Palma Carolina Falcato Fialho, Castro-Alves Victor, Morales Luis Orlando, Rosenqvist Eva, Ottosen Carl-Otto, Strid Åke
Department of Food Science, Plant, Food & Climate, Aarhus University, Aarhus, Denmark.
School of Science and Technology, Örebro Life Science Centre, Örebro University, Örebro, Sweden.
Front Plant Sci. 2021 Jan 5;11:610011. doi: 10.3389/fpls.2020.610011. eCollection 2020.
Ultraviolet B (UV-B) (280-315 nm) and ultraviolet A (UV-A) (315-400 nm) radiation comprise small portions of the solar radiation but regulate many aspects of plant development, physiology and metabolism. Until now, how plants respond to UV-B in the presence of different light qualities is poorly understood. This study aimed to assess the effects of a low UV-B dose (0.912 ± 0.074 kJ m day, at a 6 h daily UV exposure) in combination with four light treatments (blue, green, red and broadband white at 210 μmol m s Photosynthetically active radiation [PAR]) on morphological and physiological responses of cucumber ( cv. "Lausanna RZ F1"). We explored the effects of light quality backgrounds on plant morphology, leaf gas exchange, chlorophyll fluorescence, epidermal pigment accumulation, and on acclimation ability to saturating light intensity. Our results showed that supplementary UV-B significantly decreased biomass accumulation in the presence of broad band white, blue and green light, but not under red light. UV-B also reduced the photosynthetic efficiency of CO fixation (α) when combined with blue light. These plants, despite showing high accumulation of anthocyanins, were unable to cope with saturating light conditions. No significant effects of UV-B in combination with green light were observed for gas exchange and chlorophyll fluorescence parameters, but supplementary UV-B significantly increased chlorophyll and flavonol contents in the leaf epidermis. Plants grown under red light and UV-B significantly increased maximum photosynthetic rate and dark respiration compared to pure red light. Additionally, red and UV-B treated plants exposed to saturating light intensity showed higher quantum yield of photosystem II (PSII), fraction of open PSII centres and electron transport rate and showed no effect on the apparent maximum quantum efficiency of PSII photochemistry (F/F) or non-photochemical quenching, in contrast to solely red-light conditions. These findings provide new insights into how plants respond to UV-B radiation in the presence of different light spectra.
紫外线B（UV-B）（280 - 315纳米）和紫外线A（UV-A）（315 - 400纳米）辐射虽然只占太阳辐射的一小部分，但却能调控植物发育、生理和代谢的多个方面。到目前为止，人们对植物在不同光质条件下如何响应UV-B的了解还很少。本研究旨在评估低剂量UV-B（每天6小时UV照射下为0.912±0.074千焦·平方米·天）与四种光处理（蓝光、绿光、红光以及光合有效辐射[PAR]为210微摩尔·平方米·秒的宽带白光）相结合对黄瓜（品种“Lausanna RZ F1”）形态和生理响应的影响。我们探究了光质背景对植物形态、叶片气体交换、叶绿素荧光、表皮色素积累以及对饱和光强适应能力的影响。我们的结果表明，在宽带白光、蓝光和绿光存在的情况下，补充UV-B显著降低了生物量积累，但在红光下则没有。UV-B与蓝光结合时还降低了CO固定的光合效率（α）。这些植物尽管花青素积累量很高，但却无法应对饱和光照条件。对于气体交换和叶绿素荧光参数，未观察到UV-B与绿光结合有显著影响，但补充UV-B显著增加了叶片表皮中的叶绿素和黄酮醇含量。与纯红光相比，在红光和UV-B条件下生长的植物显著提高了最大光合速率和暗呼吸。此外，与仅在红光条件下相比，经红光和UV-B处理且暴露于饱和光强的植物显示出更高的光系统II（PSII）量子产率、开放PSII中心比例和电子传递速率，并且对PSII光化学的表观最大量子效率（F/F）或非光化学猝灭没有影响。这些发现为植物在不同光谱条件下如何响应UV-B辐射提供了新的见解。
