Zunzunegui María, Díaz-Barradas Mari Cruz, Jáuregui Juan, Rodríguez Herminia, Álvarez-Cansino Leonor
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
Plant Physiol Biochem. 2016 May;102:80-91. doi: 10.1016/j.plaphy.2016.02.004. Epub 2016 Feb 11.
Semi-arid plant species cope with excess of solar radiation with morphological and physiological adaptations that assure their survival when other abiotic stressors interact. At the leaf level, sun and shade plants may differ in the set of traits that regulate environmental stressors. Here, we evaluated if leaf-level physiological seasonal response of Mediterranean scrub species (Myrtus communis, Halimium halimifolium, Rosmarinus officinalis, and Cistus salvifolius) depended on light availability conditions. We aimed to determine which of these responses prevailed independently of the marked seasonality of Mediterranean climate, to define a leaf-level strategy in the scrub community. Thirty six leaf response variables - involving gas exchange, water status, photosystem II photochemical efficiency, photosynthetic pigments and leaf structure - were seasonally measured in sun exposed and shaded plants under field conditions. Physiological responses showed a common pattern throughout the year, in spite of the marked seasonality of the Mediterranean climate and of species-specific differences in the response to light intensity. Variables related to light use, CO2 assimilation, leaf pigment content, and LMA (leaf mass area) presented differences that were consistent throughout the year, although autumn was the season with greater contrast between sun and shade plants. Our data suggest that in Mediterranean scrub shade plants the lutein pool could have an important role in the photoprotection of the photosynthetic tissues. There was a negative linear correlation between the ratio lutein/total chlorophylls and the majority of leaf level variables. The combined effect of abiotic stress factors (light and drought or light and cold) was variable-specific, in some cases enhancing differences between sun and shade plants, while in others leading to unified strategies in all scrub species.
半干旱植物物种通过形态和生理适应来应对过量的太阳辐射，这些适应确保了它们在其他非生物胁迫因素相互作用时的生存。在叶片层面，阳生植物和阴生植物在调节环境胁迫因素的一系列性状上可能存在差异。在这里，我们评估了地中海灌丛物种（香桃木、绵毛半日花、迷迭香和岩蔷薇）的叶片水平生理季节性响应是否依赖于光照条件。我们旨在确定这些响应中哪些在不受地中海气候明显季节性影响的情况下占主导地位，以便在地中海灌丛群落中定义一种叶片水平的策略。在田间条件下，对暴露在阳光下和遮荫的植物季节性地测量了36个叶片响应变量，这些变量涉及气体交换、水分状况、光系统II光化学效率、光合色素和叶片结构。尽管地中海气候有明显的季节性，且物种对光照强度的响应存在特异性差异，但生理响应全年呈现出一种共同模式。与光利用、二氧化碳同化、叶片色素含量和叶面积质量（LMA）相关的变量全年都存在差异，尽管秋季是阳生植物和阴生植物之间差异更大的季节。我们的数据表明，在地中海灌丛的阴生植物中，叶黄素库可能在光合组织的光保护中发挥重要作用。叶黄素/总叶绿素的比率与大多数叶片水平变量之间存在负线性相关。非生物胁迫因素（光照和干旱或光照和寒冷）的综合作用因变量而异，在某些情况下会增强阳生植物和阴生植物之间的差异，而在其他情况下则会导致所有灌丛物种采取统一的策略。
