Department of Horticulture, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Plant Physiol. 2011 Jul;156(3):1190-201. doi: 10.1104/pp.111.175489. Epub 2011 May 31.
Root cortical aerenchyma (RCA) is induced by hypoxia, drought, and several nutrient deficiencies. Previous research showed that RCA formation reduces the respiration and nutrient content of root tissue. We used SimRoot, a functional-structural model, to provide quantitative support for the hypothesis that RCA formation is a useful adaptation to suboptimal availability of phosphorus, nitrogen, and potassium by reducing the metabolic costs of soil exploration in maize (Zea mays). RCA increased the growth of simulated 40-d-old maize plants up to 55%, 54%, or 72% on low nitrogen, phosphorus, or potassium soil, respectively, and reduced critical fertility levels by 13%, 12%, or 7%, respectively. The greater utility of RCA on low-potassium soils is associated with the fact that root growth in potassium-deficient plants was more carbon limited than in phosphorus- and nitrogen-deficient plants. In contrast to potassium-deficient plants, phosphorus- and nitrogen-deficient plants allocate more carbon to the root system as the deficiency develops. The utility of RCA also depended on other root phenes and environmental factors. On low-phosphorus soils (7.5 μM), the utility of RCA was 2.9 times greater in plants with increased lateral branching density than in plants with normal branching. On low-nitrate soils, the utility of RCA formation was 56% greater in coarser soils with high nitrate leaching. Large genetic variation in RCA formation and the utility of RCA for a range of stresses position RCA as an interesting crop-breeding target for enhanced soil resource acquisition.
根皮层气腔（RCA）是由缺氧、干旱和多种营养缺乏诱导产生的。先前的研究表明，RCA 的形成会降低根组织的呼吸作用和养分含量。我们使用功能结构模型 SimRoot，为 RCA 形成是一种通过降低土壤探测的代谢成本来适应磷、氮和钾供应不足的有用适应的假说提供了定量支持，该假说适用于玉米（Zea mays）。RCA 分别使模拟的 40 天大的玉米植株的生长增加了 55%、54%或 72%，在低氮、磷或钾土壤上，分别降低了临界养分水平 13%、12%或 7%。RCA 在低钾土壤上的更大实用性与以下事实有关，即在缺钾植物中，根生长受到的碳限制比在缺磷和缺氮植物中更为严重。与缺钾植物不同，缺磷和缺氮植物随着缺乏的发展会将更多的碳分配到根系中。RCA 的实用性还取决于其他根系表型和环境因素。在低磷土壤（7.5 μM）上，与正常分枝植物相比，侧枝密度增加的植物中 RCA 的实用性增加了 2.9 倍。在低硝酸盐土壤上，在具有较高硝酸盐淋失的较粗土壤中，RCA 形成的实用性增加了 56%。RCA 形成的遗传变异很大，以及 RCA 在一系列胁迫下的实用性，使 RCA 成为增强土壤资源获取的一个有趣的作物育种目标。
