Flowering-time regulation by the circadian clock:From Arabidopsis to crops

Precise timing of flowering in plants is critical for their growth and reproductive processes.One factor controlling flowering time is the cycle of light and darkness within a day,known as the photoperiod.Plants are classified into long-day,short-day,and day-neutral plants based on light requirements for floral initiation.Although the molecular mechanisms that govern this differentiation remain incompletely understood,studies have consistently shown that the circadian clock plays a central role in regulating photoperiod response across diverse plant species.However,there is a scarcity of reviews describing the regulatory network linking the circadian clock with photoperiodic flowering.This review summarizes that regulatory network,focusing on the distinct roles of clock genes in long-day and short-day plants.We also discuss the strategies of clock gene mutations contributing to geographic variation in longday and short-day crops.

Core clock component MtLUX controls shoot architecture through repression of MtTB1/MtTCP1A in Medicago truncatula

Plants are capable of regulating their shoot architecture in response to diverse internal and external environments.The circadian clock is an adaptive mechanism that integrates information from internal and ambient conditions to help plants cope with recurring environmental fluctuations.Despite the current understanding of plant circadian clock and genetic framework underlying plant shoot architecture,the intricate connection between these two adaptive mechanisms remains largely unclear.In this study,we elucidated how the core clock gene LUX ARRHYTHMO(LUX)regulates shoot architecture in the model legume plant Medicago truncatula.We show that mtlux mutant displays increased main stem height,reduced lateral shoot length,and decreased the number of lateral branches and biomass yield.Gene expression analysis revealed that Mt LUX regulated shoot architecture by repressing the expression of strigolactone receptor MtD14 and MtTB1/MtTCP1A,a TCP gene that functions centrally in modulating shoot architecture.In vivo and in vitro experiments showed that Mt LUX directly binds to a cis-element in the promoter of MtTB1/MtTCP1A,suggesting that Mt LUX regulates branching by rhythmically suppressing MtTB1/MtTCP1A.This work demonstrates the regulatory effect of the circadian clock on shoot architecture,offering a new understanding underlying the genetic basis towards the flexibility of plant shoot architecture.

云南多民族寺院大鼓和象脚鼓乐队、乐种的发展与现况研究

在中国云南西南部傣族、孟高棉语诸民族及相邻国家、民族地区的佛教与民俗节庆活动中,采用最多、流行最广的乐器和乐队组合是鼓(寺院大鼓或象脚鼓)、铓锣、钹三者组成的打击乐队,其表演的器乐和舞乐构成了最富于当地民族风格特色的传统乐种。随着近几十年民族音乐学研究思维的发展、引入和拓展深化,有关象脚鼓乐种的个案及比较研究及对国外东南亚国家相关研究资讯的介绍始逐渐增多,并且以国内外存活状况的分别研究和跨界族群音乐比较研究等不同方式展现出来。本文将结合对相关研究历史过程及概况的综述,对该类乐队、乐种的发展现状进行描写和讨论。

Circadian rhythms driving a fast-paced root clock implicate species-specific regulation in Medicago truncatula

Plants have a hierarchical circadian structure comprising multiple tissue-specific oscillators that operate at different speeds and regulate the expression of distinct sets of genes in different organs.However,the identity of the genes differentially regulated by the circadian clock in different organs,such as roots,and how their oscillations create functional specialization remain unclear.Here,we profiled the diurnal and circadian landscapes of the shoots and roots of Medicago truncatula and identified the conserved regulatory sequences contributing to transcriptome oscillations in each organ.We found that the light-dark cycles strongly affect the global transcriptome oscillation in roots,and many clock genes oscillate only in shoots.Moreover,many key genes involved in nitrogen fixation are regulated by circadian rhythms.Surprisingly,the root clock runs faster than the shoot clock,which is contrary to the hierarchical circadian structure showing a slow-paced root clock in both detached and intact Arabidopsis thaliana(L.)Heynh.roots.Our result provides important clues about the species-specific circadian regulatory mechanism,which is often overlooked,and possibly coordinates the timing between shoots and roots independent of the current prevailing model.