Molecular mapping of QTL and candidate genes governing phytosterol content in winter oilseed rape (Brassica napus) and Indian mustard (Brassica juncea)

植物甾醇，又称植物甾醇，由一组植物甾体化合物组成。它们之所以引起人们的兴趣，是因为它们在植物生长发育中起着至关重要的作用，而且作为人类饮食的一部分，它们以具有降低血液胆固醇的作用而闻名。油料作物种子中存在较高的植物甾醇含量，其相关性至今尚不清楚。与拟南芥相比，我们对芸苔属植物中控制植物甾醇含量的基因一无所知。在之前的工作中，一个很大的基因。德国油菜（Brassica napus）品种间植物甾醇含量存在差异。到目前为止，还没有关于印度芥菜中总甾醇含量或单个成分的资料。甘蓝型油菜和芥菜双倍体的适宜分离群体已经开发出来，并将用于本项目中单个和总种子植物甾醇含量以及其他种子品质性状的QTL定位。拟南芥植物甾醇生物合成途径中已知序列的关键候选基因将从其祖先种油菜、黑油菜和甘蓝中进行测序，以开发位点特异性PCR引物。这些位点特异性引物将用于对两二倍体油菜和芥菜的相关等位基因进行测序。两倍单倍体群体亲本之间的等位基因序列差异将用于候选基因的定位。结果将揭示候选基因的位置是否与植物甾醇含量QTL的位置重叠，以及植物甾醇含量的遗传变异是否与其他种子品质性状的变异有关。

Plant sterols, also called phytosterols, comprise a group of plant steroidal compounds. They are of interest because they play a crucial role in plant growth and development and as part of the human diet they are known for their blood cholesterol-lowering effects. High phytosterol contents occur in seeds of oilseed crops, the relevance of which remains hitherto unknown. In contrast to Arabidopsis nothing is know about the genes governing phytosterol content in Brassica species. In previous work, a large genetic. variation for phytosterol content has been found among German winter oilseed rape (Brassica napus) cultivars. So far no information is available on total phytosterol contents or individual components in Indian mustard B. juncea. Suitable segregating doubled haploid populations of B. napus, and of B. juncea have already been developed and will be used in the present project to map QTL for individual and total seed phytosterol content as well as for other seed quality traits. Key candidate genes of the phytosterol biosynthetic pathway with known sequences from Arabidopsis will be sequenced from the progenitor species Brassica rapa, Brassica nigra and Brassica oleracea to develop locus specific PCR primers. Those locus specific primers will be used to sequence the pertinent alleles in the respective amphidiploid species B. napus and B. juncea. Allelic sequence differences between the parents of the doubled haploid populations will be used to map the candidate genes. Results will reveal if positions of candidate genes overlap with those of QTL for phytosterol content and if genetic variation in phytosterol content is related to variation in other seed quality traits.