Quinoa (Chenopodium quinoa Willd.) is an ancient grain crop that is tolerant to abiotic stress and has favorable nutritional properties. Downy mildew is the main disease of quinoa and is caused by infections of the biotrophic oomycete Peronospora variabilis Gaüm. Since the disease causes major yield losses, identifying sources of downy mildew tolerance in genetic resources and understanding its genetic basis are important goals in quinoa breeding. We infected 132 South American genotypes, three Danish cultivars and the weedy relative C. album with a single isolate of P. variabilis under greenhouse conditions and observed a large variation in disease traits like severity of infection, which ranged from 5 to 83%. Linear mixed models revealed a significant effect of genotypes on disease traits with high heritabilities (0.72 to 0.81). Factors like altitude at site of origin or seed saponin content did not correlate with mildew tolerance, but stomatal width was weakly correlated with severity of infection. Despite the strong genotypic effects on mildew tolerance, genome-wide association mapping with 88 genotypes failed to identify significant marker-trait associations indicating a polygenic architecture of mildew tolerance. The strong genetic effects on mildew tolerance allow to identify genetic resources, which are valuable sources of resistance in future quinoa breeding.

中文翻译：

---

藜（Chenopodium quinoa）遗传资源中对霜霉病病原体Peronospora variabilis 耐受性的遗传变异

藜麦 (Chenopodium quinoa Willd.) 是一种古老的谷物作物，可耐受非生物胁迫并具有良好的营养特性。霜霉病是藜麦的主要病害，由生物营养型卵菌 Peronospora variabilis Gaüm 感染引起。由于该病害造成重大产量损失，因此鉴定遗传资源中抗霜霉病的来源并了解其遗传基础是藜麦育种的重要目标。我们在温室条件下感染了 132 个南美基因型、三个丹麦栽培品种和杂草相关的 C.album，并在温室条件下用单一的 P. variabilis 分离株感染了疾病特征，如感染的严重程度，范围从 5% 到 83%。线性混合模型揭示了基因型对具有高遗传力（0.72 至 0.81）的疾病性状的显着影响。原产地海拔或种子皂苷含量等因素与霉菌耐受性无关，但气孔宽度与感染严重程度弱相关。尽管对霉菌耐受性有很强的基因型影响，但对 88 个基因型的全基因组关联作图未能确定显着的标记-性状关联，表明霉菌耐受性的多基因结构。对霉菌耐受性的强烈遗传效应允许鉴定遗传资源，这是未来藜麦育种中宝贵的抗性来源。具有 88 个基因型的全基因组关联作图未能确定显着的标记性状关联，表明抗霉病的多基因结构。对霉菌耐受性的强烈遗传效应允许鉴定遗传资源，这是未来藜麦育种中宝贵的抗性来源。具有 88 个基因型的全基因组关联作图未能确定显着的标记性状关联，表明抗霉病的多基因结构。对霉菌耐受性的强烈遗传效应允许鉴定遗传资源，这是未来藜麦育种中宝贵的抗性来源。