Construction Of SSR Fingerprinting Maps For High Oil Content Brassica Napus Cultivars And Selection Of Markers For Oil Content

Rapeseed is one of the most important oilseed crops in China and the world. Germplasm resources play an important role in life sciences and agriculture sciences. Because the seed marketing and management have not fully established for patentee and farmers'benefit, it is a great significance to set up identification method for the protection of rapeseed cultivars.Oil content is a major quality character agricultural value with great heritability. The increase of 1% of oil content equals to 2-2.5% increase of seed yield. Oil content is difficult to improve and identify because it is a quantitative trait and influenced by the environment. Molecular breeding using markers linked to oil content is becoming one of the main methods to improve the seed quality.DNA marker systems include RAPD,RFLP,SSR,AFLP and SRAP. These markers have characteristic respectively and an ideal DNA marker system should be genetically polymorphic, co-dominant, full information, even marker contribution in genome, widely exited in genome, stable, highly efficient to be discriminated, easy to be tested and cheap in primer development and operation. SSR marker possesses all the above advantages mentioned and have been adopted for DNA fingerprinting and identification of linkage markers. EST marker is a novel type of molecular tool with remarkable advantages, such as ease development, more informative, and highly transferable, especially for preferential targeting ORFs. EST markers are widely used in plants genetics and breeding, such as construction of genetic linkage maps, important trait gene tagging location, comparative mapping, genetic diversity, cultivar identification and marker-assisted selection.This thesis is composed of two parts:1) Construction of SSR fingerprinting maps for three high oil content Brassica napus cultivars. The results supply legal and scientific supports for cultivars registration, intellectual property protection and DUS(Distinctness,Uniformity,Stability)testing of cultivars. 2) The construction of a oil content segregation population and identification of the linkage markers with oil content. They are prerequisites to the MAS study.1 Construction of SSR fingerprinting maps for three high oil content Brassica napus cultivars.1) Fourty-one polymorphic fragments were amplified by nine SSR primers; Primer P084 amplified seven polymorphic fragments which is the most in all primers and primer P029 amplified two polymorphic fragments which is the least; The percentage of polymorphic fragments was 95% and the number of polymorphic fragments per primer combination was 4.56.2) Nine SSR primers constructed the fingerprinting maps of three high oil content Brassica napus cultivars and distinguished them from other 138 contrasted cultivars.3) The cluster analysis showed that all tested-cultivars can be identified at 1.00 similarty index level, and different strains of the same cultivars have the closest genetic distance.; The individual plants from the same cultivar also showed tiny difference on DNA level.4) In this study, the three high oil content cultivars fingerprints was constructed with nine primer combinations. In the fingerprints, combination of nine SSR primers produced fourty-one polymorphic bands and the probability for cultivars have the same fingerprints was only (1/2)41.2. The construction of a oil content segregation population and identification of the linkage markers with oil content. 1) F2 populations were produced from cross between Zhongyou 036 and 51070 at two locations-Wuhan and Xiangfan. The population sizes are 211 plants and 280 plants respectively. The results of oil content detection showed that two F2 populations can be used for oil content study. But oil content of the parents and F2 plants are lower in Xiangfan than in Wuhan. This result showed that the interaction between oil content and environment are evident. Geographical position, field management and different weather all have effects on the oil content.2) A total of 44 polymorphic primers were screened from 200 SSR primers and 40 EST primers. The percentage of polymorphic primers was 24%. The 44 polymorphic primers include 35 SSR primers and nine EST primers. About 17 amplified fragments were revealed by nine SSR primers in Wuhan population, include eight SSR markers and nine EST markers. The number of polymorphic fragments per primer combination is 1.9. Two primers exist partial separation. 3) Correlation analysis between markers and oil content showed that marker OC2-1 linked to oil content at a significant level of 0.001.