Soil textures rather than root hairs dominate water uptake and soil-plant hydraulics under drought
Soil textures rather than root hairs dominate water uptake and soil-plant hydraulics under drought
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DOI：
10.1093/plphys/kiab271
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发表时间：
2021-06-12
期刊：
影响因子：
7.4
通讯作者：
Ahmed, Mutez Ali
中科院分区：
文献类型：
--
作者：
Cai, Gaochao;Carminati, Andrea;Ahmed, Mutez Ali
虽然根毛（RH）在养分吸收中的作用是有据可查的，但它们在水分吸收和耐旱性中的作用仍然存在争议。玉米（玉蜀黍）野生型和它的头发缺陷突变体（Mut; roothairless 3）生长在两个对比的土壤质地（砂和壤土）。利用根压室测定了土壤干燥过程中蒸腾速率（E）与叶木质部水势（psi（leaf_x））的关系。我们的假设是：（1）在干旱土壤中，高E条件下，RHS延长了根-土接触，降低了psi（leaf_x）的下降;（2）RHS的影响在沙地中更为明显;（3）Mut通过产生更长和/或更粗的根，部分地补偿了RHS的缺乏。在湿润条件下，psi（leaf_x）（E）呈线性关系，随着土壤干燥，psi（leaf_x）（E）呈非线性关系。这种非线性发生更突然，在较少的负基质势在沙子（约。-10 kPa）比壤土（约. -100千帕）。当土壤基质势为负值时，两种土壤的导水率均小于根系导水率。两种基因型在壤土中表现出1.7倍的根长，但在砂中表现出1.6倍的根粗。两种基因型的psi（leaf_x）（E）关系和活跃根长无显著差异。在玉米中，RH有轻微的贡献，土壤中的土壤植物水力学和他们的假定作用，在水分吸收小于大麦（大麦）的报告。这些结果表明，RHS的作用不能很容易地概括跨物种和土壤质地影响根水力学土壤干燥的反应。
Although the role of root hairs (RHs) in nutrient uptake is well documented, their role in water uptake and drought tolerance remains controversial. Maize (Zea mays) wild-type and its hair-defective mutant (Mut; roothairless 3) were grown in two contrasting soil textures (sand and loam). We used a root pressure chamber to measure the relation between transpiration rate (E) and leaf xylem water potential (psi(leaf_x)) during soil drying. Our hypotheses were: (1) RHs extend root-soil contact and reduce the psi(leaf_x) decline at high E in dry soils; (2) the impact of RHs is more pronounced in sand; and (3) Muts partly compensate for lacking RHs by producing longer and/or thicker roots. The psi(leaf_x)(E) relation was linear in wet conditions and became nonlinear as the soils dried. This nonlinearity occurred more abruptly and at less negative matric potentials in sand (ca. -10 kPa) than in loam (ca. -100 kPa). At more negative soil matric potentials, soil hydraulic conductance became smaller than root hydraulic conductance in both soils. Both genotypes exhibited 1.7 times longer roots in loam, but 1.6 times thicker roots in sand. No differences were observed in the psi(leaf_x)(E) relation and active root length between the two genotypes. In maize, RHs had a minor contribution to soil-plant hydraulics in both soils and their putative role in water uptake was smaller than that reported for barley (Hordeum vulgare). These results suggest that the role of RHs cannot be easily generalized across species and soil textures affect the response of root hydraulics to soil drying.