| Stylosanthes is a kind of high grade forage legume which is widely distributed in tropical and subtropical regions of the world. It is the main cultivated forages varieties in southern 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 Fl.202 F2 offspring was gained by F1 self. The morphological characters, agronomic traits and nutrient content changes of this Stylosanthes genetic pedigree were analyzed in order to explore the genetic characteristics of the individual and Inheritance law within the family. The results obtained by ISSR primer and SRAP primer screening lay the foundation for Stylosanthes linkage maps and QTL mapping. The main conclusions of this study are as follows:(1) Stylosanthes guianensis TPRC 1979, dominant Nuclear Male Sterile first discovered in China, were crossed with Stylosanthes guianensis TPRCR273. Pollinating for 2300 flowers,38 seeds were harvested. The hybrid seed setting rate of artificial pollination is about 1.65%.(2) In this study, SRAP molecular markers were analyzed to identify the authenticity of hybrids.223 pair SRAP primers were screened selected to bands specific for the male parent but absent from the female, then 5 pair primers, whose bands pattern clear and stable, were elected and applied to identify the hybrids. A total of 28 progeny, which have male and female features with public zone, were identified are true hybrids.(3) The self-intersection of F1 generation of true hybrids which maleness was absolutely fertile was bagged. and we successfully obtained a cross population populations which included 2 parents and 1 F1 hybrid and 202 F2 segregating population.(4) The analysis of hybrid populations Morphology:The flowers color of F2 generation expressed the segregation ratio of 3:1 through X-square test. The results showed that color of Stylosanthes may be controlled by a pair of main genetic alleles, and yellow flower is the dominant trait to white flower.(5) The fresh weight, dry weight and natural plant height, the main branch number and other six agronomic traits were investigated. The average coefficient of variation of 10 characters was 20.78% that distributed widely ranged from 8.31% to 46.19%. The coefficients of fresh weight and dry weight were the most significant Agronomic traits showed the continuity of normal distribution except for dry weight than fresh weight. Correlation analysis, path analysis, regression analysis and principal component analysis showed significant related among natural plant height, the main branch number, the width of the longest branch, leaf length, leaf width and leaf aspect ratio. There were four characters that had great influence to the yield of the plant, the leaf length, leaf area, branches, and the longest branch.(6) The crude protein, crude fiber and crude fat and other seven quality agronomic traits were investigated. The variation of traits with selecting potential is wide and rich. The average crude protein content of F2 generation was 16.57%, the highest crude was 21.99%, the lowest was 11.67%, the coefficient of variation was 10.83%. The average content of crude fiber content in the F2 generation was 23.53%, and the variation range was 18.31%-31.17%. Quality Traits average coefficient of variation was 18.79%, less than agronomic traits. Normality test showed 10 quality traits take on normal distribution except Ca, P, K and Mg. Correlation analysis showed that the crude protein and crude fat were significantly negatively correlated interplay between them, which provides a theoretical basis for the screening of high-protein low fiber Stylosanthes species.(7) The agronomic traits and the important nutrient content variation of the F2 population were large, and the traits were basically in line with the normal distribution, which was suitable for the mapping population.(8) 100 pairs of candidate primer were chosen to screen the polymorphism between parents.32 primers amplified clear bands. There are three pair of primers by which polymorphism bands were amplified.-The results showed that the ISSR molecular marker is not suitable for the construction of genetic linkage map which based on this hybrid population. Among 702 combinations of primer pair screened,35 combinations could generate consistent polymorphic bands. Polymorphism rate was 5.0%. A total of 267 SRAP marker loci and 153 polymorphic bands were amplified in this study. The percentage of polymorphic bands was 57.3%. The number of SRAP markers is not up to the requirements of mapping Dense Genetic Linkage map of Stylosanthes. SRAP marker can combined with other markers together to lay the foundation for the construction of a genetic linkage map of Stylosanthes. |
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