School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
Plant Cell Environ. 2023 Oct;46(10):3023-3039. doi: 10.1111/pce.14470. Epub 2022 Nov 7.
Combining plant growth analysis with a simple model of local resource capture and biomass allocation applied to exemplary experimental data, showed that dynamic changes in allocation to roots when nutrients are scarce is caused by disparities in growth rates between roots and shoots. Whole-plant growth rates also change but are not caused by an adaptive allocation response. Allocation and whole-plant growth rate are interdependent, not independent, traits. Following a switch in nutrient availability or partial biomass removal, convergence of allocation and growth rate trajectories does not reflect goal-seeking behaviour, but the constraints imposed by finite resource availability. Optimal root-shoot allocations are unnecessary to maximise whole-plant growth rate. Similar growth rates are attainable with different allocations. Changes in allocation cannot maintain or restore a superior whole-plant growth rate. Roots and shoots do not have to be tightly coordinated but can operate semiautonomously, as their modular construction permits. These findings question the plausibility of the prevailing general explanation of plants' root-shoot allocation responses, 'optimal partitioning theory' (OPT). Local allocation models, not OPT, explain the origins of variability in root-shoot trade-offs in individuals, the allocation of biomass at global and ecosystem scales and inform selection for allocation plasticity in crop breeding.
将植物生长分析与局部资源捕获和生物量分配的简单模型相结合，并应用于典型的实验数据，结果表明，在养分匮乏时根系分配的动态变化是由根和茎之间的生长速率差异引起的。整个植物的生长速率也会发生变化，但不是由适应性分配反应引起的。分配和整个植物的生长速率是相互依存的，而不是独立的特征。在养分供应的转变或部分生物量去除后，分配和生长速率轨迹的收敛并不反映目标寻求行为，而是受到有限资源供应的限制。最优的根-茎分配对于最大化整个植物的生长速率并不是必需的。不同的分配方式可以实现相似的生长速率。分配的变化不能维持或恢复较高的整个植物的生长速率。根和茎不必紧密协调，但可以半自主地运作，因为它们的模块化结构允许这样做。这些发现质疑了普遍存在的植物根-茎分配反应的一般解释，即“最优分配理论”（OPT）的合理性。局部分配模型而不是 OPT 可以解释个体间根-茎权衡变化的起源、生物量在全球和生态系统尺度上的分配，并为作物育种中的分配可塑性选择提供信息。
