A conserved functional role of pectic polymers in stomatal guard cells from a range of plant species
A conserved functional role of pectic polymers in stomatal guard cells from a range of plant species
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DOI：
10.1007/s00425-004-1432-1
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发表时间：
2005-05-01
期刊：
影响因子：
4.3
通讯作者：
McQueen-Mason, SJ
中科院分区：
文献类型：
--
作者：
Jones, L;Milne, JL;McQueen-Mason, SJ
保护细胞壁结合了特殊的强度和灵活性，以适应膨胀压力驱动的大小和形状的变化，这是气孔打开和关闭的基础。为了研究这些特殊品质的分子基础，我们对三种不同的植物物种进行了组合和功能分析。我们表明，比较气孔保护细胞和其他表皮细胞的FTIR光谱表明细胞壁组成有许多明显的差异。最明显的特征是气孔保护细胞富含果胶酚酯。这种富集在蚕豆（具有I型细胞壁）、Commelina communis和玉米（具有II型细胞壁）的保护细胞中很明显。我们进一步表明，这些共同定义保护细胞壁的元素具有保守的功能作用。正如之前在C. communis中报道的那样，我们发现酶对蚕豆和Z. mays保护细胞壁上的果胶网络的修饰对气孔功能有深远的影响。表皮条与果胶甲基酯酶和内聚半乳糖醛酸酶（EPG）联合孵育后，气孔开度增大。当条带与EPG单独孵育时，没有看到这种效果，这表明均半乳糖醛酸的甲基化部分是这种效果的关键。相比之下，阿拉伯糖酶处理和阿魏酰酯酶孵育均阻碍气孔打开。因此，果胶和酚酯在保护细胞壁中具有保守的功能作用，即使在具有II型细胞壁的草物种中也是如此，II型细胞壁的特征是由低水平的果胶组成。
Guard cell walls combine exceptional strength and flexibility in order to accommodate the turgor pressure-driven changes in size and shape that underlie the opening and closing of stomatal pores. To investigate the molecular basis of these exceptional qualities, we have used a combination of compositional and functional analyses in three different plant species. We show that comparisons of FTIR spectra from stomatal guard cells and those of other epidermal cells indicate a number of clear differences in cell-wall composition. The most obvious characteristics are that stomatal guard cells are enriched in phenolic esters of pectins. This enrichment is apparent in guard cells from Vicia faba (possessing a type I cell wall) and Commelina communis and Zea mays (having a type II wall). We further show that these common defining elements of guard cell walls have conserved functional roles. As previously reported in C. communis, we show that enzymatic modification of the pectin network in guard cell walls in both V. faba and Z. mays has profound effects on stomatal function. In all three species, incubation of epidermal strips with a combination of pectin methyl esterase and endopolygalacturonase (EPG) caused an increase in stomatal aperture on opening. This effect was not seen when strips were incubated with EPG alone indicating that the methyl-esterified fraction of homogalacturonan is key to this effect. In contrast, arabinanase treatment, and incubation with feruloyl esterase both impeded stomatal opening. It therefore appears that pectins and phenolic esters have a conserved functional role in guard cell walls even in grass species with type II walls, which characteristically are composed of low levels of pectins.