Comparative Mapping Between Two Populations And Genetic Analysis Of Oil Content With Conditional Approach In Brassica Napus L.

The main purpose of harvesting Brassica napus is to press oil from its rapeseed. so increasing oil content of unit area is the primary research objective of rape breeders. Oil content is a quantitative trait controlled by multiple genes. There are many reports about mapping QTLs of oil conternt, however, the QTLs expressed stabled in multiple environments and populations are rare. The main agronomic characters, such as plant height, fatty acid, flowering time and thousand seed weight had been reported by predecessors, however, the genetic correlation at the level of QTL/gene between these traits and oil content has not been well known.A doubled haploid (DH) population of282lines was derived from the cross between "Sollux" and "Gaoyou", and the phenotypic data of oil content and main fatty acid content determined in four environments were used to map QTL for fatty acids and oil content by unconditional QTL mapping and conditional QTL mapping methods, respectively. Our aim is to analyze the genetic relationship between fatty acid and oil content without major eruic acid allele genes. In this study, another DH population was also constructed by crossing "SGDH-14×Express617",which used to construct an SGE genetic linkage group using two kinds of functional molecular markers. Base on the map, QTL mapping was conducted for nine major agronomic traits by using two-year phenotypic data. Finally, by comparing SGE linkage map with SG map as well as results of QTL mapping respectively, we can confirm the repeated QTLs identified in both maps. The results were as follows:1. A genetic linkage map. spanning1142.8cM with an average interval of6.68cM was constructed.2. The linear comparison between linkage map of SGE and linkage map of SG showed good colinearity in spite of a few intersections, and93sites were completely matched,19sites were partially matched, the ratio of collinear markers is83.6%.3. Unconditional mapping identified7.2.6.4.4,4,7,5and6addictive QTLs for oil content (Oil), erucic acid (C22:1). glucosinolate (GLS), days to flower (FD). height (H). thousand seed weight (SW), length of per pod (SL), density of per pod (SD) and seeds of per pod (SS) respectively; while, there are2,3,4,2,2,1,2and4paired epistasic QTLs for Oil, GLS, SW, H, SL, SS and FD respectively.4. There are1,1,1,2,2and4common QTLs for Oil, SW, GLS, H and FD respectively detected in both populations.5. Unconditional mapping identified seven QTLs for erucic acid, and four of them were newly detected on linkage group A2, A7, A9and C1respectively, and identified ten QTLs for oleic acid, the one on linkage group C7was novel QTL. Ten QTLs were also found for linoleic acid, five of them were newly detected on linkage group A3、A4、A10、C6、C7and C9respectively. In addition, five QTLs were also identified for linoleinc acid, and the one on group A9was newly detected.6. Conditional QTL mapping showed that three QTLs (OilA9, OilC2and OilC8-2) were greatly influenced by linoleic acid; a minor gene controlling the oil content may exist in the regions of OilAl, OilA7and OilC8-2. Furthermore. OilA4was found to be influenced by oleic acid, linoleinc acid and erucic acid simultaneously. Four new conditional QTLs were also detected, showing the complexity and uncontrollability of oil content...