Wendell Micael, Ripel Linda, Lee YeonKyeong, Rognli Odd Arne, Torre Sissel, Olsen Jorunn E
Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, Norway.
Department of Plant Science and Research Institute for Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul, South Korea.
Plant Cell Physiol. 2017 Mar 1;58(3):466-477. doi: 10.1093/pcp/pcw221.
Thermoperiodism is defined as the ability to discriminate between day temperature (DT) and night temperature (NT). Our aim was to shed light on the mechanistic basis of thermoperiodic floral induction with acceleration under lower DT than NT compared with other DT-NT combinations at the same average daily temperature (ADT), a response exploited in temperate area greenhouses. Arabidopsis thaliana floral pathway mutants and a lhy circadian clock mutant as well as the expression of floral integrators and LHY (LATE ELONGATED HYPOCOTYL) were studied under different DT-NT combinations, all at the same ADT. We show that acceleration of floral induction under lower DT than NT is linked to increased FT expression early during the day and generally increased LFY expression preceding visible flower buds, compared with higher DT than NT or equal DT and NT. Consistent with FLOWERING LOCUS T (FT) action through LEAFY (LFY), time to floral transition in ft-1 and lfy-1 was similar under all treatments, in contrast to the situation for soc1-1, which behaved like the wild type (WT). The lhy-21 mutants did not discriminate between opposite DT-NT combinations, whereas LHY expression in the WT differed in these temperature regimes. This might suggest that LHY plays a role in thermoperiodic control of floral induction. We conclude that thermoperiodic control of floral transition is associated with modulation of the diurnal expression patterns of FT, with timing of temperature alteration being important rather than ADT.
温周期现象被定义为区分日温（DT）和夜温（NT）的能力。我们的目标是阐明在相同日均温度（ADT）下，与其他日温-夜温组合相比，在较低日温低于夜温时加速温周期花诱导的机制基础，这一现象在温带地区温室中得到应用。在相同的ADT下，研究了拟南芥花途径突变体、一个lhy生物钟突变体以及花整合因子和LHY（晚伸长下胚轴）在不同日温-夜温组合下的表达情况。我们发现，与日温高于夜温或日温与夜温相等的情况相比，日温低于夜温时花诱导的加速与白天早期FT表达增加以及在可见花芽出现之前LFY表达普遍增加有关。与通过LEAFY（LFY）起作用的开花位点T（FT）一致，在所有处理下，ft-1和lfy-1中花转变的时间相似，这与soc1-1的情况相反，soc1-1表现得像野生型（WT）。lhy-21突变体无法区分相反的日温-夜温组合，而野生型中的LHY表达在这些温度条件下有所不同。这可能表明LHY在花诱导的温周期控制中起作用。我们得出结论，花转变的温周期控制与FT昼夜表达模式的调节有关，温度变化的时间很重要，而不是ADT。
