Quantitative effects of vernalization requirement, day length and temperature on flowering time of oilseed rape

春化需要量、日长和温度是决定油菜开花天数的关键因素。据报道，不同基因型的油菜春化需求差异较大，春化需求程度与耐霜性呈正相关。在典型的西欧生长条件下，冬季油菜品种的春化要求在12月底就能满足——植株从田间转移到温室，在短时间内就能开花。然而，在野外条件下，花期仅在4个月后开始，这表明其他因素，如白天长度和/或温度调节花期。本项目的主要目的是阐明春化需要量与耐寒性、冬季存活期和开花时间之间的关系，以及它们与日照长度和温度的关系。因此，由春型品种Topas （DH4079）和冬型油菜Express杂交而成的双单倍体分离群体将具有以下表型特征：(a)在温室条件下春化需求和开花天数，(b)在霜冻室中培养后确定的耐霜冻性，(c)日照长度和/或温度对完全春化植物开花天数的影响。(d)在田间试验（8月播种）中对冬季存活和开花时间的隔离，以及在春播试验（4月播种）中对开花的倾向。所有表型数据将用于在基于Illumina Infinium Brassica 60K SNP Chip技术的高密度分子标记图谱中绘制相应的QTL。通过QTL分析，可以看出在不同环境条件下获得的耐寒性、冬季成活率和开花日数QTL是否会重合或位置不同。一个互补的高分辨率转录组学分析（MACE；海量分析cDNA末端）将被执行，以确定在早花和晚花以及霜敏感和耐霜基因型中差异表达的基因。从MACE获得的cDNA序列（100bp）和Illumina SNP标记序列将用于确定它们在甘蓝型油菜基因组中的物理位置，并与已定位的QTL进行比较。本项目其他合作伙伴开发的影响甘蓝型油菜开花时间的其他基因SNP标记也将被绘制，并将其位置与本项目在不同环境中检测到的QTL进行比较。

Vernalization requirement, day length, and temperature are key factors that determine days to flowering in oilseed rape (Brassica napus L.). For winter oilseed rape genotypes, considerable differences in vernalization requirement have been reported and a positive correlation between the degree of vernalization requirement and frost tolerance has been discussed in the literature. Under typical western European growing conditions, the vernalization requirement of winter oilseed rape cultivars is met by end of December - plants transferred from the field to the greenhouse flower readily within short time. However, under field conditions flowering begins only about four months later, indicating that other factors like day-length and/or temperature regulate flowering time. The main objective of the present project is the elucidation of the relationships between vernalization requirement and frost tolerance, respectively winter survival, and flowering time in dependence of day-length and temperature. Therefore a segregating doubled haploid population, derived from a cross between spring-type variety Topas (DH4079) and winter-type oilseed rape Express will be phenotypic characterized (a) for its vernalization requirement and days to flowering under greenhouse conditions, (b) for its frost tolerance as determined after incubating plants in a frost chamber, (c) for the effect of day-length and/or temperature on days to flowering of fully vernalized plants, and (d) for its segregation for winter survival and flowering time in field experiments (sown in August) as well as for its tendency to form inflorescences in the year of sowing for spring sown trials (sown in April). All phenotypic data will be used to map corresponding QTL in a high density molecular marker map of this population on the basis of the Illumina Infinium Brassica 60K SNP Chip technology. QTL analysis will show if QTL for frost tolerance, winter survival and days to flowering obtained under different environmental conditions will collocate or differ in their positions. A complementary high resolution transcriptomic analysis (MACE; Massive Analysis of cDNA Ends) will be performed to identify genes that are differentially expressed in contrasting bulks of early vs. late flowering and in frost sensitive vs. frost tolerant genotypes. cDNA Sequences (100bp) obtained from MACE and the Illumina SNP marker sequences will be used to identify their physical position in the Brassica napus genome and to compare their position with mapped QTL. SNP markers developed by other project partners of this priority program for other genes affecting flowering time in Brassica napus will also be mapped and their position will be compared with QTL detected in the different environments in this project.