拟南芥生态型适应不同日长的本地栖息地,温度,和降水在光强和叶片温度的七个组合下进行实验生长,以评估其在叶面结构和功能中的适应性表型可塑性。当植物在400μmol光子m-2s-1和25°C的中等条件下发育时,生态型之间没有差异。然而,为了应对更极端的光线或温度状况,在栖息地中进化的生态型在日长或温度或降水水平变化的幅度上都存在明显差异,表现出光合作用和蒸腾作用的明显调整。以及支持这些功能的解剖学特征。具体来说,当在极端光强度(100对1000μmol光子m-2s-1)或温度(8°C对35°C)下生长时,来自生长季节的日长和温度范围最大的地点的生态型在与光合作用相关的功能和结构特征上表现出最大的差异(氧气释放的光和CO2饱和能力,单位面积或厚度的叶片干重,每个小静脉的韧皮部细胞,和二氧化碳吸收的水利用效率)。另一方面,来自降水量最低的生境的生态型在与水运输和损失相关的特征中显示出最大的可塑性(脉密度,叶面小脉中水与糖导管的比率,和蒸腾速率)。尽管存在这些差异,在所有生态型和生长条件下都存在共同的结构-功能关系,具有显著的积极意义,光合能力(10至110µmolO2m-2s-1)与单位面积叶片干质量(10至75gm-2)之间的线性相关(i),叶片厚度(从170到500μm),和碳水化合物出口基础设施(每个小脉6到14个筛子,每个筛子元件的横截面面积为2.5至8µm2,和16至82µm2每小脉的筛子横截面积);(ii)蒸腾速率(从1至17mmolH2Om-2s-1)和水运基础设施之间(每小脉3.5至8个气管元素,从13.5到28µm2的横截面积,和每个小静脉的气管元素的横截面面积从55到200µm2);(iii)蒸腾失水与CO2固定的比率(从0.2到0.7molH2O到mmol-1CO2)与小静脉中水与糖导管的比率之间(从0.4到1.1气管到筛子元素,从4到6µm2的砂眼到筛子的横截面面积,和2至6µm2的气管元素横截面积至每个小静脉的筛子元素);(iv)在糖导管和糖负载细胞之间;(v)在导水和导糖细胞之间。此外,对于在热-热与冷温度下实验生长的所有生态型,水导管与糖导管的比例更高。因此,对生长环境的发育适应包括生态型依赖的叶面结构和功能调整,从而产生多种常见的结构和功能关系。
Arabidopsis thaliana ecotypes adapted to native habitats with different daylengths, temperatures, and precipitation were grown experimentally under seven combinations of light intensity and leaf temperature to assess their acclimatory phenotypic plasticity in foliar structure and function. There were no differences among ecotypes when plants developed under moderate conditions of 400 µmol photons m-2 s-1 and 25 °C. However, in response to more extreme light or temperature regimes, ecotypes that evolved in habitats with pronounced differences in either the magnitude of changes in daylength or temperature or in precipitation level exhibited pronounced adjustments in photosynthesis and transpiration, as well as anatomical traits supporting these functions. Specifically, when grown under extremes of light intensity (100 versus 1000 µmol photons m-2 s-1) or temperature (8 °C versus 35 °C), ecotypes from sites with the greatest range of daylengths and temperature over the growing season exhibited the greatest differences in functional and structural features related to photosynthesis (light- and CO2-saturated capacity of oxygen evolution, leaf dry mass per area or thickness, phloem cells per minor vein, and water-use efficiency of CO2 uptake). On the other hand, the ecotype from the habitat with the lowest precipitation showed the greatest plasticity in features related to water transport and loss (vein density, ratio of water to sugar conduits in foliar minor veins, and transpiration rate). Despite these differences, common structure-function relationships existed across all ecotypes and growth conditions, with significant positive, linear correlations (i) between photosynthetic capacity (ranging from 10 to 110 µmol O2 m-2 s-1) and leaf dry mass per area (from 10 to 75 g m-2), leaf thickness (from 170 to 500 µm), and carbohydrate-export infrastructure (from 6 to 14 sieve elements per minor vein, from 2.5 to 8 µm2 cross-sectional area per sieve element, and from 16 to 82 µm2 cross-sectional area of sieve elements per minor vein); (ii) between transpiration rate (from 1 to 17 mmol H2O m-2 s-1) and water-transport infrastructure (from 3.5 to 8 tracheary elements per minor vein, from 13.5 to 28 µm2 cross-sectional area per tracheary element, and from 55 to 200 µm2 cross-sectional area of tracheary elements per minor vein); (iii) between the ratio of transpirational water loss to CO2 fixation (from 0.2 to 0.7 mol H2O to mmol-1 CO2) and the ratio of water to sugar conduits in minor veins (from 0.4 to 1.1 tracheary to sieve elements, from 4 to 6 µm2 cross-sectional area of tracheary to sieve elements, and from 2 to 6 µm2 cross-sectional area of tracheary elements to sieve elements per minor vein); (iv) between sugar conduits and sugar-loading cells; and (v) between water conducting and sugar conducting cells. Additionally, the proportion of water conduits to sugar conduits was greater for all ecotypes grown experimentally under warm-to-hot versus cold temperature. Thus, developmental acclimation to the growth environment included ecotype-dependent foliar structural and functional adjustments resulting in multiple common structural and functional relationships.