背景回顾：Plants have served as a preeminent study system for photoperiodism due to their propensity to flower in concordance with the seasons. 

提出问题：A nearly singular focus on understanding photoperiodic flowering has prevented the discovery of other photoperiod measuring systems necessary for vegetative health.

主要研究：Here, we use bioinformatics to identify photoperiod-induced genes in Arabidopsis. 

结果1-关键基因PP2-A13：We show that one, PP2-A13, is expressed exclusively in, and required for, plant fitness in short, winter-like photoperiods. 

结果2-PP2-A13独立于光周期开花机制：We create a real-time photoperiod reporter, using the PP2-A13 promoter driving luciferase, and show that photoperiodic regulation is independent of the canonical CO/FT mechanism for photoperiodic flowering. 

结果3-控制PP2-A13表达的分子机制：We then reveal that photosynthesis combines with circadian-clock-controlled starch production to regulate cellular sucrose levels to control photoperiodic expression of PP2-A13. 

结论：This work demonstrates the existence of a photoperiod measuring system housed in the metabolic network of plants that functions to control seasonal cellular health.

 摘 要 

植物因其能够季节性的开花，已成为研究光周期的主要系统。而由于大家的注意力都集中在植物光周期开花方面，对于营养生长所需的其它光周期感知系统并不清楚。本文中，作者利用生物信息学方法，鉴定了拟南芥中光周期诱导表达的基因。作者发现其中一个基因PP2-A13仅在像冬天一样的短的光周期下表达，并且对于植物在该条件下的适应性是必需的。作者利用PP2-A13基因的启动子驱动荧光素酶，建立了一个实时光周期报告系统，发现光周期调控独立于经典的光周期开花CO/FT机制。接着，作者发现光合作用与生物钟控制的淀粉合成一起，控制细胞的蔗糖水平，从而调控PP2-A13基因的光周期表达。本文的研究结果揭示了植物的代谢网络中存在一个光周期感知系统，作用于季节性的细胞正常生长。