QTL Mapping And Analyisis Of A Heavy Panicle Type Rice’s Ear Traits

Rice is one of the most important crops in the world, and is also the model plant of monocotyledons for growth and development of plant, genetic information, genomics research and so on. That gene mapping and cloning of important genes in rice, have always been concerned as one of the important aspects for genetic research and breeding sector.High yield is the most important goal in rice breeding. Yield traits of rice are rather complex, and affected by many factors. For instance, panicles per plant, grain weight,seed-setting rate and number of spikelets per panicle are four main factors affected yield. Besides, related traits of panicle play an important role in yield structure. Therefore, QTL mapping and analysis of rice panicle traits help to clarify development of target trait and formation mechanism of that form molecular level. Furthermore, QTL mapping is also rather important to gene pyramiding breeding, and further improve rice yield.In this study, gene mapping population was developed from a cross between heavy panicle materials Qianlidao and japonica rice Nipponbare for investigation and analysis of the target agronomic traits of parents, and QTL mapping involved in related traits using composition interval mapping. Preliminary results are as followe:1 Parents (NIP and Qianlidao) occurred in significant difference involved in leaf width,spike length, grain number, primary branch, secondary branch, grain density, weight per ear and so on.Six related traits showed continuous number variation and almost continuous distribution in F2 population. Therefore, they are typical quantitative genetic characteristics, and can stduy subsequent genetic analysis corresponding to quantitative traits.Correlation analysis showed there were significant positive correlation in leaf width, panicle number, primary branch, secondary branch, and grain density, one another.2 A rice genetic linkage map comprising 92 SSR and 44 Indel markers loci was constructed using an F2 population consisting of 82 lines from a sub-specific cross between Nipponbare (japonica variety) and Qianlidao (indica variety). The rice genetic likage map covers genome length 1536.5 cM, and the distance is 11.4 cM between each marker, which reached basically requirements of linkage map. It can be used for QTL primary mapping, while this map is not high saturation.3 F2 population was significantly distorted. Among of these markers,116 markers showed segregation distortion (85.29%), of which 79 markers extreme segregation distortion (68.10%).Segregation distortion caused by the choice of the zygote has 20, gamete select caused 93, RM3484,RM3702, os7-38.4 is neither caused by a homozygous select or gametes Select. Segregation distortion rate for Indel markers (97.72%) were significantly higher than that of SSR markers (79.34%). All marks deviated preference to paternal Qianlidao, The causes of segregation distortion were discussed based on our results and previous report.4 According to molecular genetic linkage map constructed, this study carried out QTL detected and effect analysis of related gene to six related traits using Window QTL Cartographer (2.0) software.The results detected 20 QTL sites located chromosome 1,2,3,5,7,8,9and 10 respectively, and the contribution rate of individual QTL was 3%-18%, LOD values ranged from 2.55 to 6.13. Besides, there were 13 location about the effect values being greater than 10%, and 3 of them were less than 5%.We tested the target traits QTLs based on the same detection method, using molecular linkage map which removed 20 significant segregation markers distributed 12 chromosomes. Besides, we also tested target traits QTL using molecular linkage map removed the whole markers of significant segregation.The results removed party markers were the same as that of containing the whole markers, such as QTL number, location and effect and so on. However, segment W76-W77 located on the sixth chromosome found additional QTL with controlled spike length.The result removed the whole markers of significant segregation occurred in significant deviations for QTL number, location and effect, for instance, rather higher effect values Gn7 and Sd7 were detected in three times analyzed.