查看更多>>摘要：The development of flowers in soybean(Glycine max)is essential for determining the yield potential of the plant.Gene silencing pathways are involved in modulating flower development,but their full elucidation is still incomplete.Here,we conducted a forward genetic screen and identified an abnormal flower mutant,deformed floral bud1-1(Gmdfb1-1),in soybean.We mapped and identified the causal gene,which encodes a member of the armadillo(ARM)-repeat superfamily.Using small RNA se-quencing(sRNA-seq),we found an abnormal ac-cumulation of small interfering RNAs(siRNAs)and microRNA(miRNAs)in the Gmdfb1 mutants.We further demonstrated that GmDFB1 interacts with the RNA exosome cofactor SUPER KILLER7(GmSKI7).Additionally,GmDFB1 interacts with the PIWI domain of ARGONAUTE1(GmAGO1)to inhibit the cleavage efficiency on the target genes of sRNAs.The enhanced gene silencing mediated by siRNA and miRNA in the Gmdfb1 mutants leads to the downregulation of their target genes associated with flower development.This study revealed the crucial role of GmDFB1 in regulating floral organ identity in soybean probably by participating in two distinct gene silencing pathways.
查看更多>>摘要：Callose,a β-1,3-glucan plant cell wall polymer,reg-ulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose homeostasis is limited.We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene was α1-COP,a member of the coat protein Ⅰ(COPⅠ)coatomer complex.We report that loss of function of α1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degrada-tion enzyme PdBG2.This process is linked to the functions of ERH1,an inositol phosphoryl ceramide synthase,and glucosylceramide synthase through physical interactions with the α1-COP protein.Ad-ditionally,the loss of function of α1-COP alters the subcellular localization of ERH1 and GCS proteins,resulting in a reduction of GlcCers and GlcHCers molecules,which are key sphingolipid(SL)species for lipid raft formation.Our findings suggest that α1-COP protein,together with SL modifiers controlling lipid raft compositions,regulates the subcellular localization of GPI-anchored PDBG2 proteins,and hence the callose tumover at PD and symplasmic movement of biomolecules.Our findings provide the first key clue to link the COPⅠ-mediated intracellular trafficking pathway to the callose-mediated inter-cellular signaling pathway through PD.
查看更多>>摘要：The biosynthesis of cellulose,lignin,and hemi-celluloses in plant secondary cell walls(SCWs)is regulated by a hierarchical transcriptional regulatory network.This network features or-thologous transcription factors shared between poplar and Arabidopsis,highlighting a founda-tional similarity in their genetic regulation.However,knowledge on the discrepant behavior of the transcriptional-level molecular regulatory mechanisms between poplar and Arabidopsis remains limited.In this study,we investigated the function of PagMYB128 during wood for-mation and found it had broader impacts on SCW formation compared to its Arabidopsis ortholog,AtMYB103.Transgenic poplar trees overexpressing PagMYB128 exhibited sig-nificantly enhanced xylem development,with fiber cells and vessels displaying thicker walls,and an increase in the levels of cellulose,lignin,and hemicelluloses in the wood.In contrast,plants with dominant repression of PagMYB128 demonstrated the opposite phenotypes.RNA sequencing and reverse transcription-quantitative polymerase chain reaction showed that PagMYB1 28 could ac-tivate SCW biosynthetic gene expression,and chromatin immunoprecipitation along with yeast one-hybrid,and effector-reporter assays showed this regulation was direct.Further analysis revealed that PagSND1(SECONDARY WALL-ASSOCIATED NAC-DOMAIN PROTEIN1)directly regulates PagMYB128 but not cell wall metabolic genes,highlighting the pivotal role of PagMYB1 28 in the SND1-driven regulatory network for wood devel-opment,thereby creating a feedforward loop in SCW biosynthesis.
查看更多>>摘要：AUXIN RESPONSE FACTOR 7(ARF7)-mediated auxin signaling plays a key role in lateral root(LR)development by regulating downstream LATERAL ORGAN BOUNDARIES DOMAIN(LBD)transcription factor genes,including LBD16,LBD18,and LBD29.LBD proteins are believed to regulate the transcription of downstream genes as homodimers or heterodimers.However,whether LBD29 forms dimers with other proteins to regulate LR development remains unknown.Here,we determined that the Arabidopsis thaliana(L.)Heynh.MYB transcription factors MYB2 and MYB108 interact with LBD29 and regulate auxin-induced LR development.Both MYB2 and MYB108 were induced by auxin in an ARF7-dependent manner.Disruption of MYB2 by fusion with an SRDX domain severely affected auxin-induced LR formation and the ability of LBD29 to induce LR development.By contrast,overexpression of MYB2 or MYB108 resulted in greater LR numbers,except in the Ibd29 mutant background.These findings underscore the interdependence and importance of MYB2,MYB108,and LBD29 in regulating LR develop-ment.In addition,MYB2-LBD29 and MYB108-LBD29 complexes promoted the expression of CUTICLE DESTRUCTING FACTOR 1(CDEF1),a member of the GDSL(Gly-Asp-Ser-Leu)lipase/esterase family involved in LR development.In summary,this study identified MYB2-LBD29 and MYB108-LBD29 regulatory modules that act downstream of ARF7 and intricately control auxin-mediated LR development.
查看更多>>摘要：The ancient crop broomcom millet(Panicum miliaceum L.)is an indispensable orphan crop in semi-arid regions due to its short life cycle and excellent abiotic stress tolerance.These ad-vantages make it an important alternative crop to increase food security and achieve the goal of zero hunger,particularly in light of the uncertainty of global climate change.However,functional ge-nomic and biotechnological research in broom-com millet has been hampered due to a lack of genetic tools such as transformation and genome-editing techniques.Here,we successfully per-formed genome editing of broomcorn millet.We identified an elite variety,Hongmi,that produces embryogenic callus and has high shoot re-generation ability in in vitro culture.We established an Agrobacterium tumefaciens-mediated genetic transformation protocol and a clustered regularly interspaced short palindromic repeats(CRISPR)/Cas9-mediated genome-editing system for Hongmi.Using these techniques,we produced herbicide-resistant transgenic plants and edited phytoene desaturase(PmPDS),which is involved in chlorophyll biosynthesis.To facilitate the rapid adoption of Hongmi as a model line for broomcorn millet research,we assembled a near-complete genome sequence of Hongmi and compre-hensively annotated its genome.Together,our re-sults open the door to improving broomcom millet using biotechnology.
查看更多>>摘要：Aporphine alkaloids have diverse pharmacological activities;however,our understanding of their biosynthesis is relatively limited.Previous studies have classified aporphine alkaloids into two cat-egories based on the configuration and number of substituents of the D-ring and have proposed preliminary biosynthetic pathways for each cat-egory.In this study,we identified two specific cy-tochrome P450 enzymes(CYP80G6 and CYP80Q5)with distinct activities toward(S)-configured and(R)-configured substrates from the herbaceous perennial vine Stephania tetrandra,shedding light on the biosynthetic mechanisms and stereo-chemical features of these two aporphine alkaloid categories.Additionally,we characterized two CYP719C enzymes(CYP719C3 and CYP719C4)that catalyzed the formation of the methylenedioxy bridge,an essential pharmacophoric group,on the A-and D-rings,respectively,of aporphine al-kaloids.Leveraging the functional characterization of these crucial cytochrome P450 enzymes,we re-constructed the biosynthetic pathways for the two types of aporphine alkaloids in budding yeast(Saccharomyces cerevisiae)for the de novo pro-duction of compounds such as(R)-glaziovine,(S)-glaziovine,and magnoflorine.This study pro-vides key insight into the biosynthesis of aporphine alkaloids and lays a foundation for producing these valuable compounds through synthetic biology.
查看更多>>摘要：Phytohormones,epigenetic regulation and envi-ronmental factors regulate fruit ripening but their interplay during strawberry fruit ripening remains to be determined.In this study,bagged straw-berry fruit exhibited delayed ripening compared with fruit grown in normal light,correlating with reduced abscisic acid(ABA)accumulation.Transcription of the key ABA catabolism gene,ABA 8'-hydroxylase FaCYP707A4,was induced in bagged fruit.With light exclusion whole genome DNA methylation levels were up-regulated,cor-responding to a delayed ripening process,while DNA methylation levels in the promoter of FaCYP707A4 were suppressed,correlating with increases in transcript and decreased ABA con-tent.Experiments indicated FaCRY1,a blue light receptor repressed in bagged fruit and FaAGO4,a key protein involved in RNA-directed DNA methylation,could bind to the promoter of FaCYP707A4.The interaction between FaCRY1 and FaAGO4,and an increased enrichment of FaAGO4 directed to the FaCYP707A4 promoter in fruit grown under light suggests FaCRY1 may influence FaAGO4 to modulate the DNA methyl-ation status of the FaCYP707A4 promoter.Fur-thermore,transient overexpression of FaCRY1,or an increase in FaCRY1 transcription by blue light treatment,increases the methylation level of the FaCYP707A4 promoter,while transient RNA in-terference of FaCRY1 displayed opposite phe-notypes.These findings reveal a mechanism by which DNA methylation influences ABA catabo-lism,and participates in light-mediated straw-berry ripening.
查看更多>>摘要：The sesquiterpene lactone artemisinin is an im-portant anti-malarial component produced by the glandular secretory trichomes of sweet wormwood(Artemisia annua L.).Light was previously shown to promote artemisinin production,but the underlying regulatory mechanism remains elusive.In this study,we demonstrate that ELONGATED HYPOCOTYL 5(HY5),a central transcription factor in the light sig-naling pathway,cannot promote artemisinin biosyn-thesis on its own,as the binding of AaHY5 to the promoters of artemisinin biosynthetic genes failed to activate their transcription.Transcriptome analysis and yeast two-hybrid screening revealed the B-box transcription factor AaBBX21 as a potential interactor with AaHY5.AaBBX21 showed a trichome-specific expression pattern.Additionally,the AaBBX21-AaHY5 complex cooperatively activated transcription from the promoters of the downstream genes AaGSW1,AaMYB108,and AaORA,encoding pos-itive regulators of artemisinin biosynthesis.Moreover,AaHY5 and AaBBX21 physically interacted with the A.annua E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1(COP1).In the dark,AaCOP1 decreased the accumulation of AaHY5 and AaBBX21 and repressed the activation of genes downstream of the AaHY5-AaBBX21 complex,ex-plaining the enhanced production of artemisinin upon light exposure.Our study provides insights into the central regulatory mechanism by which light governs terpenoid biosynthesis in the plant kingdom.
查看更多>>摘要：Dwarfing is a pivotal agronomic trait affecting both yield and quality.Citrus species exhibit substantial variation in plant height,among which internode length is a core element.However,the molecular mechanism governing internode elongation remains unclear.Here,we unveiled that the transcriptional cascade con-sisting of B-BOX DOMAIN PROTEIN 22(BBX22)and ELONGATED HYPOCOTYL 5(HY5)finely tunes plant height and internode elongation in citrus.Loss-of-function mutations of BBX22 in an early-flowering citrus(Citrus hindsii"SJG")promoted internode elongation and reduced pigment accumulation,whereas ectopic ex-pression of BBX22 in SJG,sweet orange(C.sinensis),pomelo(C.maxima)or heterologous expression of BBX22 in tomato(Solanum lyco-persicum)significantly decreased internode length.Furthermore,exogenous application of gibberellin A3(GA3)rescued the shortened in-ternode and dwarf phenotype caused by BBX22 overexpression.Additional experiments re-vealed that BBX22 played a dual role in regu-lation internode elongation and pigmentation in citrus.On the one hand,it directly bound to and activated the expression of HY5,GA metabo-lism gene(GA2 OXIDASE 8,GA2ox8),car-otenoid biosynthesis gene(PHYTOENE SYN-THASE 1,PSY1)and anthocyanin regulatory gene(Ruby1,a MYB DOMAIN PROTEIN).On the other hand,it acted as a cofactor of HY5,en-hancing the ability of HY5 to regulate target genes expression.Together,our results reveal the critical role of the transcriptional cascade consisting of BBX22 and HY5 in controlling in-ternode elongation and pigment accumulation in citrus.Unraveling the crosstalk regulatory mechanism between internode elongation and fruit pigmentation provides key genes for breeding of novel types with both dwarf and health-beneficial fortification in citrus.
查看更多>>摘要：Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resist-ance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,re-sulting in a robust immune response and hyper-sensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae pv.pisi has been well studied in terms of avirulence function.In planta,AvrRps4 is processed into two parts.The C-terminal fragment of AvrRps4(AvrRps4C)induces HR in tumip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in Arabidopsis.Here,we show that AvrRps4C targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence function.Indeed,AvrRps4C suppresses the general binding and tran-scriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated resistance.AvrRps4C interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4C.Through the interaction of AvrRps4C with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and seques-ters them in the cytoplasm,thus inhibiting their function in plant immunity.Together,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.
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