Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA.
Dep. of Agronomy, Univ. of Wisconsin-Madison, Madison, WI, 53706, USA.
Plant Genome. 2020 Mar;13(1):e20008. doi: 10.1002/tpg2.20008. Epub 2020 Apr 24.
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.
甜玉米（Zea mays L.）在美国的消费量很高，但它对类胡萝卜素（维生素 A 前体类胡萝卜素、叶黄素和玉米黄质）的日常摄入量贡献不大，而类胡萝卜素有助于预防健康并发症。本研究在一个甜玉米自交系关联群体中进行了一项针对七种籽粒类胡萝卜素和十二种衍生性状的全基因组关联研究，该群体的胚乳颜色从浅黄色到深黄色不等，旨在阐明新鲜籽粒中类胡萝卜素水平的遗传基础。与玉米成熟籽粒的早期研究一致，我们检测到β-胡萝卜素羟化酶（crtRB1）与β-胡萝卜素浓度以及番茄红素 ε 环化酶（lcyE）与类胡萝卜素生物合成途径中α-和β-胡萝卜素分支之间通量比值之间存在关联。此外，我们发现，5%或更少的具有皱缩 2 号（sh2）胚乳突变的自交系具有最有利的 lycE 等位基因或 crtRB1 单倍型，可分别提高β-支链类胡萝卜素（β-胡萝卜素和玉米黄质）或β-胡萝卜素。使用全基因组标记获得的基因组预测模型对类胡萝卜素性状具有较高的预测能力，尤其是叶黄素，并且优于针对参与合成、保留和/或遗传控制籽粒类胡萝卜素的候选基因的较少标记的模型。总之，我们的研究结果是提高新鲜甜玉米籽粒类胡萝卜素含量的重要一步。
