Schneider Hannah M, Yang Jennifer T, Brown Kathleen M, Lynch Jonathan P
Department of Plant Science The Pennsylvania State University University Park PA USA.
Present address: Wellesley College Wellesley MA USA.
Plant Direct. 2021 Mar 16;5(3):e00310. doi: 10.1002/pld3.310. eCollection 2021 Mar.
Under nitrogen limitation, plants increase resource allocation to root growth relative to shoot growth. The utility of various root architectural and anatomical phenotypes for nitrogen acquisition are not well understood. Nodal root number and root cross-sectional area were evaluated in maize in field and greenhouse environments. Nodal root number and root cross-sectional area were inversely correlated under both high and low nitrogen conditions. Attenuated emergence of root nodes, as opposed to differences in the number of axial roots per node, was associated with substantially reduced root number. Greater root cross-sectional area was associated with a greater stele area and number of cortical cell files. Genotypes that produced few, thick nodal roots rather than many, thin nodal roots had deeper rooting and better shoot growth in low nitrogen environments. Fewer nodal roots offset the respiratory and nitrogen costs of thicker diameter roots, since total nodal root respiration and nitrogen content was similar for genotypes with many, thin and few, thick nodal roots. We propose that few, thick nodal roots may enable greater capture of deep soil nitrogen and improve plant performance under nitrogen stress. Synergistic interactions between an architectural and anatomical trait may be an important strategy for nitrogen acquisition. Understanding trait interactions among different root nodes has important implications in for improving crop nutrient uptake and stress tolerance.
在氮素限制条件下，植物相对于地上部生长会增加对根系生长的资源分配。目前对于各种根系结构和解剖学表型在氮素获取方面的作用还了解不足。在田间和温室环境中对玉米的节根数量和根横截面积进行了评估。在高氮和低氮条件下，节根数量和根横截面积均呈负相关。与每个节上轴根数量的差异不同，根节出现减弱与根数量大幅减少有关。更大的根横截面积与更大的中柱面积和皮层细胞层数有关。在低氮环境中，产生少量粗节根而非许多细节根的基因型具有更深的根系和更好的地上部生长。较少的节根抵消了较粗直径根的呼吸和氮成本，因为具有许多细节根和少量粗节根的基因型的总节根呼吸和氮含量相似。我们提出，少量粗节根可能有助于更好地获取深层土壤中的氮，并改善氮胁迫下的植物性能。根系结构和解剖学性状之间的协同相互作用可能是氮素获取的重要策略。了解不同根节之间的性状相互作用对于提高作物养分吸收和胁迫耐受性具有重要意义。
