Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Sevilla, Spain.
Mediterranean Institute for Advanced Studies (CSIC-UIB) Mallorca, Balearic Islands, Spain.
Plant Biol (Stuttg). 2018 Nov;20(6):968-977. doi: 10.1111/plb.12875. Epub 2018 Aug 30.
The phenology of anthocyanin accumulation in leaves has been widely studied in perennial plants; several hypotheses have been proposed to explain their adaptive significance. Here, we explored the photoprotection hypothesis in Silene germana, a Mediterranean annual plant with late-spring/summer flowering. We analysed the temporal patterns of anthocyanin accumulation in photosynthetic calyces, leaves and stems and throughout the reproductive season, and their relationship with flower abortion, florivory and plant mortality due to drought. In addition, the flavonoid production and the photoinhibitory response were measured in a shading experiment. The whole plant becomes red at the end of the flowering and remains red until fruiting and senescence. Calyces were redder on the side with more sun exposition. Aborted flowers showed redder calyces than those of fruiting flowers. No effect of plant redness on florivory or plant mortality was found. The shading experiment showed a positive relationship between anthocyanin accumulation and intensity of solar radiation, but plants growing in absence of UV showed similar redness than full sunlight plants. Plants growing in natural shade lack anthocyanins but produced the same amount of non-anthocyanin flavonoids. Anthocyanic and non-anthocyanic plants showed similar photochemical efficiency (F /F ) after sun exposition, but in early morning, the former showed lower F /F values. Plants growing in full sunlight produced more fruits than those of natural shade plants. Whole-plant reddening during fruiting and senescence appears to be a property of S. germana. Our results suggest that anthocyanin accumulation depends on sunlight intensity, but non-anthocyanin flavonoids are produced constitutively.
叶片中花色素苷积累的物候学在多年生植物中得到了广泛研究；已经提出了几个假说来解释它们的适应意义。在这里，我们在春末/夏季开花的地中海一年生植物腺梗草莓（Silene germana）中探索了光保护假说。我们分析了光合作用花萼、叶片和茎部以及整个生殖季节中花色素苷积累的时间模式，以及它们与花朵败育、花食和干旱导致的植物死亡的关系。此外，在遮荫实验中测量了类黄酮的产生和光抑制反应。整个植物在开花结束时变成红色，并保持红色直到结果和衰老。花萼在阳光照射较多的一侧更红。败育的花朵的花萼比结果的花朵更红。没有发现植物变红对花食或植物死亡率的影响。遮荫实验表明，花色素苷积累与太阳辐射强度之间呈正相关，但在缺乏 UV 的情况下生长的植物比在全光照下生长的植物具有相似的红色。在自然遮荫下生长的植物缺乏花色素苷，但产生了与全光照植物相同数量的非花色素苷类黄酮。暴露在阳光下后，具有花色素苷和无花色素苷的植物表现出相似的光化学效率（F/F），但在清晨，前者表现出较低的 F/F 值。在全光照下生长的植物比在自然遮荫下生长的植物产生更多的果实。在结果和衰老期间整个植物变红似乎是 S. germana 的一个特性。我们的结果表明，花色素苷的积累取决于阳光强度，但非花色素苷类黄酮是组成性产生的。
