Temperature is an environmental cue that entrains the circadian clock, adapting it to local thermal and photoperiodic conditions that characterize different geographic regions. Circadian clock thermal adaptation in leafy vegetables such as Chinese cabbage (Brassica rapa ssp. pekinensis) is poorly understood but essential to sustain and increase vegetable production under changing climates. We investigated circadian rhythmicity in natural Chinese cabbage accessions grown at 14, 20, and 28 °C. The circadian period was significantly shorter at 20 °C than at either 14 or 28 °C, and the responses to increasing temperature and temperature compensation (Q10) were associated with population structure. Genome-wide association studies mapping identified variation responsible for temperature compensation as measured by Q10 value for temperature increase from 20 to 28 °C. Haplotype analysis indicated that B. rapa EARLY FLOWERING 3 H1 Allele (BrELF3H1) conferred a significantly higher Q10 value at 20 to 28 °C than BrELF3H2. Co-segregation analyses of an F2 population derived from a BrELF3H1 × BrELF3H2 cross revealed that variation among BrELF3 alleles determined variation in the circadian period of Chinese cabbage at 20 °C. However, their differential impact on circadian oscillation was attenuated at 28 °C. Transgenic complementation in Arabidopsis thaliana elf3-8 mutants validated the involvement of BrELF3 in the circadian clock response to thermal cues, with BrELF3H1 conferring a higher Q10 value than BrELF3 H2 at 20 to 28 °C. Thus, BrELF3 is critical to the circadian clock response to ambient temperature in Chinese cabbage. These findings have clear implications for breeding new varieties with enhanced resilience to extreme temperatures.

中文翻译：

---

早花 3 个等位基因影响大白菜生物钟的温度反应性


温度是昼夜节律时钟的环境线索，使其适应表征不同地理区域的局部热和光周期条件。人们对大白菜 （Brassica rapa ssp. pekinensis） 等叶类蔬菜的生物钟热适应知之甚少，但对于在不断变化的气候下维持和增加蔬菜产量至关重要。我们研究了在 14 、 20 和 28 °C 下生长的天然大白菜种质的昼夜节律。 20 °C 的昼夜节律周期显著短于 14 °C 或 28 °C，并且对温度升高和温度补偿 （Q10） 的响应与种群结构相关。全基因组关联研究绘制确定了负责温度补偿的变异，通过温度从 20 °C 升高到 28 °C 的 Q10 值来测量。 单倍型分析表明，在 20 至 28 °C 时，白菜早花 3 H1 等位基因 （BrELF3H1） 赋予 Q10 值显著高于 BrELF3H2。对 BrELF3H1 × BrELF3H2 杂交来源的 F2 群体进行共分离分析，结果显示 BrELF3 等位基因之间的变异决定了大白菜在 20 °C 下昼夜节律的变化。 然而，它们对昼夜节律振荡的不同影响在 28 °C 时减弱。 拟南芥 elf3-8 突变体中的转基因互补验证了 BrELF3 参与生物钟对热线索的反应，BrELF3H1 在 20 至 28 °C 时赋予比 BrELF3 H2 更高的 Q10 值。 因此，BrELF3 对大白菜的生物钟对环境温度的响应至关重要。这些发现对培育具有更强极端温度适应能力的新品种具有明显的意义。