USDA-ARS Sugarcane unit, Houma, Louisiana, USA.
School of Biological Sciences, Washington State University, Pullman, Washington, USA.
Plant Cell Environ. 2023 Sep;46(9):2694-2710. doi: 10.1111/pce.14612. Epub 2023 May 23.
Measurements of oxygen isotope enrichment of leaf water above source water (Δ O ) can improve our understanding of the interaction between leaf anatomy and physiology on leaf water transport. Models have been developed to predict Δ O such as the string-of-lakes model, which describes the mixing of leaf water pools, and the Péclet effect model, which incorporates transpiration rate and the mixing length between unenriched xylem and enriched mesophyll water in the mesophyll (L ) or veins (L ). Here we compare measurements and models of Δ O on two cell wall composition mutants grown under two light intensities and relative humidities to evaluate cell wall properties on leaf water transport. In maize (Zea mays), the compromised ultrastructure of the suberin lamellae in the bundle sheath of the ALIPHATIC SUBERIN FERULOYL TRANSFERASE mutant (Zmasft) reduced barriers to apoplastic water movement, resulting in higher E and, potentially, L and, consequently, lower Δ O . The difference in Δ O in cellulose synthase-like F6 (CslF6) mutants and wild-type of rice (Oryza sativa) grown under two light intensities co-varied with stomatal density. These results show that cell wall composition and stomatal density influence Δ O and that stable isotopes can facilitate the development of a physiologically and anatomically explicit water transport model.
测量源水上方叶片水的氧同位素富集度（ΔO）可以增进我们对叶片解剖结构和生理特性影响叶片水分运输的相互作用的理解。已经开发出一些模型来预测 ΔO，例如串湖模型，它描述了叶片水池的混合，以及佩克莱效应模型，它将蒸腾速率和未富化木质部与富含质膜水之间的混合长度纳入质膜（L）或叶脉（L）中。在这里，我们比较了两种细胞壁组成突变体在两种光照强度和相对湿度下的 ΔO 测量值和模型，以评估细胞壁特性对叶片水分运输的影响。在玉米（Zea mays）中，ALIPHATIC SUBERIN FERULOYL TRANSFERASE 突变体（Zmasft）中栓内层的超微结构受损，降低了质外体水分运动的障碍，导致更高的 E，并且可能更高的 L，从而导致更低的 ΔO。在两种光照强度下生长的纤维素合酶样 F6（CslF6）突变体和野生型水稻（Oryza sativa）的 ΔO 差异与气孔密度有关。这些结果表明，细胞壁组成和气孔密度会影响 ΔO，并且稳定同位素可以促进具有生理学和解剖学明确性的水分运输模型的发展。
