| Stylosanthes is one of the most important high quality legumes in the subtropical and subtropical regions. Their characteristics have high yield,drought resistance,barren tolerance and wide adaptability. Now they have become the dominant forage in the southern area of China. Parents in this study have significant differences in some major agronomic characters, Stylosanthes guianensis TPRC1979 and Stylosanthes guianensis TPRCR273 hydride to create offspring Fi. 202 F2 offspring was gained by F1 self. The agronomic traits,drought resistance and salt tolerance of parents,F1 and F2 generations segregating population were observed and analyzed in order to explore the genetic characteristics. SNP markers were used to construct high density genetic map of F2 segregating population, and QTL mapping of related traits was performed. The main conclusions of this study are as follows:(1) Construct SNP genetic map. Joinmap 4.1 was used to construct the genetic linkage map. Linkage analysis identified 10 linkage groups with a total of 13661 markers.The genetic distance was 1854.5716cM. At present, the map is the most makers and the highest density.(2) Continue to observe the agronomic traits of F2 population. After the agronomic traits were determined by the research group in 2015. In 2016, agronomic traits including the natural plant height, leaf length, width, the number of primary branches, the longest branch and the fresh weight per plant of F2 segregating population were measured. The results showed that the average coefficient of variation of 9 agronomic characters was 33.62%, and the coefficient of variation of fresh and dry weight were the highest. The normality test showed that the 6 agronomic traits accord with or approximately accord with normal distribution. The results of correlation analysis, regression analysis and principal component analysis showed that the number of primary branches was the most important factor affecting yield, followed by plant height. They all had a positive effect.(3) Stress resistance analysis of F2 generation mapping population at seedling stage.Study on drought resistance and salt tolerance of F2 segregating population. The same 7 indexes were selected and analyzed in the two studies, and the relative value reflected their adaptability under the adverse circumstances. The results of cluster analysis showed that all of 160 kinds of materials in the drought resistance experiment, 83 kinds of materials in the salt tolerance test and 61 kinds of materials in the two experiments showed some hybrid vigor. The strains with strong resistance to stress accounted for more than 60% of the total.(4) QTL mapping of quality traits and agronomictraits in Stylosanthes. The results of the whole genome scaned by MapQTL 5 software combined with the genetic map showed that 77 QTLs for the three morphological traits were checked. Among them, there were 14 QTLs controlling FC, 14 QTLs controlling IFS, while the value of LOD was greater than 3.There were 49 QTLs controlling FBS, while the value of LOD was greater than 9. The results of the whole genome scaned showed that 157 QTLs for the eight quality traits were checked. Among them, there were 6 QTLs controlling CP, 5 QTLs controlling EE, 20 QTLs controlling CF, 27 QTLs controlling Ash and 15 QTLs controlling Mg, while the value of LOD was greater than 3. When the value of LOD was greater than 5, there were 27 QTLs controlling Ca, 28 QTLs controlling P and 29 QTLs controlling K. The results of the whole genome scaned showed that 481 QTLs for ten agronomic traits were checked.Among them, we checked 74 QTLs for fresh weight, 1 QTL for drought weight, 40 QTLs for natural plant height, 59 QTLs for leaf length, 61 QTLs for leaf width, 34 QTLs for number of the first order tiller, 6 QTLs for maximum length of the branches, 50 QTLs for branch number of main stem and 1 QTL for crown diameter. Meanwhile we detecked 155 QTLs associating with fresh drought ratio. |
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