| The development of construction of rice linkage maps using molecular markers is very rapid. Since from McCouch et al constructed the first rice molecular linkage map in 1988, many maps have been published utilizing all kinds of populations and all types of molecular markers. Most of these marker types were RFLP or mixed types with several kinds of markers. Recently, with the implement and accomplishment of rice genomic sequence project, the reports about constructing rice genetic maps with simple sequence repeats (SSR) marker are more and more. Distorted segregation can be detected with almost any kind of genetic marker, including morphological mutant markers, isozymes, and DNA markers. Segregation distortion is influenced by many factors, for example, mapping population, genetic transmission, gametic and zygotic selection, non-homologous recombination, gene transfer, transposable element and environmental agent et al. F2 population is commonly used, up to the present, regardless self- pollination or cross-pollination, most genetic linkage maps in plant were constructed by F2 populations. F2 populations established easily and didn't take much time, it is the biggest advantage to construct Genetic linkage map. The development of high-density molecular linkage maps provides a chance to survey the whole genome for loci showing distorted segregation. This research make use of SSR markers to draw a genetic linkage map that comprised of 148 SSR markers loci was constructed from a F2 population consisting of 90 lines by choosing japonica variety Nipponbare which had already completed whole rice genomic sequence project and complete chromosome of 4 whole genomic sequence project of indica variety Guangluai-4. This study analyzed and discussed reasons for segregation distortion. The main results are as follows:1. There were three parts primers: One part of 505 primers for SSR analysis on thesechromosome were published by Cornell University, The other part of 7 primers were published by The Rice Genome Sequencing Project of Japanese. And the besides part of 244 primers were designed by our laboratory. A genetic linkage map comprised of 148 markers loci and covers a length of 1737.81 cM, with an average distance of 11.90 cM between adjacent markers.2. Examined polymorphisms of parents by 756 primers, there were 200 primers showed polymorphisms, the ratio of polymorphisms was 26.46%.3. Analyzed the linkage of 158 markers and gained a linkage map comprised of 16linkage populations, the map included of 91 RM loci, 56 RP loci and 1 OSR loci in 148 markings. These markers were mapped 12 chromosomes, respectively.4. This genetic map was highly comparable with the rice genetic map of Temnykh. Most of markers were mapped on the same chromosomes and aligned in the same order. But the map has some shortages, for example, the average distance was longer between adjacent markers and the markers were not lot and so on.5. Analyzed the linkage map of 56 RP markers by bioinformatics, loci of 9 RP markersdifferent from on this map.6. The F2 population showing very significant deviation.49 markers (33.11%) showed the genetic distortion (P<0.05). Of the total segregation distortion markers, 36 markers deviated toward male parent GuangLuAi-4,besides 13 markers distorted to heterozygote, But there was no marker deviated toward female parent japonica Nipponbare. In this research, reasons for segregation distortion may be caused by gametophyte and zygotic. Because most gametophyte loci and sterility loci mapped segregation distortion regions, these results indicated that segregation distortion maybe caused by gametophyte loci and sterility loci. Finally, this study analyzed skewed segregation of unmapped markers.7. 44 markers (89.80%) showed deviation on the map were mapped chromosomes 2,3,4,5,6,7 and 9, respectively. There are a lots of markers were in segregation distortion regions. SDR2-2,SDR2-3,SDR3,SDR4,SDR5,SDR6 and SDR7 were deviated toward guangLuAi-4, SDR2-1 and SDR-9 were deviated toward heterozygote.
|
PDF Full Text Request