Data from: Defining the role of the MADS-box gene, Zea agamous like1, a target of selection during maize domestication

Genomic scans for genes that show the signature of past selection have been widely applied to a number of species and have identified a large number of selection candidate genes. In cultivated maize (Zea mays ssp. mays) selection scans have identified several hundred candidate domestication genes by comparing nucleotide diversity and differentiation between maize and its progenitor, teosinte (Z. mays ssp. parviglumis). One of these is a gene called zea agamous-like1 (zagl1), a MADS-box transcription factor, that is known for its function in the control of flowering time. To determine the trait(s) controlled by zagl1 that was (were) the target(s) of selection during maize domestication, we created a set of recombinant chromosome isogenic lines that differ for the maize versus teosinte alleles of zagl1 and which carry cross-overs between zagl1 and its neighbor genes. These lines were grown in a randomized trial and scored for flowering time and domestication related traits. The results indicated that the maize versus teosinte alleles of zagl1 affect flowering time as expected, as well as multiple traits related to ear size with the maize allele conferring larger ears with more kernels. Our results suggest that zagl1 may have been under selection during domestication to increase the size of the maize ear.

针对携带既往选择特征信号的基因所开展的基因组扫描（genomic scan），已在众多物种中得到广泛应用，并已鉴定出大量选择候选基因。在栽培玉米（Zea mays ssp. mays）中，研究人员通过比较栽培玉米与其祖先大刍草（Z. mays ssp. parviglumis）之间的核苷酸多样性与遗传分化，借助选择扫描技术鉴定出数百个候选驯化基因。其中一个基因为Zea agamous-like1（zagl1），属于MADS-box转录因子（MADS-box transcription factor），其已知功能为调控开花时间。为明确玉米驯化过程中作为选择靶标的、由zagl1调控的性状，我们构建了一组重组染色体近等基因系（recombinant chromosome isogenic line）：该系列近等基因系在zagl1的栽培玉米等位基因与大刍草等位基因之间存在差异，且在zagl1与其邻近基因之间存在交叉互换事件。我们将该系列近等基因系开展随机化种植试验，并对开花时间及驯化相关性状进行了表型评分。结果显示，zagl1的栽培玉米等位基因与大刍草等位基因正如预期般对开花时间产生影响，同时还调控多个与果穗大小相关的性状：栽培玉米等位基因可使果穗更大、籽粒数量更多。本研究结果表明，在玉米驯化过程中，zagl1可能受到选择作用，以增大玉米果穗的尺寸。