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

PnGLP是一种基因，其转录产物在短日照敏感植物P.nil cv的叶片和子叶中积累。该基因编码GLP基因叶型亚家族中的一个成员。GLP蛋白的功能大多尚不清楚。Northern分析表明，PnGLP基因的表达呈现昼夜节律，在暗期开始后10h左右达到最大值，并且这种振荡持续时间延长。在Aratidcpsis(Long-day plait)中分离到PnGLP的同源物AtGLP1和AtGLP2，并表征了AtGLP1和AtGLP2在叶片中的积累也表现出昼夜节律，在光照开始后14h左右达到最大值。这些振荡大多在连续光照下持续。AtGLP1和AtGLP2的调控方式与PnGLP相反，可能反映了短日照植物和长日照植物的差异。为了研究与光周期有关的叶型GLP gsne调控的机制，我们决定以荧光素酶基因为报告基因来分析这些基因的启动子区域。由于这些序列之间没有保守的顺式结构，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昼夜节律表达所必需的。测定PnGLP对光周期诱导开花的影响。我们正在对表达PnGLP基因的转基因植物进行研究。我们使用的是短日照烟草(Nicotiona tabacum cv.Mammoth)作为寄主植物，与对照相比，表达PnGLP基因的烟草植株更有可能形成花穗。表达PnGLP基因的烟草植株很可能作为光周期诱导短日照植株开花的温和刺激剂。我们的实验目前正在基于这样的假设进行。

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.