Yang Jingli, Song Jinnan, Jeong Byoung Ryong
Shandong Provincial University Laboratory for Protected Horticulture, Weifang University of Science and Technology, Shouguang 262700, China.
Department of Horticulture, Division of Applied Life Science (BK21 Four), Graduate School, Gyeongsang National University, Jinju 52828, Republic of Korea.
Plants (Basel). 2024 Jan 26;13(3):375. doi: 10.3390/plants13030375.
The strawberry ( Duch.) "Sulhyang" is a typical seasonal flowering (SF) strawberry that produces flower buds in day lengths shorter than a critical limit (variable, but often defined as <12 h). There is a trade-off between photoperiod-controlled flowering and gibberellin (GA) signaling pathway-mediated runnering. Some related genes (such as , , , and ) participating in light signaling and circadian rhythm in plants are altered under blue light (BL). Sugars for flowering and runnering are mainly produced by photosynthetic carbon assimilation. The intensity of light could affect photosynthesis, thereby regulating flowering and runnering. Here, we investigated the effect of the intensity of supplemental blue light (S-BL) or night-interrupting blue light (NI-BL) in photoperiodic flowering and runnering regulation by applying 4 h of S-BL or NI-BL with either 0, 10, 20, 30, or 40 μmol·m·s photosynthetic photon flux density (PPFD) in a 10 h short-day (SD10) (SD10 + S-BL4 or + NI-BL4 (0, 10, 20, 30, or 40)) or 14 h long-day (LD14) conditions (LD14 + S-BL4 or + NI-BL4 (0, 10, 20, 30, or 40)). Approximately 45 days after the photoperiodic light treatment, generally, whether S-BL or NI-BL, BL (20) was the most promotive in runnering, leading to more runners in both the LD and SD conditions. For flowering, except the treatment LD14 + S-BL, BL (20) was still the key light, either from BL (20) or BL (40), promoting flowering, especially when BL acted as the night-interrupting light, regardless of the photoperiod. At the harvest stage, larger numbers of inflorescences and runners were observed in the LD14 + NI-BL4 treatment, and the most were observed in the LD14 + NI-BL (20). Moreover, the SD10 + NI-BL4 was slightly inferior to the LD14 + NI-BL4 in increasing the numbers of inflorescences and runners, but it caused earlier flowering. Additionally, the circadian rhythm expression of flowering-related genes was affected differently by the S-BL and NI-BL. After the application of BL in LD conditions, the expression of an LD-specific floral activator was stimulated, while that of a flowering suppressor was inhibited, resetting the balance of expression between these two opposite flowering regulators. The SD runnering was caused by BL in non-runnering SD conditions associated with the stimulation of two key genes that regulate runner formation in the GA pathway, and . In addition, the positive effects of BL on enhancing photosynthesis and carbohydrate production also provided an abundant energy supply for the flowering and runnering processes.
草莓（Fragaria × ananassa Duch.）“苏香”是一种典型的季节性开花（SF）草莓，其在日长小于临界值（可变，但通常定义为<12小时）时产生花芽。光周期控制的开花与赤霉素（GA）信号通路介导的匍匐茎形成之间存在权衡。一些参与植物光信号和昼夜节律的相关基因（如PHYB、CRY1、CRY2和CO）在蓝光（BL）下会发生改变。用于开花和匍匐茎形成的糖分主要通过光合碳同化产生。光照强度会影响光合作用，从而调节开花和匍匐茎形成。在此，我们通过在10小时短日照（SD10）（SD10 + S - BL4或 + NI - BL4（0、10、20、30或40））或14小时长日照（LD14）条件（LD14 + S - BL4或 + NI - BL4（0、10、20、30或40））下施加4小时光合光子通量密度（PPFD）为0、10、20、30或40 μmol·m⁻²·s⁻¹的补充蓝光（S - BL）或夜间中断蓝光（NI - BL），研究了补充蓝光（S - BL）或夜间中断蓝光（NI - BL）强度对光周期开花和匍匐茎形成调节的影响。在光周期光照处理约45天后，一般来说，无论是S - BL还是NI - BL，蓝光（20）对匍匐茎形成的促进作用最大，在长日照和短日照条件下都会产生更多的匍匐茎。对于开花，除了LD14 + S - BL处理外，蓝光（20）仍然是关键光照，无论是蓝光（20）还是蓝光（40），都能促进开花，特别是当蓝光作为夜间中断光时，无论光周期如何。在收获期，在LD14 + NI - BL4处理中观察到更多的花序和匍匐茎数，在LD14 + NI - BL（20）中观察到的最多。此外，SD10 + NI - BL4在增加花序和匍匐茎数方面略逊于LD14 + NI - BL4，但它导致更早开花。此外，开花相关基因的昼夜节律表达受S - BL和NI - BL的影响不同。在长日照条件下施加蓝光后，长日照特异性花激活因子FT的表达受到刺激，而开花抑制因子FLC的表达受到抑制，重新设定了这两种相反开花调节因子之间的表达平衡。短日照条件下的匍匐茎形成是由非匍匐茎短日照条件下的蓝光引起的，这与GA途径中两个调节匍匐茎形成的关键基因GA20ox和GA3ox的刺激有关。此外，蓝光对增强光合作用和碳水化合物生产的积极作用也为开花和匍匐茎形成过程提供了充足的能量供应。
