小麦耐低钾性状的全基因组关联分析

  【目的】  筛选与小麦耐低钾性状相关的标记,为揭示小麦耐低钾性状的遗传机理奠定基础。  【方法】  本研究以198份中国黄淮南片麦区的小麦品种 (系) 作为供试群体。小麦种子发芽后,幼苗在正常钾营养液中生长4天,然后在低钾 (0.01 mmol/L) 和正常钾 (2 mmol/L) 营养液中生长25天。调查生物量,分析地上部和根部钾含量,计算小麦7个性状的相对值,利用小麦35K SNP芯片结合Q + K混合线性模型 (mixed linear model,MLM) 对7个耐低钾性状进行全基因组关联 (genome-wide association study,GWAS) 分析,筛选位于显著关联位点上的候选基因并进行功能注释,对显著关联位点进行等位变异分析,发掘优异等位变异。  【结果】  低钾胁迫条件下,地上部、根部、全株钾累积量和钾累积量根冠比显著降低,地上部、根部、全株钾利用指数显著升高。群体结构分析和PCA分析均将供试群体分为2个亚群。通过GWAS分析,共检测到75个显著关联单核苷酸多态性 (single nucleotide polymorphism,SNP) 标记 (P < 0.001),分布在除1A、3B、3D、4D和6A染色体外的16条染色体上。通过候选基因搜寻及注释,共筛选出13个可能与小麦耐低钾胁迫相关的候选基因。等位变异分析共挖掘了 14 个优异等位变异,其中 6 个优异等位变异在供试群体中出现的频率较大。  【结论】  7个耐低钾性状均具有明显的数量性状特征,变异系数范围为20.66%～30.44%。40%的SNP标记分布在2B、5B和6B染色体上,21个SNP位点与多个耐低钾性状显著关联,单个SNP标记解释的表型贡献率的变异范围为5.78%～11.22%。TraesCS4A02G335400、TraesCS2B02G306000、TraesCS5B02G260000可能参与物质转运过程,TraesCS1D02G350600和TraesCSU02G105300可能参与逆境胁迫响应等生理过程,TraesCS2A02G000200可能参与逆境胁迫下的信号转导过程。

Genome-wide association study of traits related to low potassium tolerance in common wheat

  【Objectives】  Screening markers associated with low potassium (K) tolerance in wheat will lay a foundation for revealing the genetic mechanism of low K tolerance in wheat.  【Methods】  Total of 198 wheat cultivars were collected from the wheat planting area in southern of Huang-Huai River plain. After germination of seeds, the wheat seedings were cultured in normal K nutrition solution for 4 days, then transferred into low (0.01 mmol/L) and normal (2 mmol/L) K solution for 25 days. The biomass and K contents of wheat shoots and roots were measured. The values of 7 traits were calculated. The genome-wide association study (GWAS) was analyzed with 35K single nucleotide polymorphism (SNP) chips by mixed linear model (MLM). The candidate genes and superior alleles were screened with associated SNP loci.  【Results】  Of the seven low-K-tolerance traits, the K accumulation of shoot, root and total plant and the K accumulation ratio of root to shoot declined significantly, while the K utilization index of shoot, root and total plant increased significantly under low K stress condition. The population materials were divided into two subgroups based on structure analysis and PCA analysis. GWAS analysis revealed that 75 SNP loci were distributed on 16 chromosomes (P < 0.001), except 1A, 3B, 3D, 4D and 6A chromosomes. There were 13 available candidate genes screened out, which might associate significantly with the seven low-K-tolerance related traits in the regions from the positions of SNP, 14 superior alleles were obtained and 6 superior alleles had higher frequency in the tested population.   【Conclusions】  Seven low-K-tolerance related traits fitted the feature of quantitative character with coefficient variation ranged from 20.66% to 30.44%. 40% of SNP markers distribute on 2B, 5B and 6B chromosomes. 21 SNP loci were associated significantly with more than 2 low-K-tolerance related traits. The phenotypic contribution explained by single marker loci varied from 5.78% to 11.22%. TraesCS4A02G335400, TraesCS2B02G306000 and TraesCS5B02G260000 may be involved in material transportation process; TraesCS1D02G350600 and TraesCSU02G105300 may involved in stress response; TraesCS2A02G000200 may regulate the signal transduction in environmental stress.