油菜种子硫苷含量QTL定位和低硫等位基因的发掘与应用

以中、高硫苷油菜品种‘Sollux’与‘高油605’选系‘Gaoyou’杂交F1产生的DH（doubled haploid）群体（SG，n=282）为材料，在中国和德国4种环境下对其硫苷含量进行QTL定位分析，旨在解析高硫双亲背景下的超亲分离现象，发现新的低硫苷等位基因为育种服务；并在QTL水平上通过分析硫苷含量的上位性和环境互作，揭示硫苷遗传较预期复杂的可能原因。研究结果表明，定位的8个主效QTL加性效应值在22～34 μmol·g-1，纯合并存时可影响硫苷表型44 μmol·g-1，可解释群体内遗传变异的约50%。其中3个主效QTL（GSLqA9|1，GSLqC2和GSLqC9）可能与前人在低硫×高硫分离群体中检测到的属同位点。GSLqA9|2，GSLqA8和GSLqC1是SG群体中新检测到的控制种子硫苷含量的QTL。通过育种手段将低硫等位基因引入目前的双低油菜品种，有望进一步降低其硫苷含量至15 μmol·g-1以下，进一步提高其饼粕饲用价值；另检测到8对上位性QTL，效应值在050～185 μmol·g-1，累计总效应2062 μmol·g-1，约为加性总效应的1/2，可能是造成该性状复杂遗传机理的原因之一；5个QTL的8个连锁标记，其标记基因型和性状表现型的符合率在60%～85%，可作为辅助手段应用于低硫苷育种材料筛选。

QTL mapping for glucosinolate content in seeds and its potential utilization in rapeseed breeding

In the present study， doubled haploid （DH） population developed from a cross between the German cultivar Sollux and the Chinese line Gaoyou was used. Both parents possessed high glucosinolate content， and large variation within population. The glucosinolate content of 282 DH lines were collected for QTL mapping over four environments. The objectives of this study were to investigate the genetic basis of transgressive segregation observed in the population， and to discover new allele for low|glucosinolate|content rapeseed breeding. It was shown that eight QTL with additive effects and eight pairs of loci with additive×additive epistasis were detected， which together accounted for more than 50% of the phenotypic variation. Among them， three（GSLqA9|1， GSLqC2 and GSLqC9）were probably homozygous to the previously identified major QTLs on A9， C2 and C9， while GSLqA9|2， GSLqA8 and GSLqC1were more likely to be new identified loci. These favorable alleles were candidate to decrease the seed glucosinolate content to below 15 μmol·g-1， which would improve the feeding value of rapeseed meal. The sum of epistatic effects from eight pairs of loci accounted for half of total additive effects， which might be the reason for the difficulties to further reduce or totally remove the glucosinolate content in rapeseeds. Eight markers linked to the 5 QTL showed good fitness between marker genotypes and trait phenotypes， and were of great potential for the future breeding.