Jayawardena Dileepa M, Heckathorn Scott A, Bista Deepesh R, Mishra Sasmita, Boldt Jennifer K, Krause Charles R
Department of Environmental Sciences, University of Toledo, Toledo, OH, USA.
Agricultural Research Service, United States Department of Agriculture, Toledo, OH, USA.
Physiol Plant. 2017 Mar;159(3):354-365. doi: 10.1111/ppl.12532. Epub 2017 Jan 19.
Atmospheric CO enrichment is expected to often benefit plant growth, despite causing global warming and nitrogen (N) dilution in plants. Most plants primarily procure N as inorganic nitrate (NO ) or ammonium (NH ), using membrane-localized transport proteins in roots, which are key targets for improving N use. Although interactive effects of elevated CO , chronic warming and N form on N relations are expected, these have not been studied. In this study, tomato (Solanum lycopersicum) plants were grown at two levels of CO (400 or 700 ppm) and two temperature regimes (30 or 37°C), with NO or NH as the N source. Elevated CO plus chronic warming severely inhibited plant growth, regardless of N form, while individually they had smaller effects on growth. Although %N in roots was similar among all treatments, elevated CO plus warming decreased (1) N-uptake rate by roots, (2) total protein concentration in roots, indicating an inhibition of N assimilation and (3) shoot %N, indicating a potential inhibition of N translocation from roots to shoots. Under elevated CO plus warming, reduced NO -uptake rate per g root was correlated with a decrease in the concentration of NO -uptake proteins per g root, reduced NH uptake was correlated with decreased activity of NH -uptake proteins and reduced N assimilation was correlated with decreased concentration of N-assimilatory proteins. These results indicate that elevated CO and chronic warming can act synergistically to decrease plant N uptake and assimilation; hence, future global warming may decrease both plant growth and food quality (%N).
尽管大气中二氧化碳浓度升高会导致全球变暖以及植物体内氮素稀释，但预计它通常会促进植物生长。大多数植物主要通过根中膜定位转运蛋白获取无机硝酸盐（NO₃⁻）或铵（NH₄⁺）形式的氮，这些转运蛋白是提高氮利用效率的关键靶点。尽管预计二氧化碳浓度升高、长期变暖以及氮形态之间会对氮关系产生交互作用，但尚未对此进行研究。在本研究中，番茄（Solanum lycopersicum）植株在两种二氧化碳水平（400或700 ppm）和两种温度条件（30或37°C）下生长，分别以NO₃⁻或NH₄⁺作为氮源。无论氮形态如何，二氧化碳浓度升高加上长期变暖会严重抑制植物生长，而单独的二氧化碳浓度升高或长期变暖对生长的影响较小。尽管所有处理下根中的氮含量相似，但二氧化碳浓度升高加上变暖降低了：（1）根的氮吸收速率；（2）根中的总蛋白浓度，表明氮同化受到抑制；（3）地上部氮含量，表明根向地上部的氮转运可能受到抑制。在二氧化碳浓度升高加上变暖的条件下，每克根的NO₃⁻吸收速率降低与每克根中NO₃⁻吸收蛋白浓度降低相关，NH₄⁺吸收减少与NH₄⁺吸收蛋白活性降低相关，氮同化减少与氮同化蛋白浓度降低相关。这些结果表明，二氧化碳浓度升高和长期变暖可协同作用降低植物对氮的吸收和同化；因此，未来全球变暖可能会降低植物生长和食物质量（氮含量）。
