Zhao Han, Luo Rong, Cai Jing, Ning Qiurui, Gong Xuewei, Jiang Zaimin
College of Forestry, Northwest A&F University, Yangling, China.
Planning and Natural Resources Bureau of Danling County, Meishan, China.
Plant Cell Environ. 2025 Mar 27. doi: 10.1111/pce.15512.
Breeding productive tree genotypes is crucial for sustainable forestry, yet the hydraulic architecture along root-stem-leaf continuum that constrains biomass yield remains unclear. Here, six poplar hybrid genotypes with contrasting yield were used to quantify whole-plant hydraulic resistance, its partitioning patterns, and anatomical traits along the continuum. We observed substantial genetic variations in hydraulic resistance parameters. Roots contributed the largest proportion of whole-plant hydraulic resistance (> 54%). Components along the continuum were well-coordinated, and hydraulic resistance of all components was strongly correlated with yield (R > 0.75), suggesting that hydraulic resistance is a strong predictor of yield. However, resistance partitioning patterns generally showed weak correlations with yield, with more productive genotypes partitioning a smaller proportion of resistance to leaves. Vessel diameter was a key determinant of hydraulic resistance at the root and leaf levels (R ≥ 0.75), and vessel length significantly influenced stem hydraulic resistance (R = 0.80). Additionally, genotypes with higher minor vein density and a lower ratio of palisade to spongy mesophyll thickness exhibited lower leaf resistance. Our results suggest that low hydraulic resistance throughout root-stem-leaf continuum is the functional basis for high yield, and the identification of key hydraulic and structural constraints will help overcome bottlenecks in breeding productive tree genotypes.
培育高产的树木基因型对于可持续林业至关重要，然而，沿根 - 茎 - 叶连续体的水力结构限制生物量产量的情况仍不清楚。在此，使用六种产量不同的杨树杂交基因型来量化全株水力阻力、其分配模式以及沿连续体的解剖学特征。我们观察到水力阻力参数存在显著的遗传变异。根部对全株水力阻力的贡献最大（> 54%）。连续体上的各个部分协调良好，所有部分的水力阻力都与产量密切相关（R > 0.75），这表明水力阻力是产量的一个强有力的预测指标。然而，阻力分配模式通常与产量的相关性较弱，高产基因型对叶片分配的阻力比例较小。导管直径是根和叶水平水力阻力的关键决定因素（R ≥ 0.75），导管长度显著影响茎的水力阻力（R = 0.80）。此外，小叶脉密度较高且栅栏组织与海绵组织叶肉厚度比值较低的基因型表现出较低的叶片阻力。我们的结果表明，根 - 茎 - 叶连续体上的低水力阻力是高产的功能基础，识别关键的水力和结构限制将有助于克服培育高产树木基因型过程中的瓶颈。
