Costruction of a Linkage Map and Analysis on Genetics Recombination of an F2 population in Rice Using SSR Markers
| Autor: | Ya-Ling Chu, 朱雅玲 |
|---|---|
| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 A molecular linkage map of rice was constructed using 93 individuals of an F2 population from a cross between cultivars Taichung-Sen 10 and Koshihikari. It consists of 102 SSR (simple sequence repeat) DNA markers distributed in 12 linkage groups, totally spanning 1338 cM with an average interval spacing 15.04 cM. This is the first complete map of rice in Taiwan, and it is a powerful tool for marker-assisted breeding and genetic studies especially for the genetic recombination in individuals of a segregating population. The F2 population is a crucial generation for genetic studies and determining strategies on selection. Since the SSR markers have codominant inheritance and demand little DNA for PCR analysis, it makes study genetic recombination of individual F2 plants become possible. According the genotypic frequencies of SSR markers, segregation distortion was found in the F2 population. About 46.08 % of investigated markers, 47 out of 102, segregated distortedly from Medelian ratios (1:2:1 or 3:1). Distortion segregation is often found in the loci of the chromosome 6, and seldom found in the chromosomes 7, 9, and 10. Besides, the events of distortion segregation were generally happened at the ends of the chromosomes 1, 5, 8, and 11. Compared to male parent with japonica type, female parent with indica type contributed more genetic materials in the chromosomes 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, and 12, to the F2 progenies, but less in the chromosome 7. Approximately equal contribution from both parents was found in the chromosome 10 of the F2 progenies. The frequency of single crossing over (SCO) was ranged from 0.97 to 2.26 times per pair of chromosomes. However, the SCO occurred frequently 16-20 times and followed by 12-16 times for an F2 individual. The averaged times of double crossing over (DCO) for each chromosome was ranged from 0.22 (chromosome 7) to 0.94 (chromosome 2). Deviation of observed homozygosity to the expected ratio (50%) was found in the chromosomes 1, 3, 4, 7, and 8. Most homozygous loci were derived from parent with indica type except for loci at the ends of the chromosomes 1 and 11 contributed from parent with japonica type. More expected proportions of heterozygotes were found in the chromosome 6. There was one allele segregating in the F2 population but not detected in both parents and F1. And 13 SSR markers originally designed as codominant inheritance were detected with dominant type and were mapped on expected regions. These evidences have revealed the genetic variations at the repeat sequences or the flanking sequences. The results of this study not only provide a tool for genetic analysis and rice breeding, but also contribute valuable information for breeding practices. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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