Hu Jing, Yang Qiu-Yun, Huang Wei, Zhang Shi-Bao, Hu Hong
Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China.
Planta. 2014 Sep;240(3):489-96. doi: 10.1007/s00425-014-2097-z. Epub 2014 Jun 7.
Modifications in leaf anatomy of tobacco plants induced greater leaf water transport capacity, meeting greater transpirational demands and acclimating to warmer temperatures with a higher vapor pressure deficit. Temperature is one of the most important environmental factors affecting photosynthesis and growth of plants. However, it is not clear how it may alter leaf hydraulic architecture. We grew plants of tobacco (Nicotiana tabacum) 'k326' in separate glasshouse rooms set to different day/night temperature conditions: low (LT 24/18 °C), medium (MT 28/22 °C), or high (HT 32/26 °C). After 40 days of such treatment, their leaf anatomies, leaf hydraulics, photosynthetic rates, and instantaneous water-use efficiency (WUEi) were measured. Compared with those under LT, plants exposed to HT or MT conditions had significantly higher values for minor vein density (MVD), stomatal density (SD), leaf area, leaf hydraulic conductance (K leaf), and light-saturated photosynthetic rate (A sat), but lower values for leaf water potential (ψ l) and WUEi. However, those parameters did not differ significantly between HT and MT conditions. Correlation analyses demonstrated that SD and K leaf increased in parallel with MVD. Moreover, greater SD and K leaf were partially associated with accelerated stomatal conductance. And then stomatal conductance was positively correlated with A sat. Therefore, under well-watered, fertilized conditions, when relative humidity was optimal, changes in leaf anatomy seemed to facilitate the hydraulic acclimation to higher temperatures, meeting greater transpirational demands and contributing to the maintenance of great photosynthetic rates. Because transpiration rate increased more with temperature than photosynthetic rate, WUEi reduced under warmer temperatures. Our results indicate that the modifications of leaf hydraulic architecture are important anatomical and physiological strategies for tobacco plants acclimating to warmer temperatures under a higher vapor pressure deficit.
烟草植株叶片解剖结构的改变使其叶片水分运输能力增强，能够满足更高的蒸腾需求，并适应更高水汽压亏缺下的温暖温度。温度是影响植物光合作用和生长的最重要环境因素之一。然而，尚不清楚它如何改变叶片水力结构。我们将烟草（Nicotiana tabacum）‘k326’种植在不同的温室房间中，设置不同的日/夜温度条件：低温（LT 24/18 °C）、中温（MT 28/22 °C）或高温（HT 32/26 °C）。经过40天的这种处理后，测量了它们的叶片解剖结构、叶片水力、光合速率和瞬时水分利用效率（WUEi）。与低温处理相比，处于高温或中温条件下的植株小叶脉密度（MVD）、气孔密度（SD）、叶面积、叶片水力导度（K叶）和光饱和光合速率（A sat）显著更高，但叶片水势（ψ l）和WUEi更低。然而，这些参数在高温和中温条件之间没有显著差异。相关性分析表明，SD和K叶与MVD平行增加。此外，更大的SD和K叶部分与气孔导度加快有关。然后气孔导度与A sat呈正相关。因此，在水分充足、施肥条件良好且相对湿度适宜的情况下，叶片解剖结构的变化似乎有助于水力适应更高温度，满足更高的蒸腾需求并有助于维持较高的光合速率。由于蒸腾速率随温度升高的幅度大于光合速率，在温暖温度下WUEi降低。我们的结果表明，叶片水力结构的改变是烟草植株在更高水汽压亏缺下适应温暖温度的重要解剖和生理策略。
