| Chinese cabbage (Brassica rapa, L. syn. Brassica campestris) belongs to Brassica genus, with high nutritional value and is one of the most important vegetable crops in China. Complex genetic background and extensive variation of this crop make it difficult to improve some important agronomic traits. Consumers are having higher requirement and paying much attention to the quality of vegetable nutrition with the improvement of standard of living. Degradation products of glucosinolates constitute the primary source of special spicy flavors in cruciferous vegetables, and also been taken as natural insect resistance and antibacterial agent and be relevant with insect propagation and prediction; Many studies show that isothiocyanate has good anticancer effect and indirect antioxidant effect. The relative researches on glucosinolates are attaching much more importance as the main active ingredient of Brassica rapa. So genetic analysi of nutritional quality traits in B. rapa at molecular levels will achieve the purpose of the improvement of nutrition quality and beneficial types of glucosinolates, and exploitation and utilization to key genes in B. rapa.This study used BC2DH population developed by crossing of European oiled cabbage Rapid Cycling L144 and Chinese cabbage Z16 as parents, which were diversed in glucosinolate content, morphological traits and growth period comprising of 120 lines. Evaluaion to glucosinolate composition and content in B. rapa. leaves was conducted by HPLC, which would be useful to exploit glucosinolate accumulation and genetics in B. rapa.. Genetic linkage map of B. rapa. wasconstructed on this BC2DH population, and quantitative locus (QTL) analysis was performed for glucosinolate content. Main conclusions are listed as follows:1. Eight main glucosinolates were determined by HPLC among 13 Brassica rapa types, and aliphatic glucosinolates were the major glucosinolates, taken the ratio of above 64%; While in Chinese cabbage, indolic glucosinolates taken the highest ratio relatively about 28.5%.The total glucosinolate content of wild cabbage was the highest among all 13 different types, about 17.3μmol·g-1 DW. Gluconapin (NAP) content was at most and with the widest variation, varied from 0 to 53.87μmol·g-1 DW, and the mean content was 2.68μmol·g-1 DW. Analysis of variance indicated, for aliphatic glucosinolates, there was a significant difference between different varieties and for aromatic glucosinolates also significantly different between different seasons. Aliphatic glucosinolate NAP showed negatively correlation with PRO, and positively correlation with GBN; Aromatic glucosinolate NAS was significantly positive correlative with aliphatic glucosinolate GBN by correlation analysis. Six materials with high glucosinolate content were selected in Chinese cabbage by principal component analysis, numbered 19,32,41,45,46 and 47.2. Genetic linkage maps were constructed based on BC2DH population developed by crossing an European oiled cabbage Rapid Cycling (L144) and a Chinese cabbage variety Z16. One hundred and ninety four markers were developed to construct a 10 linkage groups genetic map covering a total distance of 563.3 cM. The average interval distance was 2.90 cM.3. Interval mapping and multiple-QTL model mapping (MQM) methods were employed in mapping and analysis of QTL controlling glucosinolate contents.15 putative QTL controlling glucosinolate,2 for NAP,3 for GBN,3 for PRO,2 for GBC,1 for NEO,2 for 4OH,2 for NAS,3 for aliphatic glucosinolates content,1 for total glucosinolate and 1 for GBN/Ali were detected in 8 linkage groups. The LOD value was from 3.20 to 16.76, and the percentages of variation explained were varied from 12.5% to 77.0%. |
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