【作者】 李斌；

【导师】 郝建平； 武维华；

【作者基本信息】 山西大学 ， 植物学， 2005， 硕士

【摘要】 ABA介导的信号转导途径和G蛋白介导的信号转导途径是植物细胞两类重要的细胞信号转导机制。研究证明,ABA可以通过抑制细胞质膜内向钾离子通道而抑制光照下植物叶片气孔的开放。G蛋白偶联受体是G蛋白信号转导途径中的重要组分,在动物细胞中有许多重要功能,而在植物中研究不多。 气孔保卫细胞是研究植物细胞信号转导的理想模型。为了揭示上述两类细胞信号转导途径之间存在的联系,研究G蛋白偶联受体是否参与了植物ABA信号转导途径和可能的作用机制,本论文以拟南芥假定G蛋白偶联受体GCR2基因缺失突变体gcr2-1和过量表达突变体35S∷GCR2为材料,采用气孔开度实验和细胞膜片钳技术,比较了外加50μmol/L ABA处理前后,突变体和野生型植株气孔的开度和保卫细胞原生质体内向钾离子通道电流的变化。 表皮条气孔开度实验结果表明,光照下野生型叶片气孔在经外加50μmol/L ABA处理以后,开放受到显著抑制。与此不同的是,gcr2-1的气孔对ABA反应不敏感,仍然受光照诱导正常开放;而35S∷GCR2则表现为对ABA反应超敏感,比野生型抑制的程度更大。 膜片钳实验结果表明,野生型保卫细胞原生质体的内向钾离子通道电流被50μmol/L ABA抑制38%左右;而gcr2-1内向钾离子通道电流被ABA抑制的现象消失;35S∷GCR2的通道电流也表现出对外加ABA作用的不敏感。 以上实验结果初步证明,假定的拟南芥G蛋白偶联受体GCR2参与了ABA对保卫细胞内向钾离子通道的调控过程,并通过该方式影响了ABA对气孔关闭的诱导。更多还原

【Abstract】 The ABA-regulated and G-proein-regulated cell sigal transductions are two important cell signal transduction systems in plant cell. It has been reported that ABA is one of the important phytohormes in the regulation of in ward-rectify potassium (K+in) channels thus control the stomatal movements. G protein coupled receptor is one of important elements in G protein signal transduction pathway. It plays many important roles in mammalian cells, but seldom was studied in plant cells.The guard cell is a model system for studying cell sigal transduction in plants. In order to study the relationship between the two sigal transduction pathways and find out if the K+in channel of guard cells in mutants displayed the different manners with wild type plants to the extracellular ABA or if the GCR2 was involved in the ABA signal transduction process, the techniques as stomatal eperture measurment and patch clamping method were employed, the Arabidopsis thaliana plant mutants of the the GCR2 as gcr2-l and 35S..GCR2 were tested in this work as well as the wild type.Results of stomatal aperture assay showed that gcr2-l stomata exhibit hyposensitivety relative to wild type, however 35S::GCR2 shows hyper-sensitivity to extracellular 50 [imol/L ABA.By application of patch clamp technique, the voltage-dependent inward-rectify potassium currents were recorded and characterized. The K+in current of the guard cells of the wild plants was inhibited by 50 u.mol/L extracellular ABA for about 38% at the voltage -180 mV, but the inhibition of ABA was abolished in the current of gcr2-l guard cells.The K+in current of the mutant as 35S::GCR2 was also tested, and the results showed that from the current traces and the I/V curves of the 35S::GCR2 and wild type guard cells, there is no significant difference between the two materials under the test of extracelluar ABA.It is concluded that putative G-protein coupled receptor, GCR2, is somehow involved in the process of ABA regulated guard cell inward更多还原