Natural variation in the sequence of PSY1 and frequency of favorable polymorphisms among tropical and temperate maize germplasm
Natural variation in the sequence of PSY1 and frequency of favorable polymorphisms among tropical and temperate maize germplasm
复制标题
热带和温带玉米种质PSY1序列的自然变异和有利多态性频率
DOI：
10.1007/s00122-012-2026-0
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发表时间：
2013-04-01
影响因子：
5.4
通讯作者：
Yan, Jianbing
中科院分区：
文献类型：
--
作者：
Fu, Zhiyuan;Chai, Yuchao;Yan, Jianbing
维生素A原(Pro-VA)对人类视力和免疫系统健康是必要的，尤其是在成长中的儿童。玉米类胡萝卜素生物合成途径中的第一步是由植烯合成酶1(由PSY1编码)催化的，它控制底物进入该途径的通量。这些底物的流动可以直接用于生产β分支类胡萝卜素(该步骤主要由番茄红素epsilon环化酶基因控制)，但在β-胡萝卜素产生后终止，而不是允许其转化为下一代谢物(该步骤主要由β-类胡萝卜素羟基酶基因控制)。本研究对PSY1在两个不同的玉米群体中进行了关联定位，在一个分离群体中进行了数量性状座位(QTL)的定位，并对PSY1内的位点进行了多态表达分析。结果表明，位于转录起始点上游的378个碱基的Indel和第5个外显子上的SNP导致了Thr到Asn的替换，分别解释了7%和8%的类胡萝卜素变异，这可能是与玉米籽粒中总类胡萝卜素水平相关的功能位点。对PSY1的进化分析有力地表明，在黄玉米与白玉米分化后，这些多态位点发生了正向选择。
Provitamin A (Pro-VA) is necessary for human vision and immune system health, especially in growing children. The first committed step in the maize carotenoid biosynthesis pathway is catalyzed by phytoene synthase 1 (encoded by PSY1) which controls the flux of substrates into the pathway. The flow of these substrates could be directed into production of the β-branch carotenoids (the step controlled largely by the lycopene epsilon cyclase gene), but terminated after the production of β-carotene, rather than allowing it to be converted into the next metabolite (the step controlled largely by the β-carotenoid hydroxylase gene). In this study, PSY1 was subjected to association mapping in two diverse maize populations, quantitative trait loci (QTL) mapping in one segregating population, and expression analysis of lines polymorphic for sites within PSY1. The results indicated that a 378-bp InDel upstream of the transcription start site and a SNP in the fifth exon resulting in a Thr to Asn substitution, explaining 7 and 8 % of the total carotenoid variation, respectively, may be functional sites associated with total carotenoid levels in maize grain. Analysis of the evolution of PSY1 strongly suggests that there was positive selection for these polymorphic sites after the divergence of yellow maize from white maize.