References

1. 2. Structuralfeatureof MBF1 Fromprotiststohigherorganisms, MBF1proteinsarehighlyconservedinsequencestructure, andtheirmolecularstructuresgenerallyconsistsoftwodomains: ahighlyconserved HTHdomainbetweenspeciesatthe C-terminus, andaclearlydifferentiateddomainbetweenarchaeaandeukaryotesatthe N-terminus[. The N-terminusisaconservedzinc-ribbondomaininarchaea, whereasthe N-terminusisalessconservedandvariabledomainineukaryotes, thatcanbinddifferenttranscriptionfactorsbychangingtheconformationof MBF
2. 1. The C-terminus80aminoacidresiduesof MBF1canformawell-structured-helicesanda C-terminustail, whichisnecessaryfor MBF1tobridge TBP. International Journalof Multidisciplinary Researchand Growth Evaluationwww. allmultidisciplinaryjournal. com1542|Page Indifferentbiologicalorganisms, theaminoacidsequences-helicalhydrophobicresiduesof MBF1homologousproteinsarehighlyconserved, andtheproteinfoldingformsarealsobasicallyconsistent; theaminoacidsequenceofthe C-terminaltailisalsohighlysimilar, whichismainlyresponsibleformaintainingthestabilityofproteintertiarystructure, butthistailstructuredoesnotexistinsomeplant MBF1s[. Theconservationofthe C-terminusmayindicatethatitisessentialforthestructuralorfunctionalintegrityofthe MBF1proteins.
3. 3. Themodeofactionof MBF1MBF1mainlyfunctionsasatranscriptionalcoactivatorintheprocessofgenetranscriptionregulation, anditsfunctionistobridgetheuniversaltranscriptionfactor TBPandgenespecifictranscriptionfactors, recruitgenespecifictranscriptionfactorstothepromoterofthetargetgene, andactivatethetranscriptionofthetargetgenetoregulatethevariouslifeactivitiesoftheorganism. TBPisatranscriptionfactorthatcanrecognizeandbindtothe TATAboxonthepromoterofgene, andispresentinalleukaryotes. However, thetypesof MBF1-assistedactivationoftranscriptionfactorsarenotcompletelyconsistentindifferentspecies. Currently, twomaintypeshavebeenidentified: thenuclearreceptortype(FTZ-e(GCN4, CREB, ATF1, TDF, Ha HB4, AP-1\[. Thediversityofbridgingtranscriptionfactortypesindicatesthat MBF1isinvolvedintheregulationofmultipledevelopmentalandmetabolicprocessesindifferentbiologicalorganisms.
4. 4. Coevolutionof MBF1and TBPThephysicalinteractionbetween MBF1and TBPishighlyconservedfromprotiststohigherorganisms, andthekeyaminoacidsinvolvedintheinteractionbetween MBF1and TBPshowsignificantcoevolutionaryrelationshipsduringevolution. Thestudyoftheaminoacidresiduesattheinteractionsitesof MBF1and TBPshowedthatthekeyaminoacidsinthe MBF1and TBPofyeastare Datposition112and Qatposition68, whileinplanttheywere Eand Q, respectively[. MBF1and TBP, asthecorecomponentsoftheeukaryotictranscriptionalregulatorynetwork, havebeenselectedtointeractwitheachotherforaminoacidcompensatorychangesinevolution, andtheircoevolutionaryrelationshipreflectstheadaptiveevolutionoffunctionandstructure. Theinteractionbetween MBF1and TBPishighlyconservedacrossspecies, andtheirstructuressynergisticallyoptimizethestabilityofthetranscriptioncomplex. Thisconservedinteractionmaybeduetotheircoreroleinsupportingbasictranscriptionalmechanisms.
5. 5. Expressionpatternof MBF1inplanttissues MBF1geneswereexpressedubiquitouslyinalldevelopmentalstagesofplantandinalltestedorgans, includingroot, stem, leaf, flower, fruitandseed. MBF1geneshaveaspatiotemporalexpressionpatternduringplantgrowthanddevelopment, andtheirexpressionlevelvariesaccordingtotheplantdevelopmentstage, speciesandenvironmentalconditions. In Arabidopsis(Col\, theexpressionof At MBF1a, At MBF1b, and At MBF1cwerefoundinalltestedtissues, includingleaves, roots, stems, flowers, andsiliques. Althoughthethree MBF1sin Arabidopsisareuniversallyexpressedinalltissues, therearesignificantdifferencesintheexpressionlevelsofeach MBF1indifferenttissues, with At MBF1abeingmorehighlyexpressedinflowers, At MBF1bbeingstronglyexpressedinleaves, stems, flowers, andangiosperms, and At MBF1cbeingmoreabundantinleavesandroots[. Inhotpepper(P70\, Ca MBF1isgenerallyexpressedinalltestedtissues, withthehigherexpressionlevelinseedsandflowers, themoderateexpressionlevelinfruit, stem, andleaf, andthelowerexpressionlevelinroots[. Attheheadingstageofhexaploidwheat(CB037\, Ta MBF1c-7 Bwaswidelyexpressedinalltestedtissues, withthehigherexpressionlevelincob, themoderateexpressionlevelinrootsandstamens, andthelowerexpressionlevelinstems, leaves, awns, glumes, palea, palea, andpistils[. Theuniversalexpressionof MBF1inallplanttissuessuggeststhat MBF1playsanimportantroleinplantgrowthanddevelopment, whereasthedifferentialexpressionofeach MBF1indifferentplantagesanddifferentplanttissuessuggeststhatdifferent MBF1smayplaydifferentrolesatdifferentdevelopmentalstages.
6. 6. Roleof MBF1inplantgrowthanddevelopment MBF1playsanimportantroleinplantseedgermination, stemandleafelongation, flowering, seedsettingrateandotherdevelopmentalprocesses. Therearefewreportsontheroleof MBF1inplantgrowthanddevelopment, andcurrentlyitmainlyfocusesonthemodelplant Arabidopsis. In Arabidopsis, At MBF1ccontrolsleafcellcycleandleafexpansion, andisinvolvedinthepositiveregulationofseedgerminationandplantgrowth. In Arabidopsis, theseedgerminationrateof Atmbf1cmutantsissignificantlyreducedcomparedtothewildtype[. Overexpressionof At MBF1cin Arabidopsisleadstoincreasedplantmorphology, earlyflowering, andincreasedseednumber[. Overexpressionof At MBF1bor At MBF1cfusedwiththestrongtranscriptionalrepressiondomain SRDXin Arabidopsisresultedinsignificantplantdwarfism, delayedstemelongation, shortenedpetioleandleaflength, reducedhornlengthandseednumber[. Nonehasspecificallyaddressedtheirroleinthisprocess, althoughsomephenotypeshavebeendescribedforafewoverexpressionandmutantlines.
7. 7. Roleof MBF1inplantabioticstressresponses7.
8. 1. Roleof MBF1inplantheatstressresponse Theroleof MBF1inplanthightemperaturestressresponsehasattractedmuchattentionandhasbeenstudiedinavarietyofplants. Theupregulatedexpressionof MBF1inducedbyhightemperaturestresswasobservedin Arabidopsis, wheat, tomato, andpepper. In Arabidopsis, At MBF1cisakeyregulatoryfactorinplanthightemperaturestressresponse. At MBF1ccanenhanceplanttolerancetohightemperaturestressbyregulatingtheexpressionofdownstreamtargetgenessuchas HSFB2A, HSFB2B, and DREB2A[. At MBF1ccanalsoregulatetrehalosemetabolismbyinteractingwith TPS5, andparticipateintheregulationofplantbasalheattolerance[. Intomato, Sl MBF1cpositivelyregulatesthepollenheattolerance[. Inwheat, asacomponentofheatstressgranule(HSG\, canimproveheatresistancebyregulatingthetranslationefficiencyofspecifichightemperaturestressresponsivegenesunderhightemperaturestressconditions[.7.
9. 2. Roleof MBF1inplantcoldstressresponse Theroleof MBF1inplantresponsetolowtemperaturestressremainsunclear. In Arabidopsis, theexpressionlevelof At MBF1cwasnotaffectedbylowtemperaturestress, andthecoldtoleranceoftransgenic Arabidopsisoverexpressing International Journalof Multidisciplinary Researchand Growth Evaluationwww. allmultidisciplinaryjournal. com1543|Page At MBF1chadnosignificantchangecomparedtothewildtype[. However, theexpressionof Ca MBF1inhotpepperwasupregulatedbylowtemperaturestress, andtransgenic Arabidopsisoverexpressing Ca MBF1showedincreasedsensitivitytolowtemperaturestress. Furtherstudiesrevealedthat Ca MBF1negativelyregulatedtheexpressionoflow-temperaturestressresponse-relatedgenessuchas RD29A, ERD15, KINI, RD22, PDF1.2and PR2, indicatingthat Ca MBF1mayfunctionasanegativeregulatoryfactorinresponsetolowtemperaturestressinhotpepper[. Overexpressionofthe Bp MBF1fromthe Antarcticcanimprovethecoldresistancein Arabidopsisandpoplar. Furtherresearchhasfoundthat Bp MBF1mayenhanceplantcoldresistancebyregulatingintracellularhormonelevelsandcellmembranestability[.7.
10. 3. Roleof MBF1inplantdroughtstressresponse MBF1isinducedtoupregulateexpressionbydroughtstressin Arabidopsis, wheat, riceandgrape. Transcriptomeprofilingandinhibitorstudiessuggestthat At MBF1cexpressionenhancesthetoleranceoftransgenicplantstodroughtstressbypartiallyactivating, orperturbing, theethylene-responsesignaltransductionpathway[. Vv MBF1islikelyinvolvedindrought-responsivenessingrape, andconfersincreaseddroughttoleranceintransgenicplants, possiblythroughan ABA-dependentsignaltransductionpathway[. Pw MBF1cexpressionissignificantlyupregulatedbydroughtstressin Picea Wilsonii, andheterologousoverexpressionof Pw MBF1csignificantlyimprovesthedroughttolerancein Arabidopsisandpotato[.7.
11. 4. Roleof MBF1inplantsaltstressresponse MBF1playsanimportantroleinplantsaltstressresponse, and MBF1geneshavebeenidentifiedinseveralplantstorespondtosaltstress. At MBF1aisupregulatedundersaltstressin Arabidopsis, andoverexpressionof At MBF1acansignificantlyimprovethesalttolerancein Arabidopsisseedlings, andinducetheexpressionofstressresponsivegenessuchas RD26A, RD22, and KIN2[. Dg MBF1isupregulatedbysaltstressinchrysanthemum, andoverexpressionof Dg MBF1significantlycanenhancethesalttoleranceinchrysanthemum[. Pa MBF1cissignificantlyupregulatedbysaltstressin Antarctic, andoverexpressionof Pa MBF1ccanimprovethesalttolerancein Arabidopsisbyenhancing ROSdetoxification, maintaining ATPmechanisms[. Contrarytowhathasbeenobservedinotherplants, Ca MBF1expressionisdrasticallydownregulatedinresponsetosaltstressinhotpepper, andoverexpressionof Ca MBF1canenhancethesensitivitytosaltstressin Arabidopsis[.7.
12. 5. Roleof MBF1inplantotherabioticstressresponses MBF1isalsoinvolvedinotherabioticstressessuchasoxidativestress, osmoticstressandwaterloggingstress. H2O2treatmentsleadtoanincreasein MBF1transcriptin Pyropiayezoensis, Arabidospsis, andwheat[. In Arabidopsis, At MBF1cparticipatesintheosmoticstressresponseandconferstolerancetothisstressduringgermination[. Inchrysanthemums, Cm MBF1cwassignificantlyinducedbywaterloggingstress, andoverexpressionof Cm MBF1cin'Qinglu'enhanceditswaterloggingtolerancebypromotingitsreactiveoxygenspecies(ROS\scavengingabilityandmaintaininglow ROSlevels. Furtherresearchfoundthat Cm MBF1cimproveschrysanthemumwaterloggingtolerancebyregulatingits ROSsignalingpathwayandinteractingwith Cm HRE2[. Inconclusion, MBF1transcriptionalcoactivatorfamilymemberscanhelpplantsresistabioticstressbymaintaininggrowthphysiologicalindicators, regulatingstressresponsegenesexpressionandparticipatinginmultiplesignalingpathwaysunderabioticstressconditionssuchashightemperature, lowtemperature, drought, highsalinity, oxidationandwaterlogging.
13. 8. Discussionand Prospects Currentresearchhasshownthat MBF1transcriptionalcoactivatorsplayimportantrolesinplantgrowthanddevelopment, aswellasinresponsetoabioticstress, buttherearestillmanyaspectsthatdeservetobeinvestigatedindepth. Thespecificroleof MBF1inplantgrowthanddevelopmenthasnotbeenfullystudied, andmorescientificresearchisneededinthefuturetogainadeeperunderstandingofthisarea. MBF1, asakeyregulatorynodeinplantstressresponse, notonlydeepenstheunderstandingofplantadaptationmechanisms, butalsoprovidesimportantgeneticresourcesforsustainableagriculturaldevelopment. Withthedevelopmentofmolecularbiologytechnology, thefunctionalanalysisandapplicationpotentialof MBF1willusherinbroaderprospects. Studiesof MBF1homologousgenesindifferentspecieshaveshownthatplant MBF1sareinvolvedinvariousabioticstressresponses, butthespecifictargetgenesandmolecularregulatorymechanismsof MBF1inavarietyofstressresponsesneedtobefurtherstudied. Furthermore, innature, coercionismorelikelytooccursimultaneouslyratherthanasisolatedindividualevents. Therefore, themoleculardiversityof MBF1makesitanidealcandidateforintegratingmultiplestressconditions. Howdoes MBF1integratestressstimulithatoccursimultaneously?Howdoes MBF1coordinateplantstressresponsewithgrowthanddevelopmentpathways?Allofthesearethequestionsweneedtoansweraswedelveintothebiologicalfunctionsoftheplant MBF1ttranscriptionalcoactivatorfamily.
14. 9. Funding: Thisworkwassupportedbygrantsfromthe College Student Innovationand Entrepreneurship Training Program(202311336014\, the Opening Projectof Hubei Engineering Research Centerfor Specialty Flowers Biological Breeding(2022ZD008\, andthe Developmentof Selenium Mediated Disease Resistanceand Fruit Quality Enhancement Technologyin Citrus(HZ250018\.
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