Stomatal Function Requires Pectin De-methyl-esterification of the Guard Cell Wall.
Stomatal Function Requires Pectin De-methyl-esterification of the Guard Cell Wall.
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DOI：
10.1016/j.cub.2016.08.021
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发表时间：
2016-11-07
期刊：
影响因子：
9.2
通讯作者：
Gray, Julie E.
中科院分区：
文献类型：
--
作者：
Amsbury, Sam;Hunt, Lee;Elhaddad, Nagat;Baillie, Alice;Lundgren, Marjorie;Verhertbruggen, Yves;Scheller, Henrik V.;Knox, J. Paul;Fleming, Andrew J.;Gray, Julie E.
气孔的打开和关闭取决于保卫细胞内膨压的变化来改变细胞形状。这些形状变化的程度受到细胞的机械性质的限制，这将在很大程度上取决于细胞壁的结构。虽然长期以来已经观察到，由于差异增厚和纤维素微纤丝的取向，保卫细胞是各向异性的，但我们对允许它们经历反复膨胀和收缩的细胞壁的组成的理解仍然令人惊讶地差。在这里，我们表明，保卫细胞的壁富含未酯化的果胶。我们确定了果胶甲酯酶基因，PME 6，这是高度表达的保卫细胞和气孔功能所需的。PME 6 -1突变体保卫细胞具有富含甲基酯化果胶的细胞壁，并显示出响应于气孔打开/关闭的触发（包括升高的果胶）的降低的动态范围，这表明气孔功能的消除反映了保卫细胞壁的机械变化。气孔功能的改变导致传导性和蒸发冷却的增加，以及植物生长的降低。pme 6 -1突变体的生长缺陷被救出，通过保持植物在升高的CO2，证实气体交换分析，表明突变体气孔可以赋予一个改善的同化率。PME 6的恢复拯救保卫细胞壁果胶甲酯化状态、气孔功能和植物生长。我们的研究结果建立了保卫细胞基因表达和细胞壁特性之间的联系，对气孔功能和植物生理产生相应的影响。保卫细胞壁的特点是甲基化果胶水平相对较低，甲基化果胶的增加导致气孔运动的动态范围较小。这些植物在干旱条件下表现出蒸发冷却增加和生长下降。CO2浓度升高使突变植物生长恢复正常保卫细胞壁的力学必须在设置气孔运动的动态中发挥作用。Amsbury等人表明壁中果胶甲基化的程度设定了细胞膨胀的范围，植物水分利用和生长的后果取决于CO2水平。气孔机制可能影响植物对气候变化的反应。
Stomatal opening and closure depends on changes in turgor pressure acting within guard cells to alter cell shape. The extent of these shape changes is limited by the mechanical properties of the cells, which will be largely dependent on the structure of the cell walls. Although it has long been observed that guard cells are anisotropic due to differential thickening and the orientation of cellulose microfibrils, our understanding of the composition of the cell wall that allows them to undergo repeated swelling and deflation remains surprisingly poor. Here, we show that the walls of guard cells are rich in un-esterified pectins. We identify a pectin methylesterase gene, PME6, which is highly expressed in guard cells and required for stomatal function. pme6-1 mutant guard cells have walls enriched in methyl-esterified pectin and show a decreased dynamic range in response to triggers of stomatal opening/closure, including elevated osmoticum, suggesting that abrogation of stomatal function reflects a mechanical change in the guard cell wall. Altered stomatal function leads to increased conductance and evaporative cooling, as well as decreased plant growth. The growth defect of the pme6-1 mutant is rescued by maintaining the plants in elevated CO2, substantiating gas exchange analyses, indicating that the mutant stomata can bestow an improved assimilation rate. Restoration of PME6 rescues guard cell wall pectin methyl-esterification status, stomatal function, and plant growth. Our results establish a link between gene expression in guard cells and their cell wall properties, with a corresponding effect on stomatal function and plant physiology. The guard cell wall is distinguished by a relatively low level of methylated pectin Increased methyl pectin leads to stomata with a smaller dynamic range of movement These plants show increased evaporative cooling and decreased growth under drought Elevated CO2 restores mutant plant growth to normal Guard cell wall mechanics must play a role in setting the dynamics of stomatal movement. Amsbury et al. show that the degree of pectin methylation in the wall sets the range of cell swelling, with consequences for plant water use and growth being dependent on CO2 level. Stomatal mechanics are likely to influence plant response to climate change.
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影响因子：
9.2
作者：
Negi, Juntaro;Moriwaki, Kosuke;Konishi, Mineko;Yokoyama, Ryusuke;Nakano, Toshiaki;Kusumi, Kensuke;Hashimoto-Sugimoto, Mimi;Schroeder, Julian I.;Nishitani, Kazuhiko;Yanagisawa, Shuichi;Iba, Koh
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影响因子：
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作者：
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影响因子：
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