甘蓝型油菜角果长度性状的全基因组关联分析

角果长度是油菜重要的农艺性状,适度增加角果长度有利于扩大角果库容量,增加光合面积,提高油菜的籽粒产量。本研究利用Illumina60KSNP芯片对496份具有代表性的油菜资源进行基因型分析,考察群体在4个环境中的角果长度表型,利用MLM和GLM模型进行全基因组关联分析。结果表明, MLM模型检测到7个位点,联合解释25.01%的表型变异; GLM模型检测到25个位点,联合解释41.77%的表型变异。合并共同位点后得到27个位点,其中7个与前人报道的QTL重叠,其余20个是新鉴定的位点。效应最大的位点Bn-A09-p29991443位于A09染色体,在MLM和GLM模型中分别解释13.89%和12.86%的表型变异,携带其优异等位基因的材料平均角果长度增加0.89cm。同时,在该位点附近找到已克隆的油菜角果长度基因ARF18和BnaA9.CYP78A9。此外,在5个位点附近发现拟南芥已知角果长度基因GID1b、FUL、EOD3、DOF4.4和GA20ox1的同源拷贝。本研究结果有助于解析角果长度的遗传基础,为研究角果长度的调控机理,指导角果长度的遗传改良打下基础。

Genome-wide association study of silique length in rapeseed (Brassica napus L.)

Silique length is a key agronomic trait of rapeseed. Moderately increasing silique length is conducive to high seed yield by enlarging photosynthetic area and seed volume. A collection of 496 representative rapeseed accessions was genotyped by the Illumina 60K SNP array, and phenotyped for silique length in four environments. The genome-wide association study (GWAS) of silique length was performed via the MLM (Mixed linear model) and GLM (General linear model). Seven loci and 25 loci were detected with MLM and GLM, which explained 25.01% and 41.77% of the phenotypic variance, respectively. Combining the common loci between two models, we finally got 27 unique loci, of which seven were overlapped with reported QTLs, and 20 were new one. Bn-A09-p29991443, the most effective locus, was located on chromosome A09, accounting for 13.89% and 12.86% of the phenotypic variance in MLM and GLM, respectively. Silique length of accessions with the favorable allele of Bn-A09-p29991443 was averagely 0.89 cm longer than that with the unfavorable allele. The cloned silique length genes ARF18 and BnaA9.CYP78A9 in rapeseed was found to be colocalized with Bn-A09-p29991443. Besides, five candidates including GID1b, FUL, EOD3, DOF4.4 and GA20ox1, orthologous to documented Arabidopsis silique length genes, were found near our GWAS loci. The results provide an insight into the genetic basis of silique length and lay a foundation for further mechanism exploration and breeding for this trait in B. napus.