Capparis odoratissima is a tree species native to semi‐arid environments of South America where low soil water availability coexists with frequent night‐time fog. A previous study showed that water applied to leaf surfaces enhanced leaf hydration, photosynthesis and growth, but the mechanisms of foliar water uptake are unknown. Here, we combine detailed anatomical evaluations with water and dye uptake experiments in the laboratory, and use immunolocalization of pectin and arabinogalactan protein epitopes to characterize water uptake pathways in leaves. Abaxially, the leaves of C. odoratissima are covered with peltate hairs, while the adaxial surfaces are glabrous. Both surfaces are able to absorb condensed water, but the abaxial surface has higher rates of water uptake. Thousands of idioblasts per cm², a higher density than stomata, connect the adaxial leaf surface and the abaxial peltate hairs, both of which contain hygroscopic substances such as arabinogalactan proteins and pectins. The highly specialized anatomy of the leaves of C odoratissima fulfils the dual function of minimizing water loss when stomata are closed, while maintaining the ability to absorb liquid water. Cell‐wall related hygroscopic compounds in the peltate hairs and idioblasts create a network of microchannels that maintain leaf hydration and promote water uptake.

中文翻译：

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Idioblasts 和盾状毛作为干旱叶吸收水的分配网络

Capparis odoratissima是一种原产于南美洲半干旱环境的树种，那里土壤水分含量低，夜间经常有雾。先前的一项研究表明，施用于叶面的水增强了叶片的水合作用、光合作用和生长，但叶面吸水的机制尚不清楚。在这里，我们将详细的解剖学评估与实验室中的水和染料吸收实验相结合，并使用果胶和阿拉伯半乳聚糖蛋白表位的免疫定位来表征叶子中的水吸收途径。背面，C. odoratissima的叶子被盾状毛覆盖，而正面无毛。两个表面都能够吸收冷凝水，但背面的吸水率更高。每厘米²数以千计的成纤维细胞，密度高于气孔，连接着叶正面和背面的盾状毛，两者都含有吸湿性物质，如阿拉伯半乳聚糖蛋白和果胶。C odoratissima叶子的高度专业化解剖结构具有双重功能，即在气孔关闭时最大限度地减少水分流失，同时保持吸收液态水的能力。盾状毛和成虫细胞中与细胞壁相关的吸湿性化合物形成了一个微通道网络，可维持叶片水合作用并促进水分吸收。