
Strobel, G.A. and Castillo, U.F. （2007） Endophytic streptomycetes from higher plants with biological activity: US Patent.
Suman, A., Gaur, A., Shrivastava, A. and Yadav, R. （2005） Improving sugarcane growth and nutrient uptake by inoculating Gluconacetobacter diazotrophicus. Plant Growth Regulation, 47, 155-162.
Sun, Y., Cheng, Z. and Glick, B.R. （2009） The presence of a 1‐aminocyclopropane‐1‐carboxylate （ACC） deaminase deletion mutation alters the physiology of the endophytic plant growth‐promoting bacterium Burkholderia phytofirmans PsJN. FEMS Microbiology Letters, 296, 131-136.
Taghavi, S., Garafola, C., Monchy, S., Newman, L., Hoffman, A., Weyens, N., Barac, T., Vangronsveld, J. and van der Lelie, D. （2009） Genome survey and characterization of endophytic bacteria exhibiting a beneficial effect on growth and development of poplar trees. Applied and Environmental Microbiology, 75, 748-757.
Tamura, K., Peterson, D., Peterson, N., Stecher, G., Nei, M. and Kumar, S. （2011） MEGA5: molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Molecular Biology and Evolution, 28, 2731-2739.
Team, R.C. （2008） R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing, 1-1731.
Turnbaugh, P.J. and Gordon, J.I. （2008） An invitation to the marriage of metagenomics and metabolomics. Cell, 134, 708-713.
Uyttebroek, M., Vermeir, S., Wattiau, P., Ryngaert, A. and Springael, D. （2007） Characterization of cultures enriched from acidic polycyclic aromatic hydrocarbon-contaminated soil for growth on pyrene at low pH. Applied and Environmental Microbiology, 73, 3159-3164.
Vasileiadis, S., Puglisi, E., Arena, M., Cappa, F., Cocconcelli, P.S. and Trevisan, M. （2012） Soil bacterial diversity screening using single 16S rRNA gene V regions coupled with multi-million read generating sequencing technologies. PloS One, 7, e42671.
Vaughan, E.E., Schut, F., Heilig, H., Zoetendal, E.G., de Vos, W.M. and Akkermans, A.D. （2000） A molecular view of the intestinal ecosystem. Current Issues in Intestinal Microbiology, 1, 1-12.
Woese, C.R. and Fox, G.E. （1977） Phylogenetic structure of the prokaryotic domain: the primary kingdoms. Proceedings of the National Academy of Sciences, 74, 5088-5090.
Yanni, Y.G., Rizk, R.Y., El-Fattah, F.K.A., Squartini, A., Corich, V., Giacomini, A., de Bruijn, F., Rademaker, J., Maya-Flores, J. and Ostrom, P. （2001） The beneficial plant growth-promoting association of Rhizobium leguminosarum bv. trifolii with rice roots. Functional Plant Biology, 28, 845-870.
Yap, S. and Lim, S. （1983） Response of Rhizobium sp. UMKL 20 to sodium chloride stress. Archives of Microbiology, 135, 224-228.
Yasuda, M., Isawa, T., Shinozaki, S., Minamisawa, K. and Nakashita, H. （2009） Effects of colonization of a bacterial endophyte, Azospirillum sp. B510, on disease resistance in rice. Bioscience, Biotechnology, and Biochemistry, 73, 2595-2599.
Yu, S., Ke, L., Wong, Y. and Tam, N. （2005） Degradation of polycyclic aromatic hydrocarbons by a bacterial consortium enriched from mangrove sediments. Environment International, 31, 149-154.
Zaurov, D., Bonos, S., Murphy, J., Richardson, M. and Belanger, F. （2001） Endophyte infection can contribute to aluminum tolerance in fine fescues. Crop Science, 41, 1981-1984.