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首页> 外文期刊>Journal of Experimental Botany >Permeability of Iris germanica's multiseriate exodermis to water, NaCl, and ethanol
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Permeability of Iris germanica's multiseriate exodermis to water, NaCl, and ethanol

机译：德国鸢尾的多重分泌物对水，NaCl和乙醇的渗透性

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The exodermis of Iris germanica roots is multiseriate. Its outermost layer matures first with typical Casparian bands and suberin lamellae. But as subsequent layers mature, the Casparian band extends into the tangential and anticlinal walls of their cells. Compared with roots in which the endodermis represents the major transport barrier, the multiseriate exodermis (MEX) was expected to reduce markedly radial water and solute transport. To test this idea, precocious maturation of the exodermis was induced with a humid air gap inside a hydroponic chamber. Hydraulic conductivity (Lp(pc)) was measured on completely submerged roots (with an immature exodermis) and on air-gap-exposed root regions (with two mature exodermal layers) using a pressure chamber. Compared with regions of roots with no mature exodermal layers, the mature MEX reduced Lp(pc) from 8.5x10(-8) to 3.9x10(-8) m s(-1) MPa-1. Puncturing the MEX increased Lp(pc) to 19x10(-8) m s(-1) MPa-1, indicating that this layer constituted a substantial hydraulic resistance within the root (75% of the total). Alternatively, a root pressure probe was used to produce pressure transients from which hydraulic conductivity was determined, but this device measured mainly flow through the endodermis in these wide-diameter roots. The permeability of roots to NaCl and ethanol was also reduced in the presence of two mature MEX layers. The data are discussed in terms of the validity of current root models and in terms of a potential role for I. germanica MEX during conditions of drought and salt stress.
机译：德国鸢尾根的外皮是多齿的。它的最外层首先具有典型的里海带和木栓薄片。但是随着后续层的成熟，里海带扩展到其细胞的切向壁和背斜壁。与内胚层代表主要运输障碍的根部相比，多系列外皮（MEX）有望显着减少径向水和溶质的运输。为了验证这一想法，在水培室内潮湿的空气间隙引起了外胚层的早熟。使用压力室在完全浸没的根部（具有未成熟的外皮）和气隙暴露的根部区域（具有两个成熟的表皮层）上测量水力传导率（Lp（pc））。与没有成熟外皮层的根部区域相比，成熟MEX将Lp（pc）从8.5x10（-8）降低到3.9x10（-8）m s（-1）MPa-1。穿破MEX将Lp（pc）增加到19x10（-8）m s（-1）MPa-1，表明该层在根部内构成了很大的水力阻力（占总阻力的75％）。或者，使用根压探头产生压力瞬变，从中确定水力传导率，但该设备主要测量的是流经这些宽直径根部的内胚层。在两个成熟的MEX层的存在下，根对NaCl和乙醇的渗透性也降低了。讨论了有关当前根模型的有效性以及干旱和盐胁迫条件下德国锗麦的潜在作用的数据。

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