小麦茎部镉积累性状全基因组关联分析及优异位点挖掘

Whole Genome Association Analysis and Identification of Excellent Loci for Cadmium Accumulation Traits in Wheat(Triticum aestivum)Stems

小麦镉(Cd)污染日益加重,严重威胁食品安全和人类健康,培育和应用低镉积累品种是降低镉污染小麦风险的最有效途径之一,通过分子标记辅助手段可加快低镉积累特性小麦的筛选和培育。本研究选用175份小麦种质材料,种植于陕西省镉中度污染农田,对灌浆初期小麦茎部镉含量、镉富集系数和转运系数进行聚类分析,筛选出10个低镉积累特性种质。同时利用小麦660K单核苷酸多态性(SNP)芯片,通过3种模型对茎部镉含量、生物富集系数和转运系数进行全基因组关联分析,共鉴定到33个相关遗传位点,其中28个是新的SNP位点。针对茎部镉含量和转运系数3A上的2个主效QTL,开发了KASP标记,并在验证群体中明确了其准确性和实用性。基于基因注释和同源基因比对,预测了10个基因可能直接参与小麦镉积累转运相关生物过程;其中TraesCS3A02G289200基因是一个热休克转录因子,它在水稻中的同源基因(OsHsfA4a)被验证能够提高水稻对镉的耐受性。10个低镉积累特性种质及相关基因可用于小麦耐镉污染育种及有效分子标记开发。

Cadmium(Cd)pollution in wheat is becoming increasingly serious,posing a significant threat to food safety and human health.Breeding and using wheat varieties with low cadmium accumulation are one of the most effective ways to reduce the risk of cadmium pollution in wheat.Molecular marker-assisted selection can accelerate the screening and breeding of wheat varieties with low cadmium accumulation characteristics.In this study,a total of 175 wheat germplasms were cultivated in moderately cadmium-polluted farmland located in Shaanxi Province.Cluster analysis was performed on the cadmium content,enrichment factor,and transfer factor of wheat stems during the grain filling stage.Subsequently,ten germplasms with favorable low cadmium accumulation traits were selected.The wheat 660K single nucleotide polymorphism(SNP)array was employed to conduct a genome-wide association analysis on the stem cadmium content,biological enrichment factor,and transfer factor using three different models.A total of 33 relevant genetic loci were identified,of which 28 were novel SNP loci.KASP markers were designed for two major effect QTLs relative to stem cadmium content and transfer factor on 3A,and their precision and practicality were duly validated in a representative population.By gene annotation and homologous gene alignment,it was inferred that 10 genes could plausibly participate in the biological mechanisms associated with cadmium uptake and transport in wheat.Notably,the gene TraesCS3A02G289200 was identified as a heat shock transcription factor,with its homologous gene(OsHsfA4a)in rice having been demonstrated to enhance the plant's cadmium tolerance.The ten germplasm resources with low cadmium accumulation relevant gene can he used to breed wheat varieties with high cadmium tolerance,and exploit effective molecular markers.