Sweet corn (Zea mays L.) is highly consumed in the United States, but does not make major contributions to the daily intake of carotenoids (provitamin A carotenoids, lutein and zeaxanthin) that would help in the prevention of health complications. A genome‐wide association study of seven kernel carotenoids and twelve derivative traits was conducted in a sweet corn inbred line association panel ranging from light to dark yellow in endosperm color to elucidate the genetic basis of carotenoid levels in fresh kernels. In agreement with earlier studies of maize kernels at maturity, we detected an association of β‐carotene hydroxylase (crtRB1) with β‐carotene concentration and lycopene epsilon cyclase (lcyE) with the ratio of flux between the α‐ and β‐carotene branches in the carotenoid biosynthetic pathway. Additionally, we found that 5% or less of the evaluated inbred lines possessing the shrunken2 (sh2) endosperm mutation had the most favorable lycE allele or crtRB1 haplotype for elevating β‐branch carotenoids (β‐carotene and zeaxanthin) or β‐carotene, respectively. Genomic prediction models with genome‐wide markers obtained moderately high predictive abilities for the carotenoid traits, especially lutein, and outperformed models with less markers that targeted candidate genes implicated in the synthesis, retention, and/or genetic control of kernel carotenoids. Taken together, our results constitute an important step toward increasing carotenoids in fresh sweet corn kernels.

中文翻译：

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新鲜玉米粒中类胡萝卜素的自然变异受甜玉米中罕见的变异控制

在美国，甜玉米（Zea mays L.）的消费量很高，但对每天摄入的类胡萝卜素（维生素原A类胡萝卜素，叶黄素和玉米黄质）没有重大贡献，这有助于预防健康并发症。在甜玉米近交系的胚乳颜色范围从浅到深黄的全基因组关联研究中，对七个仁类胡萝卜素和十二个衍生性状进行了研究，以阐明新鲜仁中类胡萝卜素水平的遗传基础。与较早的玉米粒成熟研究一致，我们检测到β-胡萝卜素羟化酶（crtRB1）与β-胡萝卜素浓度和番茄红素ε环化酶（lcyE）相关）与类胡萝卜素生物合成途径中α-和β-胡萝卜素分支之间的通量比。此外，我们发现具有收缩的2（sh2）胚乳突变的评估自交系中，有5％或更少的lycE等位基因或crtRB1最有利分别提升β分支类胡萝卜素（β胡萝卜素和玉米黄质）或β胡萝卜素的单体型。具有全基因组标记的基因组预测模型对类胡萝卜素性状（尤其是叶黄素）具有较高的预测能力，其表现优于具有较少标记的模型，这些标记针对的是涉及类胡萝卜素的合成，保留和/或遗传控制的候选基因。综上所述，我们的结果构成了增加新鲜甜玉米粒中类胡萝卜素含量的重要一步。