MechanismofphotosyntheticresponseinMicrocystisaeruginosaPCC7806tolowinorganicphosphorusContents1.Introduction3.Resultanddiscussion2.Materialsandmethods4.ConclusionSRP

playsacrucialroleindeterminingpotentialproductivityofbloom-forming

cyanobacteria.NutrienthasaconsiderableeffectonMicrocystisphotosynthetic

characteristics.Phospholipidsareindispensablecomponentsofbiomembranes.P-deficiencyrestrictsphotophosphorylation,andleadstoa

higherexcitedstateofthylakoidmembrane,lowerelectrontransportrateandrelatively

inefficientoperationofphotosynthesis.IntroductionMechanismof

photosyntheticresponseinM.a

underlowinorganicphosphatefromthreeaspects:(1)

thegrowthratesandrapidlightcurves(RLC);(2)photosyntheticenergytransferwhichrelatedtothethylakoidmembranefluidity;(3)thephotosyntheticcarbonassimilationM.aeruginosaPCC7806Materialsandmethodsculturefourdifferentconcentrationscentrifugedphosphorusstarvedfor72h(0.005mg/L0.02mg/L0.1mg/L0.6mg/L)Chlorophyllaandgrowthrate

μ=(lnm2-lnm1)/(t2-t1)(everytwodays)ChlorophyllfluorescencePAMfluorescencemonitoringsystem(48h)PhotosyntheticoxygenevolutionClark-typeoxygenelectrode(48h)ThefluidityofthylakoidmembraneStatisticalanalysisMaterialsandmethodsChangesofgrowthratesandrETRmaxGrowthandrETRmax

ofM.a

wasobviously

inhibitedbylowPstatus.ResultanddiscussionChangesofrETRandΦPSⅡETRrisesignificantlywiththeincreaseofinorganic

phosphoruslevel.ResultanddiscussionqP

andqNResultanddiscussion

Theincreasingofirradiance,QA

wouldbeaccumulatedatacceptor

side,andqPdecreasedquicklyduetotheclosureofPSⅡinteractioncenters.When

lightishighenoughtobesaturating,thedecliningrateofqPwasveryslowbecauseof

mostinteractioncentersareclosedandfunctional

inactivation.1=Ft+qN+qPCalvincyclecouldremovemostoftheelectronswhichaccumulatedattheacceptorsideofPSⅡreactioncenters,leadtoQA-reoxidationandahigherqP,whichfurtherresultedinalowerqN.ResultanddiscussionTheresponseofphotosyntheticcarbonassimilationtolowPlevelResultanddiscussionTherespondingmechanismofM.aeruginosaPCC7806tolow-phosphorusResultanddiscussionResultanddiscussionConclusionM.a在P不足的條件下，生長(zhǎng)率顯著降低，ETRmax在48小時(shí)后也明顯下降,而在富P條件下，ETRmax保持上升，最后達(dá)到一個(gè)相對(duì)穩(wěn)定的值。隨著光照度的增加，ΦPSⅡ和qP明顯降低。當(dāng)P濃度從0.6mg/L降到0.02mg/L時(shí)，ETRmax的降低率明顯要比光合碳同化的比率要大。這說明由P