In order to flower in the appropriate season,plants monitor light and temperature changes and alter downstream pathways that regulate florigen genes such as Arabidopsis(Arabidopsis thaliana)FLOWERING LOCUS T(FT).In Ar...In order to flower in the appropriate season,plants monitor light and temperature changes and alter downstream pathways that regulate florigen genes such as Arabidopsis(Arabidopsis thaliana)FLOWERING LOCUS T(FT).In Arabidopsis,FT messenger RNA levels peak in the morning and evening under natural long-day conditions(LDs).However,the regulatory mechanisms governing morning FT induction remain poorly understood.The morning FT peak is absent in typical laboratory LDs characterized by high red:far-red light(R:FR)ratios and constant temperatures.Here,we demonstrate that ZEITLUPE(ZTL)interacts with the FT repressors TARGET OF EATs(TOEs),thereby repressing morning FT expression in natural environments.Under LDs with simulated sunlight(R:FR=1.0)and daily temperature cycles,which are natural LD-mimicking environmental conditions,FT transcript levels in the ztl mutant were high specifically in the morning,a pattern that was mirrored in the toe1 toe2 double mutant.Low night-to-morning temperatures increased the inhibitory effect of ZTL on morning FT expression by increasing ZTL protein levels early in the morning.Far-red light counteracted ZTL activity by decreasing its abundance(possibly via phytochrome A(phyA))while increasing GIGANTEA(GI)levels and negatively affecting the formation of the ZTL-GI complex in the morning.Therefore,the phyA-mediated high-irradiance response and GI play pivotal roles in morning FT induction.Our findings suggest that the delicate balance between low temperature-mediated ZTL activity and the far-red light-mediated functions of phyA and GI offers plants flexibility in fine-tuning their flowering time by controlling FT expression in the morning.展开更多
Plants constantly survey the surrounding environment using several sets of photoreceptors. They can sense changes in the quantity （= intensity） and quality （=wavelength） of light and use this information to adjust...Plants constantly survey the surrounding environment using several sets of photoreceptors. They can sense changes in the quantity （= intensity） and quality （=wavelength） of light and use this information to adjust their physiological responses, growth, and developmental patterns. In addition to the classical photoreceptors, such as phytochromes, crypto- chromes, and phototropins, ZEITLUPE （ZTL）, FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 （FKF1）, and LOV KELCH PROTEIN 2 （LKP2） proteins have been recently identified as blue-light photoreceptors that are important for regulation of the circadian clock and photoperiodic flowering. The ZTL/FKF1/LKP2 protein family possesses a unique combination of domains： a blue-light-absorb- ing LOV （Light, Oxygen, or Voltage） domain along with domains involved in protein degradation. Here, we summarize recent advances in our understanding of the function of the Arabidopsis ZTL/FKF1/LKP2 proteins. We summarize the distinct pho- tochemical properties of their LOV domains and discuss the molecular mechanisms by which the ZTL/FKF1/LKP2 proteins reg- ulate the circadian clock and photoperiodic flowering by controlling blue-light-dependent protein degradation.展开更多
The timing of flowering affects the success of sexual reproduction.This developmental event also determines crop yield,biomass,and longevity.Therefore,this mechanism has been targeted for improvement along with crop d...The timing of flowering affects the success of sexual reproduction.This developmental event also determines crop yield,biomass,and longevity.Therefore,this mechanism has been targeted for improvement along with crop domestication.The underlying mechanisms of flowering are highly conserved in angiosperms.Central to these mechanisms is how environmental and endogenous conditions control transcriptional regulation of the FLOWERING LOCUS T(FT)gene,which initiates floral development under long-day conditions in Arabidopsis.Since the identification of FT as florigen,efforts have been made to understand the regulatory mechanisms of FT expression.Although many transcriptional regulators have been shown to directly influence FT,the question of how they coordinately control the spatiotemporal expression patterns of FT still requires further investigation.Among FT regulators,CONSTANS(CO)is the primary one whose protein stability is tightly controlled by phosphorylation and ubiquitination/proteasome-mediated mechanisms.In addition,various CO interaction partners,some of them previously identified as FT transcriptional regulators,positively or negatively modulate CO protein activity.The FT promoter possesses several transcriptional regulatory"blocks,"highly conserved regions among Brassicaceae plants.Different transcription factors bind to specific blocks and affect FT expression,often causing topological changes in FT chromatin structure,such as the formation of DNA loops.We discuss the current understanding of the regulation of FT expression mainly in Arabidopsis and propose future directions related to this topic.展开更多
基金supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI grant(No.19K16170 and No.23K05817 to A.K.)National Institutes of Health(NIH)(No.R01GM079712 to T.I.)the National Research Foundation(NRF)of Korea grant funded by the Korean Government(MSIT)(No.NRF-2020R1A2C1014655 andNo.NRF-2021R1A4A1032888 to Y.H.S.).
文摘In order to flower in the appropriate season,plants monitor light and temperature changes and alter downstream pathways that regulate florigen genes such as Arabidopsis(Arabidopsis thaliana)FLOWERING LOCUS T(FT).In Arabidopsis,FT messenger RNA levels peak in the morning and evening under natural long-day conditions(LDs).However,the regulatory mechanisms governing morning FT induction remain poorly understood.The morning FT peak is absent in typical laboratory LDs characterized by high red:far-red light(R:FR)ratios and constant temperatures.Here,we demonstrate that ZEITLUPE(ZTL)interacts with the FT repressors TARGET OF EATs(TOEs),thereby repressing morning FT expression in natural environments.Under LDs with simulated sunlight(R:FR=1.0)and daily temperature cycles,which are natural LD-mimicking environmental conditions,FT transcript levels in the ztl mutant were high specifically in the morning,a pattern that was mirrored in the toe1 toe2 double mutant.Low night-to-morning temperatures increased the inhibitory effect of ZTL on morning FT expression by increasing ZTL protein levels early in the morning.Far-red light counteracted ZTL activity by decreasing its abundance(possibly via phytochrome A(phyA))while increasing GIGANTEA(GI)levels and negatively affecting the formation of the ZTL-GI complex in the morning.Therefore,the phyA-mediated high-irradiance response and GI play pivotal roles in morning FT induction.Our findings suggest that the delicate balance between low temperature-mediated ZTL activity and the far-red light-mediated functions of phyA and GI offers plants flexibility in fine-tuning their flowering time by controlling FT expression in the morning.
文摘Plants constantly survey the surrounding environment using several sets of photoreceptors. They can sense changes in the quantity （= intensity） and quality （=wavelength） of light and use this information to adjust their physiological responses, growth, and developmental patterns. In addition to the classical photoreceptors, such as phytochromes, crypto- chromes, and phototropins, ZEITLUPE （ZTL）, FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 （FKF1）, and LOV KELCH PROTEIN 2 （LKP2） proteins have been recently identified as blue-light photoreceptors that are important for regulation of the circadian clock and photoperiodic flowering. The ZTL/FKF1/LKP2 protein family possesses a unique combination of domains： a blue-light-absorb- ing LOV （Light, Oxygen, or Voltage） domain along with domains involved in protein degradation. Here, we summarize recent advances in our understanding of the function of the Arabidopsis ZTL/FKF1/LKP2 proteins. We summarize the distinct pho- tochemical properties of their LOV domains and discuss the molecular mechanisms by which the ZTL/FKF1/LKP2 proteins reg- ulate the circadian clock and photoperiodic flowering by controlling blue-light-dependent protein degradation.
基金supported by grants from the National Institutes of Health(R01GM079712)MEXT KAKENHI grants(20H05910 and 22H04978).
文摘The timing of flowering affects the success of sexual reproduction.This developmental event also determines crop yield,biomass,and longevity.Therefore,this mechanism has been targeted for improvement along with crop domestication.The underlying mechanisms of flowering are highly conserved in angiosperms.Central to these mechanisms is how environmental and endogenous conditions control transcriptional regulation of the FLOWERING LOCUS T(FT)gene,which initiates floral development under long-day conditions in Arabidopsis.Since the identification of FT as florigen,efforts have been made to understand the regulatory mechanisms of FT expression.Although many transcriptional regulators have been shown to directly influence FT,the question of how they coordinately control the spatiotemporal expression patterns of FT still requires further investigation.Among FT regulators,CONSTANS(CO)is the primary one whose protein stability is tightly controlled by phosphorylation and ubiquitination/proteasome-mediated mechanisms.In addition,various CO interaction partners,some of them previously identified as FT transcriptional regulators,positively or negatively modulate CO protein activity.The FT promoter possesses several transcriptional regulatory"blocks,"highly conserved regions among Brassicaceae plants.Different transcription factors bind to specific blocks and affect FT expression,often causing topological changes in FT chromatin structure,such as the formation of DNA loops.We discuss the current understanding of the regulation of FT expression mainly in Arabidopsis and propose future directions related to this topic.
