Flowering in maize (Zea mays) is influenced by photoperiod. The CO, CO-like/COL and TOC1 (CCT) domain protein-encoding genes in maize, ZmCCTs, are particularly important for photoperiod sensitivity. However, little is known about CCT protein-encoding gene number across plant species or among maize inbred lines. Therefore, we analysed CCT protein-encoding gene number across plant species, and characterized ZmCCTs in different inbred lines, including structural variations (SVs), copy number variations (CNVs), expression under stresses, dark-dark (DD) and dark-light (DL) cycles, interaction network and associations with maize quantitative trait loci (QTLs) by referring to the latest v4 genome data of B73. Gene number varied greatly across plant species, more in polyploids than in diploids. The numbers of ZmCCTs identified were 58 in B73, 59 in W22, 48 in Mo17, and 57 in Huangzao4 for temperate maize inbred lines, and 68 in tropical maize inbred line SK. Some ZmCCTs underwent duplications and presented chromosome collinearity. Structural variations and CNVs were found but they had no germplasm specificity. Forty-two ZmCCTs responded to stresses. Expression of 37 ZmCCTs in embryonic leaves during seed germination of maize under DD and DL cycles was roughly divided into five patterns of uphill pattern, downhill-pattern, zigzag-pattern, └-pattern and ⅃-pattern, indicating some of them have a potential to perceive dark and/or dark-light transition. Thirty-three ZmCCTs were co-expressed with 218 other maize genes; and 24 ZmCCTs were associated with known QTLs. The data presented in this study will help inform further functions of ZmCCTs.

中文翻译：

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开放获取多组学数据集的分析揭示了玉米 ZmCCT 家族基因的遗传和表达特征


玉米（Zea mays）的开花受光周期的影响。玉米中的 CO、CO-like/COL 和 TOC1 (CCT) 结构域蛋白编码基因 ZmCCT 对于光周期敏感性特别重要。然而，人们对跨植物物种或玉米自交系中 CCT 蛋白编码基因的数量知之甚少。因此，我们分析了植物物种中CCT蛋白编码基因的数量，并对不同自交系中的ZmCCT进行了表征，包括结构变异（SV）、拷贝数变异（CNV）、胁迫、暗-暗（DD）和暗-光下的表达参考B73最新v4基因组数据，研究了（DL）循环、交互网络以及与玉米数量性状位点（QTL）的关联。不同植物物种的基因数量差异很大，多倍体的基因数量比二倍体的基因数量差异更大。温带玉米自交系中鉴定出的 ZmCCT 数量为 B73 58 个、W22 59 个、Mo17 48 个、黄早 4 号 57 个，热带玉米自交系 SK 68 个。一些 ZmCCT 发生重复并呈现染色体共线性。发现了结构变异和CNV，但它们没有种质特异性。 42 个 ZmCCT 对压力做出了反应。 DD和DL循环下玉米种子萌发过程中37个ZmCCT在胚叶中的表达大致分为上坡型、下坡型、锯齿型、└型和⅃型5种模式，表明其中一些具有潜在的潜力感知黑暗和/或暗光过渡。 33 个 ZmCCT 与 218 个其他玉米基因共表达； 24 个 ZmCCT 与已知的 QTL 相关。本研究中提供的数据将有助于了解 ZmCCT 的进一步功能。