A Tandem Amino Acid Residue Motif in Guard Cell SLAC1 Anion Channel of Grasses Allows for the Control of Stomatal Aperture by Nitrate
A Tandem Amino Acid Residue Motif in Guard Cell SLAC1 Anion Channel of Grasses Allows for the Control of Stomatal Aperture by Nitrate
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DOI：
10.1016/j.cub.2018.03.027
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发表时间：
2018-05
期刊：
影响因子：
9.2
通讯作者：
Nadine Schäfer;T. Maierhofer;Johannes Herrmann;M. E. Jørgensen;Christof Lind;K. Meyer;S. Lautner
中科院分区：
文献类型：
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作者：
Nadine Schäfer;T. Maierhofer;Johannes Herrmann;M. E. Jørgensen;Christof Lind;K. Meyer;S. Lautner
最新进化的主要植物类群是草类。这些在大约 4000 万年前的古近纪中期变得很重要。在进化过程中，叶子的二氧化碳吸收和蒸腾失水通过获得草特有的气孔复合体而得到优化。与拟南芥等双子叶植物中典型的肾形保卫细胞 (GC) 不同，在禾本科植物和农学上重要的谷物中，GC 呈哑铃形，并与形态上不同的辅助细胞 (SC) 相关。我们研究了主要谷类作物大麦中 GC 作用的分子基础。将 ABA 喂入完整大麦叶的木质部汁液后，气孔以硝酸盐依赖性方式关闭。该过程是通过激活 GC SLAC 型阴离子通道电流来启动的。 HvSLAC1 在爪蟾细胞中表达，产生 S 型阴离子电流，在 > 3 mM 硝酸盐刺激后，该电流增加数倍。我们鉴定了 SLAC1 通道内的串联氨基酸残基基序，该基序在单子叶植物和双子叶植物之间存在根本差异。当对硝酸盐不敏感的双子叶植物拟南芥SLAC1的基序被单子叶植物特征取代时，AtSLAC1转化为草型的硝酸盐敏感通道。我们的工作揭示了单子叶植物和双子叶植物 GC 之间的根本区别，并引发了对进化过程中选择性压力的疑问，这种压力导致了 SLAC1 功能调节的根本变化。
The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution, leaf CO2uptake and transpirational water loss were optimized by the acquisition of grass-specific stomatal complexes. In contrast to the kidney-shaped guard cells (GCs) typical of the dicots such asArabidopsis, in the grasses and agronomically important cereals, the GCs are dumbbell shaped and are associated with morphologically distinct subsidiary cells (SCs). We studied the molecular basis of GC action in the major cereal crop barley. Upon feeding ABA to xylem sap of an intact barley leaf, stomata closed in a nitrate-dependent manner. This process was initiated by activation of GC SLAC-type anion channel currents. HvSLAC1 expressed inXenopusoocytes gave rise to S-type anion currents that increased several-fold upon stimulation with >3 mM nitrate. We identified a tandem amino acid residue motif that within the SLAC1 channels differs fundamentally between monocots and dicots. When the motif of nitrate-insensitive dicotArabidopsisSLAC1 was replaced by the monocot signature, AtSLAC1 converted into a grass-type like nitrate-sensitive channel. Our work reveals a fundamental difference between monocot and dicot GCs and prompts questions into the selective pressures during evolution that resulted in fundamental changes in the regulation of SLAC1 function.