| Miscanthus lutarioriparius a perennial high-grade C4 grass of herbaceous plants,is considered to be the most development potential of second generation biomass energy.But with the needs of modern construction,the natural habitats of M.lutarioriparius were gradually destroyed.Collection and evaluation of quality resources are beneficial to protecte the diversity of M.lutarioriparius germplasm resources and meet the breeding needs.The germplasm resources of M.lutarioriparius were collected in the middle and lower reaches of the Yangtze River in China.The main agronomic traits,phenological and geographical distributions of M.lutarioriparius were identified and analyzed.Genomic wide genotyping of 299 analyzed.The 299 germplasm resources was analyzed by SLAF simplified genome sequencing.The main results were summarized as follows:Part Ⅰ:by referring to the relevant literature and field investigation,we collected the M.lutarioriparius germplasm resources at 506 sampling points in the middle and lower reaches of the Yangtze River,which belonges to 101 countries and cities in Hubei,Hunan,Jiangxi,Anhui,Jiangsu and Zhejiang provinces with one sampling point per 3-7 km.The germplasm was planted in the flowerbank by site and plant,and also planted in 2m × 2m cells to grow.The chromosomal ploidy of 300 M.lutarioriparius germplasm resources were identified by flow cytometry and the others were identified by combining the geographic location information and phenotypic characteristics.Part Ⅱ:we set up an observation site in the city of Ezhou,Hubei province and recorded the main agronomic traits and phenological periods of 393 diploid M.lutarioriparius and 197 tetraploid M.lutarioriparius germplasm resources in 2013 to 2015 wich were planted at the spring of 2012.The effects of major agronomic traits,phenological period and geographical distribution to yield traits were analyzed by correlation analysis and path analysis.Finally,based on the value of agronomic traits in 2015,we constructed the core germplasm of M.lutarioriparius based on the value of agronomic traits in 2015.The major results were showed in follow:1.Diploid M.lutarioriparius germplasm resources are mainly distributed in the middle and lower reaches of the Yangtze River from longitude 111.44 °E to 120.11 °E and the tetraploid M.lutarioriparius germplasm resources are mainly distributed in the east and west of the Yangtze River Delta region of longitude 117.96 °E to 121.28 °E.2.The traits values of different ploidy germplasm resources were continuous distribution,and the distribution trend belongs to the normal distribution pattern likely,there was a certain degree of overlap between traits values of different ploidy M.lutarioriparius germplasm resources.The main agronomic traits of M.lutarioriparius began to grow steadily from the third year of transplanting,but still grow slowly.After entering the stable stage,the yield of diploid M.lutarioriparius germplasm resources was 364-4102 g/m2,mainly distributed in the range of 750-2500 g/m2,the mean value was 1636.91—1879.67 g/m2;The plant height was 4.25-55.00 plants/m2,the single-stem weight was 25.75-154.OOg;the plant height was 254.00485.66cm,the number of main stem nodes was 18.00-32.50;the number of lateral branches wad 0-9.00;the fourth internode length was 18.50-45.08cm;the seventh internode length was 13.60-36.30cm;stem diameter OD30 was 7.18-18.89mm;initial heading stage was from August 13 to October 2;turning yellow stage was from November 4 to December 7;period of emergence was from February 17 to March 9.The yield of tetraploid M.lutarioriparius germplasm resources was 356-2992 g/m2,mainly distributed in the range of 750-2000 g/m2;the mean value was 1362.10-1470.03 g/m2;The plant height was 9.00-77.25 plants/m2,the single-stem weight was 42.80-389.00g;the plant height was 361.00-579.40cm,the number of main stem nodes was 22.40-46.00;the number of lateral branches wad 0-14.00;the fourth internode length was 16.00-35.70cm;the seventh internode length was 17.88-34.10cm;stem diameter OD30 was 8.98-22.28mm;initial heading stage was from September 4 to October 5;turning yellow stage was from November 5 to December 11;period of emergence was from February 14 to March 6.3.There were no significant differences in the phenotypes among the geographical populations except the Lake Tai population of tetraploid M.lutarioriparius.4.The correlation analysis and path analysis of agronomic traits,phenological period and geographical distribution to yield analysis of M.lutarioriparius germplasm resources showed that the plant density,plant height/main stem length,single-stem weight and number of nodes on main stem is the significant factors affecting yield intra-different ployid M.lutarioriparius germplasm resources.5.There was no significant difference between nest core germplasm with different sampling ratios(35%、25%、15%、10%)with total population which include different ploidy M.lutarioriparius germplasm and a few M.sacchariflorus germplasm on the mean value and they could represent the diversity of the total populationPart III:14000 SNPs markers wre developed by SLAF-seq in 202 diploid M.lutarioriparius,86 tetraploid M.lutarioriparius,6 diploid M.sacchariflorus and 5 tetraploid M.sacchariflorus genotypes.Population genetic analysis was performed.The major results were showed in follow:1.The genetics analysis of M.lutarioriparius showed that tetraploid M.lutarioriparius and M.sacchariflorus clustered into one group showing a closer relationship,and diploid M.lutarioriparius cluster into one separate group.The genetic distance between in diploid M.lutarioriparius and tetraploid M.lutarioriparius is greater than that between in diploid M.lutarioriparius and M.sacchariflorus.Combined with the differences on main agronomic tiraits,phenological period,the geographical distribution between in different ploidy M.lutarioriparius,we propose a mode than diploid M.lutarioriparius was evolved from the loci mutation by diploid M.sacchariflorus,,and the tetraploid M.lutarioriparius was evolved from chromosome duplicate by diploid M.sacchariflorus or loci mutation by tetraploid M.sacchariflorus.Diploid M.lutarioriparius and tetraploid M.lutarioriparius through different evolution pathways to promote their own plants become tall and increased biomass to adapt to the habitat hydrological changes,and gradually become the dominant sacchariflorus species in their own habitat.2.Except Lake Tai population dividuals of diploid M.lutarioriparius were completely together and Hanjiang population and Yangtze River-1 population individuals of diploid M.lutarioriparius has a more obvious aggregation in the phylogenetic tree,the other geographical populations individuals mixed with each other,genotypes on individuals are less relevant to geographic location.There may be extensive genes exchanges between tetraploid M.lutarioriparius and tetraploid M.sacchariflorus in the Taihu Lake region.Part IV:Twelve SSR loci were isolated and confirmed in Miscanthus floridulus using the FIASCO.The expected heterozygosities of these markers ranged from 0.351 to 0.855,and the observed allele numbers at each locus varied between 3 and 12(with an average of 7.8).These results indicated that naturallydistributed M.floridulus plants showed high diversity and high heterozygosity at these twelve polymorphic SSR loci.At the same time,the versatility of these markers in their closely related species was examined,the results show that all 12 SSR markers were amplified and polymorphic in M.sinensis,11 amplified in M.sacchariflorus,M.lutarioriparius and M.x giganteus while 7 amplified in N.porphyrocoma.Diploid M.lutarioriparius germplasm resources are mainly distributed in the middle and lower reaches of the Yangtze River from longitude 111.44 °E to 120.11°E and the tetraploid M.lutarioriparius germplasm resources are mainly distributed in the east and west of the Yangtze River Delta region of longitude 117.96 °E to 121.28 °E。The traits values of different ploidy germplasm resources were continuous distribution.The plant heighth mean value of diploid M.lutarioriparius was 5m and tetraploid M.lutarioripariu is 4m.Combining with the genomic wide genotyping analysis,diploid M.lutarioriparius and tetraploid M.lutarioriparius were through different evolution pathways to adapt the environment.And there may be extensive genes exchanges between tetraploid M.lutarioriparius and tetraploid M.sacchariflorus in the Taihu Lake region. |
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