Plant Sciences Institute, Volcani Agricultural Research Organization (ARO), Bet Dagan, Israel.
Department of Life Sciences, Ben-Gurion University, Beer-Sheva, Israel.
Plant Cell Environ. 2019 Nov;42(11):3105-3120. doi: 10.1111/pce.13606. Epub 2019 Jul 30.
Temperature compensation, expressed as the ability to maintain clock characteristics (mainly period) in face of temperature changes, that is, robustness, is considered a key feature of circadian clock systems. In this study, we explore the genetic basis for lack of robustness, that is, plasticity, of circadian clock as reflected by photosynthesis rhythmicity. The clock rhythmicity of a new wild barley reciprocal doubled haploid population was analysed with a high temporal resolution of pulsed amplitude modulation of chlorophyll fluorescence under optimal (22°C) and high (32°C) temperature. This comparison between two environments pointed to the prevalence of clock acceleration under heat. Genotyping by sequencing of doubled haploid lines indicated a rich recombination landscape with minor fixation (less than 8%) for one of the parental alleles. Quantitative genetic analysis included genotype by environment interactions and binary-threshold models. Variation in the circadian rhythm plasticity phenotypes, expressed as change (delta) of period and amplitude under two temperatures, was associated with maternal organelle genome (the plasmotype), as well as with several nuclear loci. This first reported rhythmicity driven by nuclear loci and plasmotype with few identified variants, paves the way for studying impact of cytonuclear variations on clock robustness and on plant adaptation to changing environments.
温度补偿，表现为在温度变化下保持时钟特征（主要是周期）的能力，即稳健性，被认为是生物钟系统的关键特征。在这项研究中，我们探索了生物钟缺乏稳健性（即可塑性）的遗传基础，这种稳健性反映在光合作用的节律性上。利用叶绿素荧光脉冲幅度调制的高时间分辨率，对一个新的野生大麦正反交双单倍体群体的时钟节律性进行了分析，实验在最佳（22°C）和高温（32°C）条件下进行。这两种环境的比较表明，在高温下时钟加速普遍存在。通过测序对双单倍体系进行的基因型分析表明，重组景观丰富，两个亲本等位基因之一的固定率（小于 8%）较低。数量遗传分析包括基因型与环境互作和二元阈值模型。以两个温度下的周期和振幅变化（delta）表示的生物钟节律性可塑性表型的变化与母细胞器基因组（质体型）以及几个核基因座有关。这是第一个报道的由核基因座和质体型驱动的节律性，且只有少数已鉴定的变异，为研究胞质核变异对时钟稳健性和植物对环境变化的适应的影响铺平了道路。
