Analysis of GLP (germin-like protein) genes related to photoperiodic response

PnGLP（Pharbitisnil gemin-like protein）是一个在短日照植物牵牛（P.nil cv.）紫色在花诱导的黑暗时期，并编码GLP基因的叶型亚家族的成员。GLP蛋白的功能大多是未知的。北方分析表明，PnGLP mRNA的水平表现出昼夜节律，在黑暗期开始后10 h左右达到最大值，并且这种振荡在延长的连续黑暗中继续。分离并鉴定了Aratidcpsis（along-day plait）中PnGLP的同源物AtGLP 1和AtGLP 2。AtGLP 1和AtGLP 2 mRNA在叶片中的积累也具有昼夜节律，在光照开始后14 h左右达到最大值。这些振荡主要在连续光照下持续进行。AtGLP 1和AtGLP 2的调控模式与PnGLP相反，可能反映了短日植物与长日植物的差异。为了研究叶型GLP gsne调控与光周期的关系，我们决定以荧光素酶基因为报告基因，分析这些基因的启动子区。由于这些promoteis之间没有保守的顺式元件，我们目前正在分析一系列的启动子缺失结构，以确定哪些序列基序是必不可少的昼夜节律表达。测定PnGLP对光周期诱导开花的影响。我们目前正在研究表达PnGLP cDNA的转基因植物。以短日照烟草（Nicotiona tabacum cv.马里兰州猛犸）作为寄主植物，与对照相比，表达PnGLP cDNA的烟草植株更容易形成花穗。表达PnGLP cDNA的烟草植株可能是短日照植物光周期诱导开花的温和刺激物。我们的实验目前正在进行这种假设。

PnGLP (Pharbitis nil gemin-like protein) is a gene whose transcript is accumulated in leaves and cotyledons of the very sensitive short-day plant, P. nil cv. Violet during the flower-inductive dark-period and encodes a member of the leaf-type subfamily of GLP genes. The functions of GLP proteins are mostly unkown. Northern analysis revealed that the level of PnGLP mRNA showed a circadian rhythm, with maxima around 10 h after the beginning of the dark period, and this oscillation continued in lengthened continuous daikness. Homologues of PnGLP in Aratidcpsis (along-day plait), namely, AtGLP1 and AtGLP2 were isolated and characterized Accumulation of AtGLP1 and AtGLP2 mRNA in leafalso showed circadian rhythms, with maxima around 14 h after the beginning of the light period. These oscillaticns continued mostly under continuous light. The mode of regulation in AtGLP1 and AtGLP2 showed opposite to that of PnGLP, possibly reflecting the differences between short-day plants and long-day plants. To study the mdecularmechanisms ofleaf-type GLP gsne regulation in relati on to photoperiodism, we decided to analyze promoter region ofthese genes using a luciferase gene as a reporter. Because there were no conserved cis-lements among these ptomoteis, we are currently analyzing a series of promoter deletion constructs to identify which sequence motif is essential for circadian rhythmic expression. To deteimine the effects of PnGLP to photoperiodic induction of flowering. we are cumently studying tiansgenic plants expressing PnGLP cDNA. We used short-day tobacco plant (Nicotiona tabacum cv. Maryland Mammoth) as a host plant Tobacco plants that express PnGLP cDNA were likely to form flower earHerwhen they compared to control plant. Tobacco plants that express PnGLP cDNA were likely to from works as a mild stimulator for photoperiodic induction of flowering in short-day plants. Our experiment is currently underway on such hypothesis.