Spinach (Spinacia oleracea L.) develops leaf rosettes under short-day conditions, and starts reproductive growth including bolting and flowering under long-day conditions. Japanese people prefer Oriental spinach that ...Spinach (Spinacia oleracea L.) develops leaf rosettes under short-day conditions, and starts reproductive growth including bolting and flowering under long-day conditions. Japanese people prefer Oriental spinach that bolts easily with a shorter photoperiod than European spinach. This is one of the main reasons that Oriental spinach is difficult to grow year-round. In order to understand spinach flowering mechanisms and obtain knowledge for spinach breeding, we isolated one CONSTANS-like (COL) and two FLOWERING LOCUS T (FT) homologs, which are key components of photoperiodic regulation of flowering time, from a Japanese cultivar. The expression of SoCOL1 showed diurnal rhythm with the highest expression at the end of the dark cycle. This diurnal rhythm is similar to the expression of BvCOL1 from sugar beet (Beta vulgaris), whose flower-promoting effect was observed when overexpressed in Arabidopsis. Phylogenetic analysis showed that SoCOL1 is the closest homolog of BvCOL1, suggesting that SoCOL1 is an ortholog of BvCOL1. SoFT1 and SoFT2 are closely related to BvFT1 and BvFT2, respectively. The expression of SoFT1 and SoFT2 were induced in advance of flower bud formation after changing the photoperiod, but the expression level of SoFT1 was much lower than SoFT2. Currently, we are speculating that SoFT2 is a flower-promoting factor of spinach, and that SoFT1 has a role in light signaling because the expression of SoFT1 showed a diurnal rhythm.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
The transcription factor CONSTANS(CO)integrates day-length information to induce the expression of florigen FLOWERING LOCUS T(FT)in Arabidopsis.We recently reported that the C-terminal CCT domain of CO forms a complex...The transcription factor CONSTANS(CO)integrates day-length information to induce the expression of florigen FLOWERING LOCUS T(FT)in Arabidopsis.We recently reported that the C-terminal CCT domain of CO forms a complex with NUCLEAR FACTOR-YB/YC to recognize multiple cis-elements in the FT promoter,and the N-terminal tandem B-box domains form a homomultimeric assembly.However,the mechanism and biological function of CO multimerization remained unclear.Here,we report that CO takes on a head-to-tail oligomeric configuration via its B-boxes to mediate FT activation in long days.The crystal structure of B-boxesCOreveals a closely connected tandem B-box fold forming a continuous head-to-tail assembly through unique CDHH zinc fingers.Mutating the key residues involved in CO oligomerization resulted in a non-functional CO,as evidenced by the inability to rescue co mutants.By contrast,a transgene encoding a human p53-derived tetrameric peptide in place of the B-boxesCOrescued co mutant,emphasizing the essential role of BboxesCO-mediated oligomerization.Furthermore,we found that the four TGTG-bearing cis-elements in FT proximal promoter are required for FT activation in long days.Our results suggest that CO forms a multimer to bind to the four TGTG motifs in the FT promoter to mediate FT activation.展开更多
In Arabidopsis,photoperiodic flowering is controlled by the regulatory hub gene CONSTANS(CO),whereas floral organ senescence is regulated by the jasmonates(JAs).Because these processes are chronologically ordered,it r...In Arabidopsis,photoperiodic flowering is controlled by the regulatory hub gene CONSTANS(CO),whereas floral organ senescence is regulated by the jasmonates(JAs).Because these processes are chronologically ordered,it remains unknown whether there are common regulators of both processes.In this study,we discovered that CO protein accumulates in Arabidopsis flowers after floral induction,and it displays a diurnal pattern in floral organs different from that in the leaves.We observed that altered CO expression could affect flower senescence and abscission by interfering with JA response,as shown by petal-specific transcriptomic analysis as well as CO overexpression in JA synthesis and signaling mutants.We found that CO has a ZIM(ZINC-FINGER INFLORESCENCE MERISTEM)like domain that mediates its interaction with the JA response repressor JAZ3(jasmonate ZIM-domain 3).Their interaction inhibits the repressor activity of JAZ3,resulting in activation of downstream transcription factors involved in promoting flower senescence.Furthermore,we showed that CO,JAZ3,and the E3 ubiquitin ligase COI1(Coronatine Insensitive 1)could form a protein complex in planta,which promotes the degradation of both CO and JAZ3 in the presence of JAs.Taken together,our results indicate that CO,a key regulator of photoperiodic flowering,is also involved in promoting flower senescence and abscission by augmenting JA signaling and response.We propose that coordinated recruitment of photoperiodic and JA signaling pathways could be an efficient way for plants to chronologically order floral processes and ensure the success of offspring production.展开更多
文摘Spinach (Spinacia oleracea L.) develops leaf rosettes under short-day conditions, and starts reproductive growth including bolting and flowering under long-day conditions. Japanese people prefer Oriental spinach that bolts easily with a shorter photoperiod than European spinach. This is one of the main reasons that Oriental spinach is difficult to grow year-round. In order to understand spinach flowering mechanisms and obtain knowledge for spinach breeding, we isolated one CONSTANS-like (COL) and two FLOWERING LOCUS T (FT) homologs, which are key components of photoperiodic regulation of flowering time, from a Japanese cultivar. The expression of SoCOL1 showed diurnal rhythm with the highest expression at the end of the dark cycle. This diurnal rhythm is similar to the expression of BvCOL1 from sugar beet (Beta vulgaris), whose flower-promoting effect was observed when overexpressed in Arabidopsis. Phylogenetic analysis showed that SoCOL1 is the closest homolog of BvCOL1, suggesting that SoCOL1 is an ortholog of BvCOL1. SoFT1 and SoFT2 are closely related to BvFT1 and BvFT2, respectively. The expression of SoFT1 and SoFT2 were induced in advance of flower bud formation after changing the photoperiod, but the expression level of SoFT1 was much lower than SoFT2. Currently, we are speculating that SoFT2 is a flower-promoting factor of spinach, and that SoFT1 has a role in light signaling because the expression of SoFT1 showed a diurnal rhythm.
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.
基金supported by the Shenzhen Science and Technology Program(JCYJ20200109110403829 and KQTD20190929173906742 to Jiamu Du)the National Natural Science Foundation of China(31721001 to Yuehui He)+1 种基金the National Key Research and Development Program of China(2017YFA0503803 to Yuehui He)the Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006 to Jiamu Du)。
文摘The transcription factor CONSTANS(CO)integrates day-length information to induce the expression of florigen FLOWERING LOCUS T(FT)in Arabidopsis.We recently reported that the C-terminal CCT domain of CO forms a complex with NUCLEAR FACTOR-YB/YC to recognize multiple cis-elements in the FT promoter,and the N-terminal tandem B-box domains form a homomultimeric assembly.However,the mechanism and biological function of CO multimerization remained unclear.Here,we report that CO takes on a head-to-tail oligomeric configuration via its B-boxes to mediate FT activation in long days.The crystal structure of B-boxesCOreveals a closely connected tandem B-box fold forming a continuous head-to-tail assembly through unique CDHH zinc fingers.Mutating the key residues involved in CO oligomerization resulted in a non-functional CO,as evidenced by the inability to rescue co mutants.By contrast,a transgene encoding a human p53-derived tetrameric peptide in place of the B-boxesCOrescued co mutant,emphasizing the essential role of BboxesCO-mediated oligomerization.Furthermore,we found that the four TGTG-bearing cis-elements in FT proximal promoter are required for FT activation in long days.Our results suggest that CO forms a multimer to bind to the four TGTG motifs in the FT promoter to mediate FT activation.
基金Authors would like to acknowledge the help or Drs.M,Calonje.And D.Pozo,and prof.M.A,Blazquez for critical reading of the manuscriptWork by G.S.-B.was supported by a European.Union.contract LONGFLOW(MSCAIF-2018-838317)+1 种基金CSICLONGFLOW_(CON-V_EXT_014)Wealso acknowledge financial support of from the Spanish Ministry for Science and Innovations(MICINN/FEDER)grants BIO2017-84066-R(to.F.V.),PPID2020-117018RB-100(to F.V.),and PID2019-107012RB-100(to R.S.and A.C.).
文摘In Arabidopsis,photoperiodic flowering is controlled by the regulatory hub gene CONSTANS(CO),whereas floral organ senescence is regulated by the jasmonates(JAs).Because these processes are chronologically ordered,it remains unknown whether there are common regulators of both processes.In this study,we discovered that CO protein accumulates in Arabidopsis flowers after floral induction,and it displays a diurnal pattern in floral organs different from that in the leaves.We observed that altered CO expression could affect flower senescence and abscission by interfering with JA response,as shown by petal-specific transcriptomic analysis as well as CO overexpression in JA synthesis and signaling mutants.We found that CO has a ZIM(ZINC-FINGER INFLORESCENCE MERISTEM)like domain that mediates its interaction with the JA response repressor JAZ3(jasmonate ZIM-domain 3).Their interaction inhibits the repressor activity of JAZ3,resulting in activation of downstream transcription factors involved in promoting flower senescence.Furthermore,we showed that CO,JAZ3,and the E3 ubiquitin ligase COI1(Coronatine Insensitive 1)could form a protein complex in planta,which promotes the degradation of both CO and JAZ3 in the presence of JAs.Taken together,our results indicate that CO,a key regulator of photoperiodic flowering,is also involved in promoting flower senescence and abscission by augmenting JA signaling and response.We propose that coordinated recruitment of photoperiodic and JA signaling pathways could be an efficient way for plants to chronologically order floral processes and ensure the success of offspring production.
