| Rapeseed is an important economic crops in the world and the most largest oil crops in China. As an edible vegetable oil with high-quality, rapeseed oil is rich in fatty acids, improving the fatty acid content in rapeseed quality breeding is thus helpful to balance the composition of fatty acids and increase the nutritional value of rapeseed.Fatty acids in rapeseed are quantitative quality traits with complex genetic bases, which are simultaneously controlled by genetic effects from different genetic systems including embryo and/or maternal nuclear genomes. Moreover, the traits can be controlled both by genetic main effects and gene×environment interaction effect. Hence, taking all of the influnce of embryo, maternal plant and the environment into account during quantitative trait locus (QTL) mapping, understanding the distribution of QTLs located both on embryo and maternal nuclear genomes, and dissecting the total genetic effect into various genetic main effects and genotype×environment interaction effect components could in-depth reveal the complex genetic nature of rapeseed fatty acids, which could provide some scientific basis to further theoretical studies and molecular marker-assisted breeding in the future.In present study, a new developed mapping model and related mapping software which could analyze the embryo and maternal main effects as well as their QTL×environment (QE) interaction effects on QTLs, and two-way backcross mapping populations were used to detect the QTLs both located in the amphidiploid embryo and maternal plant genomes and study the QTL distribution, genetic effect and correlations among traits across different environments based on different genetic systems for fatty acid contents in rapeseed. The main study results are as follows:1) A total of27QTLs for oleic, linoleic, palmitic, linolenic and eicosenoic acid contents which simultaneously located in the embryo and maternal plant genomes were subsequently identified. Amongest, qLAC-6-1, qLAC-13-4, qLAC-19-6, qPAC-6-1, qPAC-9-3, qPAC-15-5, qPAC-17-6, qPAC-18-7, qPAC-19-8, qLIAC-15-7, qEIAC-9-2and qEIAC-13-3were the new found QTLs for rapeseed fatty acids.2) Three QTLs for oleic acid content were found on chromosomes A3, A8and C3, which were qOAC-3-1, qOAC-8-2and qOAC-13-3, respectively, and could explain84.33%of the phenotypic variation altogether. All the three QTL were major QTLs respectively explained46.42%,25.42%and12.49%of the phenotypic variation, and all of them had significant embryo and maternal additive main effects as well as embryo dominance main effect. Amongest,1QTL (qOAC-8-2) also detected significant embryo dominance interation effect.3) Six QTLs were detected for linoleic acid content, and could explain82.96%of the phenotypic variation in all, which were qLAC-6-1, qLAC-8-2, qLAC-11-3, qLAC-13-4, qLAC-13-5and qLAC-19-6and respectively distributed over chromosomes A6, A8, C1, C3and C9. Among these QTLs, only qLAC-8-2and qLAC-13-4were major QTLs and each was responsible for30.66%and27.85%of the phenotypic variation. All of the QTLs had significant embryo and maternal additive main effects,3QTLs(qLAC-8-2, qLAC-13-4and qLAC-13-5) also had obvious embryo dominance main effect,1QTL (qLAC-13-5) also had significant embryo and maternal additive interaction effects, and1QTL(qLAC-19-6) was detected with significant embryo dominance interaction effect, too.4) For palmitic acid content,8QTLs including qPAC-6-1, qPAC-8-2, qPAC-9-3, qPAC-13-4, qPAC-15-5, qPAC-17-6, qPAC-18-7and qPAC-19-8were respectively mapped on chromosomes A6, A8, A9, C3, C5, C7, C8and C9, which could totally explain82.93%of the phenotypic variation. Among them, qPAC-8-2, qPAC-18-7and qPAC-19-8were major QTLs, and could respectively explain10.28%,41.56%and12.08%of the phenotypic variation. All of the QTLs had significant embryo and maternal additive main effects, and2QTLs(qPAC-8-2and qPAC-13-4) also had very significant embryo dominance main effect, but no significant QE interaction effect was found in this study.5) Seven QTLs were identified affecting linolenic acid content and respectively resided on chromosomes Al, A4, A6, A8, C3and C5, which were qLIAC-1-1, qLlAC-4-2, qLIAC-6-3, qLIAC-6-4, qLIAC-8-5, qLIAC-13-6and qLIAC-15-7, and totally explained50.79%of the phenotypic variation. Among them, qLIAC-1-1and qLIAC-15-7were the major QTLs for the performance of linolenic acid, and each could explain31.16%and10.06%of the phenotypic variation. All the QTLs had significant embryo and maternal additive main effects, but no significant embryo dominance main effect and QE interaction effect were discovered.6) Three QTLs controlling eicosenoic acid content were identified on chromosomes A8, A9and C3, which contributed to72.32%of phenotypic variation in total and respectively named as qEIAC-8-1, qEIAC-9-2and qEIAC-13-3. The putative qEIAC-8-1 and qEIAC-9-2respectively taking charge of52.80%and14.03%of phenotypic variation were the major QTLs for eicosenoic acid. All of the QTLs had significant embryo and maternal additive main effects as well as notable embryo dominance main effect, but no significant QE interaction effect were found.7) One co-localization in the maker interval of HBr015/JICB0018associated with oleic, linoleic, palmitic, linolenic and eicosenoic acid contents were detected on chromosome A8, and each of the5QTL was nearest to maker HBr015. On chromosome C3, one co-localization including4QTLs for oleic, linoleic, palmitic and linolenic acid contents was in the interval of O113C12/HS-Au8and respectively nearest to maker JICB0633. Two QTLs for palmitic and linoleic acid contents were co-located in the interval of CB10064/HR-Tp3-360on chromosome C9. The qPAC-6-1and qLIAC-6-4mapped on A6, as well as the qPAC-15-5and qLIAC-15-7located on C5were closely linked with each other.8) There were notable positive correlations between C16:0and C18:1, C16:0and C18:2, as well as C18.1and C18:2. C18:3was negatively correlated with C18:1, but C18:3was respectively and positively correlated with C16:0and C18:2. C20:1was negatively correlated with C16:0, C18:1or C18:2, while there was no significant relationship between C20:1and C18:3in the present experiment. |
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