Centre for Agricultural Research, Agricultural Institute, Eötvös Loránd Research Network, H-2462 Martonvásár, Hungary.
Department of Environmental Sustainability, Festetics Doctoral School, IES, Hungarian University of Agriculture and Life Sciences, H-8360 Keszthely, Hungary.
Biomolecules. 2021 Mar 17;11(3):450. doi: 10.3390/biom11030450.
Cold acclimation, the necessary prerequisite for promotion of freezing tolerance, is affected by both low temperature and enhanced far-red/red light (FR/R) ratio. The impact of FR supplementation to white light, created by artificial LED light sources, on the hormone levels, metabolism, and expression of the key hormone metabolism-related genes was determined in winter barley at moderate (15 °C) and low (5 °C) temperature. FR-enhanced freezing tolerance at 15 °C was associated with promotion of abscisic acid (ABA) levels, and accompanied by a moderate increase in indole-3-acetic acid (IAA) and -zeatin levels. The most prominent impact on the plants' freezing tolerance was found after FR pre-treatment at 15 °C (for 10 days) followed by cold treatment at FR supplementation (7 days). The response of ABA was diminished in comparison with white light treatment, probably due to the elevation of stress tolerance during FR pre-treatment. Jasmonic acid (JA) and salicylic acid (SA) were transiently reduced. When the plants were exposed directly to a combination of cold (5 °C) and FR supplementation, ABA increase was higher than in white light, and was associated with enhanced elevation of JA and, in the longer term (after 7 days), with IAA and -zeatin increase, which indicates a stronger stress response and better acclimation. Cold hardening was more efficient when FR light was applied in the early developmental stage of the barley plants (three-leaf stage, 18 days), rather than in later stages (28-days). The dynamics of the phytohormone changes are well supported by the expression profiles of the key hormone metabolism-related genes. This series of treatments serves as evidence for the close relationship between plant hormones, light quality, and low temperature at the beginning of cold acclimation. Besides the timing of the FR treatments, plant age also represents a key factor during light spectrum-dependent cold acclimation.
冷驯化是提高抗冻性的必要前提，它受低温和增强的远红光/红光（FR/R）比例的影响。在中等（15°C）和低（5°C）温度下，通过人工 LED 光源产生的 FR 增强白光，确定了 FR 对冬季大麦中激素水平、代谢和关键激素代谢相关基因表达的影响。在 15°C 时，FR 增强的抗冻性与促进脱落酸（ABA）水平有关，并伴随着吲哚-3-乙酸（IAA）和玉米素水平的适度增加。在 FR 预处理 15°C（10 天）后再进行冷处理 FR 补充（7 天）时，对植物抗冻性的影响最为显著。与白光处理相比，ABA 的响应减弱，这可能是由于 FR 预处理期间提高了应激耐受性。茉莉酸（JA）和水杨酸（SA）短暂减少。当植物直接暴露于冷（5°C）和 FR 补充的组合时，ABA 的增加高于白光，并且与 JA 的增强升高有关，并且在较长时间（7 天后）与 IAA 和玉米素升高有关，这表明应激反应更强，适应能力更好。当 FR 光在大麦植物的早期发育阶段（三叶期，18 天）应用时，冷驯化的效率更高，而不是在后期（28 天）。激素代谢相关基因的表达谱很好地支持了植物激素变化的动态。这一系列处理为植物激素、光质和低温在冷驯化初期之间的密切关系提供了证据。除了 FR 处理的时间外，植物年龄也是光质依赖冷驯化过程中的关键因素。
