Zha Lingyan, Liu Wenke, Yang Qichang, Zhang Yubin, Zhou Chengbo, Shao Mingjie
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.
Key Laboratory of Energy Conservation and Waste Management of Agricultural Structures, Ministry of Agriculture and Rural Affairs, Beijing, China.
Front Plant Sci. 2020 May 29;11:704. doi: 10.3389/fpls.2020.00704. eCollection 2020.
Ascorbate (AsA), an antioxidant that cannot be synthesized and stored by the human body, plays an essential role in the proper functioning of both plants and humans. With the goal of increasing the AsA level in lettuce, the effects of different ratios of red (R) to blue (B) light (75R:25B, 50R:50B, and 25R:75B) on AsA pool sizes as well as the transcript levels and activities of key enzymes involved in AsA metabolism were constantly monitored for 12 days under continuous light (200 μmol⋅m⋅s) from LEDs. The results showed that lettuce biomass was positively correlated with the ratio of red light, while the AsA pool size had a positive correlation with the ratio of blue light during the whole experiment. The 25R:75B treatment increased the expression of genes involved in AsA biosynthesis (, , , , ) and regeneration (, , , and ) on day 3 but only significantly elevated the activities of enzymes involved in AsA regeneration (APX, MDHAR, DHAR, and GR) subsequently. AsA regeneration enzymes (MDHAR, DHAR and GR) had greater correlations with the AsA level than the AsA synthesis enzyme (GLDH). Thus, it is concluded that a high ratio of blue light elevated the AsA level mainly by promoting AsA regeneration rather than biosynthesis. Taken together, altering the red:blue ratio of continuous light from high to low before harvest is recommended for lettuce cultivation to achieve both high yield and high quality.
抗坏血酸（AsA）是一种人体无法合成和储存的抗氧化剂，在植物和人体的正常功能中都起着至关重要的作用。为了提高生菜中的AsA含量，在来自发光二极管的持续光照（200 μmol⋅m⋅s）下，连续12天持续监测不同红（R）蓝光比例（75R:25B、50R:50B和25R:75B）对AsA库大小以及AsA代谢相关关键酶的转录水平和活性的影响。结果表明，在整个实验过程中，生菜生物量与红光比例呈正相关，而AsA库大小与蓝光比例呈正相关。25R:75B处理在第3天增加了参与AsA生物合成（、、、和）和再生（、、、和）的基因表达，但随后仅显著提高了参与AsA再生的酶（APX、MDHAR、DHAR和GR）的活性。与AsA合成酶（GLDH）相比，AsA再生酶（MDHAR、DHAR和GR）与AsA水平的相关性更大。因此，得出结论，高比例蓝光主要通过促进AsA再生而非生物合成来提高AsA水平。综上所述，建议在收获前将持续光照的红:蓝比例从高到低进行改变，以实现生菜的高产和高品质栽培。
