cGMP dependent modulation of cation transport in plants

环核苷酸cGMP存在于植物细胞中。此外，它的浓度已被证明会对几种刺激做出5到10倍的反应，这表明它是真正的第二信使。cGMP在光敏色素信号、α -淀粉酶产生、防御反应和许多其他机制中发挥作用。此外，在一些研究中已经报道了cGMP参与离子通量的调节：原生质体暴露于膜渗透性cGMP导致Ca2+的快速流入；在气孔功能过程中，cGMP直接影响K+通量，从而引起气孔充盈变化；阳离子传导环核苷酸门控通道被环核苷酸激活；拟南芥根质膜非选择性离子通道受到cGMP的抑制。在组织水平上，净Na+摄取和Na+积累、Na+外排和K+摄取均受cGMP的影响。此外，我们最近发现cGMP调节许多基因的转录，特别是那些参与阳离子运输的基因。因此，本提案旨在以这些观察结果为基础，研究(i)哪些特定的转运蛋白参与了cGMP调节的Na+和K+通量，（ii）植物cGMP信号传导的基本原理是什么。最终，这些知识可能有助于理解植物矿物质营养的重要方面，如钾离子吸收和体内平衡，以及植物对盐胁迫的耐受性

The cyclic nucleotide cGMP is present in plant cells. In addition, its concentration has been shown to change 5 to 10-fold in response to several stimuli showing it acts as a true second messenger. cGMP has a role in phytochrome signalling, alpha-amylase production, defense responses and many other mechanisms. Furthermore, the participation of cGMP in the modulation of ionic fluxes has been reported in several studies: Exposure of protoplasts to membrane permeable cGMP led to a rapid influx of Ca2+; during stomatal functioning cGMP directly affects K+ fluxes that generate turgor changes; cation conducting cyclic nucleotide gated channels are activated by cyclic nucleotides; non-selective ion channels in Arabidopsis root plasma membranes are inhibited by cGMP. At the tissue level, net Na+ uptake and Na+ accumulation, Na+ efflux and K+ uptake are all affected by cGMP. In addition, we recently showed that cGMP modulates transcription of many genes particularly those involved in cation transport. This proposal is therefore aimed at building on these observations and to study (i) which specific transporters are involved in cGMP modulated Na+ and K+ fluxes and (ii) what the basic principles are of plant cGMP based signalling. Ultimately such knowledge may help in understanding important aspects of plant mineral nutrition such as K+ uptake and homeostasis, and plant tolerance to salinity stress