A Distorted Circadian Clock Causes Early Flowering and Temperature-Dependent Variation in Spike Development in the Eps-3Am Mutant of Einkorn Wheat
A Distorted Circadian Clock Causes Early Flowering and Temperature-Dependent Variation in Spike Development in the Eps-3Am Mutant of Einkorn Wheat
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DOI：
10.1534/genetics.113.158444
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发表时间：
2014-04-01
期刊：
影响因子：
3.3
通讯作者：
Schnurbusch, Thorsten
中科院分区：
文献类型：
--
作者：
Gawronski, Piotr;Ariyadasa, Ruvini;Schnurbusch, Thorsten
有活力的生物钟帮助生物体使其发育与每日和季节性变化同步，从而从进化适应性以及农业角度提供优势。一种高分辨率定位方法结合突变体分析揭示了拟南芥LUX ARRHYTHMO/PHYTOCLOCK 1（LUX/PCL1）在谷类中的直系同源基因是一粒小麦（Triticum monococcum L.）中本身早熟3（Eps - 3A(m)）位点的一个有希望的候选基因。利用延迟荧光测量表明，含有Eps - 3A(m)的一粒小麦品种KT3 - 5具有紊乱的生物钟。随后通过对核心和输出生物钟基因进行时间进程研究证实了这一假设，该研究显示在恒定环境条件（即恒定光照和温度）下，KT3 - 5中存在无节律的转录模式。还证明了野生型和突变体之间的小穗数差异对温度敏感，在25℃时差异可忽略不计。这些观察结果使我们提出，紊乱的生物钟是早花以及穗大小和小穗数变化的原因，并且LUX功能失调在较温暖的气候中可能具有中性甚至积极的影响。为了检验后一个假设，我们确定了一系列小麦种质中LUX的序列变异。我们观察到来自较温暖气候的品种中LUX序列具有更高的变异，并且在早花的中国硬粒小麦品种“清华559号”中存在一种独特的读框内突变。我们的结果强调了温带谷类生物钟作为适应新环境的一个有希望的靶点的重要性。
Viable circadian clocks help organisms to synchronize their development with daily and seasonal changes, thereby providing both evolutionary fitness and advantage from an agricultural perspective. A high-resolution mapping approach combined with mutant analysis revealed a cereal ortholog of Arabidopsis thaliana LUX ARRHYTHMO/PHYTOCLOCK 1 (LUX/PCL1) as a promising candidate for the earliness per se 3 (Eps-3A(m)) locus in einkorn wheat (Triticum monococcum L.). Using delayed fluorescence measurements it was shown that Eps-3A(m) containing einkorn wheat accession KT3-5 had a distorted circadian clock. The hypothesis was subsequently confirmed by performing a time course study on central and output circadian clock genes, which showed arrhythmic transcript patterns in KT3-5 under constant ambient conditions, i.e., constant light and temperature. It was also demonstrated that variation in spikelet number between wild-type and mutants is sensitive to temperature, becoming negligible at 25 degrees. These observations lead us to propose that the distorted clock is causative for both early flowering and variation in spike size and spikelet number, and that having a dysfunctional LUX could have neutral, or even positive, effects in warmer climates. To test the latter hypothesis we ascertained sequence variation of LUX in a range of wheat germplasm. We observed a higher variation in the LUX sequence among accessions coming from the warmer climate and a unique in-frame mutation in early-flowering Chinese T. turgidum cultivar 'Tsing Hua no. 559.' Our results emphasize the importance of the circadian clock in temperate cereals as a promising target for adaptation to new environments.