Genetic Dissecton Of Glucosinolates And Some Metabolites In Brassica Rapa

Brassica rapa (syn. campestris) is an important species of the Brassica genus, which includes a varietyof vegetable and oilseed crops. Complex genetic basis of this crop make it difficult to improve someimportant agronomic traits. On the other hand, lots of cultivar groups and abundant genetic diversitywere formed due to long cultivation history, which provide expansive materials for improving someimportant agronomic traits. Recently quality breeding was attached importance with the improvement ofstandard of living, but many qulity traits such as glucosinolate lacked systematic researches inheritability. So genetic analysi of nutritional quality traits in B. rapa at metabolites and molecular levelswill provide a genetic bases for the improvement of quality, and this also will be used for exploitationand utilization to key genes in B. rapa.In the present study, we established technology systems of metabolites analysis by use of GC-MS inchinese cabbage according to the results of Arabidopsis and potato, and identification and geneticdissection of some matabolites were carried. And we described natural variation for glucosinolatescontents detected with HPLC method in B. rapa plant. It would be useful to exploit glucosinolateaccumulation and genetics in B. rapa. Based on the selection of optimal parents, genetic researchsegeragation populations with abundant information were constructed and genetic linkage maps of B.rapa were developed. Furthermore, quantitative trait loci (QTL) analysis of glucosinolate traits has beenperformed. Main conclusions are listed as follows:1. 8 individual glucosinolate wre determined by HPLC, natural variation has been shown to bepresent in accessions of B. rapa for glucosinolate contents in plants. Maximum variation inglucosinolate(NAP) levels in diffrent accessions was 1127 times, the variation range of otherglucosinolates in diffrent accessions were 18-152 times, the variation of total glucosinolates indiffrent accessions were 51 times. And the variation level was different among or within differentcultivar groups. Furthermore, the diversity analysis of AOP₂ gene in B.rapa which are key genes inglucosinolate biosynthesis pathways was performed.2. Genetic linkage maps was constructed based on BILs population developed by crossing a Rapidcycling L144 and a flowering Chinese cabbage variety L58. 156 markers were organized into 17main linkage groups covering a total distance of 719.2cM. The average interval distance was 4.6cM. Length of linkage groups varied from 11.7 cM to 88.7 cM and the number of markers to eachgroup ranged from 3 to 25.3. Interval mapping and multiple-QTL model mapping (MQM) methods were employed in mappingand analysis of QTL controlling glucosinolate contents. 14 putative QTL were detected in 6 linkagegroups, including 3 for NAP, 3 for PRO, 1 for GBN, 2 for total glucosinolate, 1 for NAP/Tali, 2for 4ME, 1 for NAS. The percentages of variation explained wre varied between 16.0-82.7%.4. Analysis protocol of chinese cabbage by GC-MS was optimized and confirmed, GC-MS analyticalparameters were confirmed at the same time. Based on this protocols, 47 compound profiles within chinese cabbage were detected by GC-MS and divided them into six classes, they are organic acids,sugars, sugar alcohols, amino acids, indicans and aromatic amine. In those compounds spectra, atotal of 33 QTL were deteced in 20 peaks out of 33 on 9 linkage groups, which individuallyexplained between 6.7% and 92.1% of the additive genetic variation.