Blue-light regulation of ZmPHOT1 and ZmPHOT2 gene expression and the possible involvement of Zmphot1 in phototropism in maize coleoptiles
Blue-light regulation of ZmPHOT1 and ZmPHOT2 gene expression and the possible involvement of Zmphot1 in phototropism in maize coleoptiles
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DOI：
10.1007/s00425-014-2082-6
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发表时间：
2014-05
期刊：
影响因子：
4.3
通讯作者：
Hiromi Suzuki;Aiko Okamoto;Akane Kojima;Takeshi Nishimura;M. Takano;T. Kagawa;A. Kadota;T. Kanegae;T. Koshiba
中科院分区：
文献类型：
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作者：
Hiromi Suzuki;Aiko Okamoto;Akane Kojima;Takeshi Nishimura;M. Takano;T. Kagawa;A. Kadota;T. Kanegae;T. Koshiba
主要结论ZmPHOT 1和ZmPHOT 2在玉米胚芽鞘和叶片中的表达存在差异，ZmPHOT 1可能参与了低通量脉冲蓝光下玉米胚芽鞘的第一正向光性弯曲，向光性蛋白（s）的单侧蓝光感知是第一个向光性事件，随后的信号导致生长素在单子叶植物胚芽鞘顶端区域的侧向运输。在这项研究中，我们分析了两个玉米向光蛋白基因：ZmPHOT 1和ZmPHOT 2，后者从玉米基因组数据库中鉴定和新的特点。实时荧光定量PCR分析表明，ZmPHOT 1在黄化的胚芽鞘中大量表达，而ZmPHOT 1和ZmPHOT 2在幼叶中的表达量较低。有趣的是，这些基因在胚芽鞘尖端区域没有特异性表达，而胚芽鞘尖端区域是向光性中光感知的关键位置。暴露于脉冲低通量蓝光（LBL）（0.33 µmol m−2s−1× 8 s）和连续高通量蓝光（HBL）（10 µmol m−2s−1）可迅速降低胚芽鞘中ZmPHOT 1基因的表达，而该组织中ZmPHOT 2的水平没有显著改变。在幼叶中，LBL或HBL辐照均未诱导ZmPHOT 1或ZmPHOT 2的表达发生剧烈变化。Zmphot1蛋白用抗Ospot 1抗体通过Western印迹分析进行研究。在微粒体组分中检测到Zmphot1，胚芽鞘中的水平高于叶片。HBL引起的蛋白质的快速磷酸化，而没有phot1磷酸化诱导LBL。讨论了Zmphot1在LBL诱导的玉米胚芽鞘向光弯曲中的作用。
Main conclusionZmPHOT1andZmPHOT2are expressed differentially in maize coleoptiles and leaves, with Zmphot1 possibly involved in first-positive phototropic curvature of red-light-adapted maize coleoptiles exposed to pulsed low-fluence blue light.Unilateral blue-light perception by phototropin(s) is the first event of phototropism, with the subsequent signal causing lateral transport of auxin at the coleoptile tip region of monocots. In this study, we analyzed the behavior of two maize phototropin genes:ZmPHOT1andZmPHOT2, the latter identified from the maize genome database and newly characterized. Quantitative real-time PCR analysis demonstrated thatZmPHOT1was abundantly expressed in etiolated coleoptiles, while lower expressions of bothZmPHOT1andZmPHOT2were observed in young leaves. Interestingly, these genes were not specifically expressed in the coleoptile tip region, a key position for photoperception in phototropism. Exposure to pulsed low-fluence blue light (LBL) (0.33 µmol m−2s−1× 8 s) and continuous high-fluence blue light (HBL) (10 µmol m−2s−1) rapidly decreasedZmPHOT1gene expression in coleoptiles, with levels ofZmPHOT2not significantly altered in that tissue. In young leaves, no drastic expression changes were induced in eitherZmPHOT1orZmPHOT2by LBL or HBL irradiation. The Zmphot1 protein was investigated by Western blot analysis with anti-Osphot1 antibodies. Zmphot1 was detected in microsomal fractions, with higher levels in coleoptiles than in leaves. HBL caused rapid phosphorylation of the protein, whereas no phot1 phosphorylation was induced by LBL. The involvement of Zmphot1 in LBL-induced phototropic curvature of maize coleoptiles is discussed.