Plant Growth & Development (Biol 220 #4) PDF

Flux , massbalance and Control System How do plants and move? Elongation Biomass...

Flux , massbalance and Control System How do plants and move? Elongation Biomass grow Photosynthesis H20 FlUX 4 Pp) ~ W x Tw = + biomass F2 through aquaporine ~ cellular Plant cell respiration Elongated plant cell What determines Auxin - in Cell ? via AuXILAX co-transporter 20 active transport S Auxin- Plant cell > flux of auxin through PIN proteins in base of each cell  Plant Growth overview 1) sense : Light in Out 2) Auxin growth hormone in cell wall 3) Auxin growth hypothesis 4) Respond : 1) Sense : Light cell elongation directional Phototrophin growth-sensor = < membranebound blue light # # E =>Phosphorylated PHOT PHOT reversal (SIOw) How plants sense unidirectional light ~ activates Auxin growth hypothesis shade avoidence-sensor Phytochrome = canopy elongation high R : FV)1 mostly Pr : Redsgohms unshaded red : FRhigh : mostly Per signal transduction Pr per flowering I germination far red 730nm ↑ stem elongation · natural conversion due to light evening High R : Fr Per PINS move to bottom of cell bindtoreceptora elongation Of TF repressors Low R : Fr PE PINS move to side Stomata open in light close : cause relax open : water pressure pops guard cell open Guard Cells : unconnected , between cells verythick cell walls , no expansions no plasmo desmata , control over symplast 2) Auxin Growth Hormone Auxin (IAA)-growth hormone. aset ·cellswincrAuxinhave greater elongatio m cell membrane cell wall en Chlorplast (moves based on light) (Influence the direction o Auxin) Impact on H+ pump ↑ auxin in cell into nucleus : auxin + receptor bounds removes IF repression TSAUR-inhibits phosphase < proton pump activity effects ↑ H + proton pump-Acid growth hypothesis  3) Acid Growth Hypothesis "Wall cell wall extensibility looseing expansin cross-linking = polysaccharides cellwall - Cellulose m H+ H+ 2 cyto. A plasmaembrane · · Apoplast ATP HtoADP + Pi 10W H + symplast - proton pump that uses energy from ATP plant Elongation H + pump increases activity L H + out J - more negative It out generates H+ ↑ cytoplasts membrane potential the gradient for proton 1) Auxin increases activity of Proton pump flux cotransporting in W TH 2) + in apoplast cation 4 activates expansions anions FL ↳ loosen cellulose connections flux into symplast - microfibilers Slide ~ 3) ↑ wall inc solutesymplast. extensibility ↓ Ps Tw I gradient for water flux in) ~ Increased elongation rate pressure in cell) yeild threshold  Response : Cell Elongation water flux into cell water potential large solute conc More heg H20 into Cell more expansion. = = = 0 Potential Twtr plant cell larger gradient into cell * & cell membrane plant cell pumps T solute concentration ↓ solute potential symplasts k 100mM + = Apoplasts k+ = Imm Cl - = 30mM Cl - ImM cation along ATP ecg 3 ⑧ > Ht log(i mu H+ [ ⑨ 20 active transport facilitated anions diffusion solute conc.. vS. Solute Potential Volume of water vs. pressure potential T 10- drivingforce F of H20 # driving force F of H20 - 10- 8 ! volume of H2O solute conc. (in plant cell) (piant cell  Flux , massbalance blue ? and How do gaurd cells sense light and response to swelling Control System stim-blue light uptakeroots e water soil Recep-PHOT to - Input/output-signal cascade transduction - YS = - Pw target- A+ pump Response - ↑H10 uptake water plants S transpiration H20 Vapor loss through stomata what determines amount of H20 in plants? In lea uptakea fluxxylem root I ~ H20 Y transpiration H20 leaf - > transpiration rate F2 = Plant a Stomata gradient > somet what determines the amount ofH20 in xylem ? flux from roots Y L H20 - firtoe Xylem (transpirationa root Tw lower than Soil Chightolow)  Plants and Water ↑ living cells Xylem ; apoplast Xylem Air LOWRH Yo very neg = inte => transpiration vein · mesophyll cells iii atmosphere s Stoma.. cohesion Tension > ↑ H2O in Cell Walls - · Sy ↑w ↑s +4pPlasmo- = desmata Strip endodermis > water into apoplasts - T tension in xylem > - Negative potential pressure Yp cohesion-tension hypothesis : transpiration generates neg pressure potential (tension) cohension-leads to surface tension which resists curvature , tension creating ↓ neg pressure High surface tension more curve Adhesion-causes water to "stick" to other substance Gravitational potential To needed to overcome Po enough neg potential is X at xylem  Stomata gaurd cell + pore = Stoma Stomata open water flow into : gaurd cells gas exchange - loss Of H2O evaporation cooling - Guard cells control water stomata opening and closing of - Bluelight sense When opening : accumulate solutes gaurd cells - ↓ solute potential inside Twater gradient ↑ turgor pressure Phosphoralated = open , higher activity Guard cells Sense ABA at night or under waterStress Stimulates ABA production - YABA De when closing : - solutes pumped out of gaurd cell ↑ solute inside > - water exits > - ↓turgor pressure an c + H20