Burnett Angela C, Rogers Alistair, Rees Mark, Osborne Colin P
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
Plant Cell Environ. 2016 Nov;39(11):2460-2472. doi: 10.1111/pce.12801. Epub 2016 Sep 22.
Understanding how carbon source and sink strengths limit plant growth is a critical knowledge gap that hinders efforts to maximize crop yield. We investigated how differences in growth rate arise from source-sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO concentrations ([CO ]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO ] indicating that source strength was near maximal at current [CO ]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO ] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO ], and lower non-structural carbohydrate accumulation. Alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO ].
了解碳源和碳汇强度如何限制植物生长是一个关键的知识空白，阻碍了人们为实现作物产量最大化所做的努力。我们使用一个模型系统，比较了快速生长的驯化一年生大麦（Hordeum vulgare cv. NFC Tipple）和生长缓慢的野生多年生近缘种（Hordeum bulbosum），研究了源库限制如何导致生长速率的差异。通过在低于环境浓度和升高的二氧化碳浓度（[CO₂]）下种植植物来操纵源强度。通过测量相对生长速率、发育可塑性、光合作用以及主要碳和氮代谢物库来诊断源和库对营养生长的限制。一年生植物的生长受库限制，而多年生植物受源限制。一年生植物的相对生长速率和碳获取量较高，但光合作用对升高的[CO₂]反应较弱，这表明在当前[CO₂]浓度下源强度接近最大值。相比之下，多年生植物的光合速率和库发育对升高的[CO₂]反应强烈，表明存在显著的源限制。多年生植物通过高库可塑性避免了库限制：在升高的[CO₂]浓度下分蘖和根冠比显著增加，非结构性碳水化合物积累减少。在营养生长阶段缓解库限制对于在未来升高的[CO₂]浓度下使优良谷物生长最大化可能很重要。
