course plan we will study effects of soil and stresses on plant secondary products and see where it...
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Course PlanWe will study effects of soil and stresses on plant secondary products and see where it leads us1.Learn more about plant secondary products•Why do they make them?•When do they make them?•Where do they make them?
Pick some plants to study•Capsicum (Chiles) = capsaicin•Nicotiana (Tobacco) = nicotine•Onions (Allium cepa)?= syn-Propanethial-S-oxide•Garlic (Allium sativum)?= Alliin•Radishes (Raphanus sativus) = glucosinolates•Mustard (Brassica juncea) = glucosinolates•Basil (Ocimum basilicum) = eugenol (and others)•Cilantro (Coriandrum sativum) = lots of candidates!•Peppermint (Mentha × piperita) = menthol + many•Catnip (Nepeta cataria) = nepetalactone•Dill = dillapiole•Purslane (Portulaca oleracea)= omega-3 fatty acids•Brassica rapa = glucosinolates
Plant StressWon Senator Proxmire’s “Golden Fleece” award for wasteful government spending1.Water?2.Nutrients?3.Environment?• Temp?• Pollution?• Ozone, other gases?• Herbicides, eg Round-Up, Atrazine?
• Insects and other herbivores? • Pathogens = bacteria, viruses, fungi
Plant StressNext assignment: presenting a plant stressor, what is known about it, and why it might affect plant 2˚ compounds in an ~ 10 minute presentation?
Alternative: presenting another good plant/stressor response to study and why we should choose it over the ones already presented.
Mineral NutritionMacronutrients: CHOPKNSCaFeMgBNaCl
• Ca: signaling, middle lamella, cofactor• Fe: cofactor• Mg: cofactor• mobile in plant, so shows first in old leaves
Mineral NutritionMicronutrients: BNaCl others include Cu, Zn, Mn
• B: cell elongation. NA metabolism• Na: PEP regeneration, K substitute• Cl: water-splitting, osmotic balance• Cu: cofactor• immobile in plant, so shows first in young leaves
Plant food• 2.6% ammoniacal nitrogen • 4.4% nitrate nitrogen• 9% phosphorus• 5% potassium• calcium (2%)• magnesium (0.5%)• sulfur (0.05%)• boron (0.02%)• chlorine (0.1%)• cobalt (0.0015%)• copper (0.05%)• iron (0.1%)• manganese (0.05%)• molybdenum (0.0009%)• nickel (0.0001%)• sodium (0.10%) • zinc (0.05%)
Mineral NutritionSoil nutrients•Amounts & availability varyPSU extension Text
Mineral NutritionSoil nutrients•Amounts & availability vary•Many are immobile, eg P, Fe
Mineral NutritionSoil nutrients• Amounts & availability vary• Many are immobile, eg P, Fe• Mobile nutrients come with soil H2O
Mineral NutritionSoil nutrients• Amounts & availability vary• Many are immobile, eg P, Fe• Mobile nutrients come with soil H2O
• Immobiles must be “mined”• Root hairs get close
Mineral NutritionImmobile nutrients must be “mined”
• Root hairs get close• Mycorrhizae get closer
Mineral NutritionImmobile nutrients must be mined
• Root hairs get close• Mycorrhizae get closer
Solubility varies w pH
Mineral Nutrition•Solubility varies w pH•5.5 is best compromise
Mineral NutritionSolubility varies w pH•5.5 is best compromise•Plants alter pH @ roots to
aid uptake
Mineral NutritionNutrients in soil•Plants alter pH @ roots to aid uptake• Also use symbionts
• Mycorrhizal fungi help: especially with P
Mineral NutritionAlso use symbionts•Mycorrhizal fungi help: especially with P• P travels poorly: fungal hyphae are longer & thinner
Mineral NutritionAlso use symbionts•Mycorrhizal fungi help: especially with P• P travels poorly: fungal hyphae are longer & thinner
• Fungi give plants nutrients
Mineral NutritionAlso use symbionts•Mycorrhizal fungi help: especially with P• P travels poorly: fungal hyphae are longer & thinner
• Fungi give plants nutrients• Plants feed them sugar
Mineral NutritionAlso use symbionts•Mycorrhizal fungi help: especially with P• P travels poorly: fungal hyphae are longer & thinner
• Fungi give plants nutrients• Plants feed them sugar
• Ectomycorrhizae surround root: only trees, esp. conifers
Mineral NutritionEctomycorrhizae surround root: only trees, esp. conifers• release nutrients into apoplast to be taken up by roots
Mineral NutritionEctomycorrhizae surround root: trees•release nutrients into apoplast to be taken up by rootsEndomycorrhizae invade root cells: Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor soils
Mineral NutritionEndomycorrhizae invade root cells: Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor soils• May deliver nutrients into symplast
RhizosphereEndomycorrhizae invade root cells: Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor soils• May deliver nutrients into symplast• Or may release them when arbuscule dies
RhizosphereEndomycorrhizae invade root cells: Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor soils• Deliver nutrients into symplast or release them
when arbuscule diesAlso find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere
RhizosphereAlso find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere• Plants feed them lots of C!
RhizosphereAlso find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere• Plants feed them lots of C!• They help make nutrients available
RhizosphereAlso find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere• Plants feed them lots of C!• They help make nutrients available• N-fixing bacteria supply N to many plant spp
N assimilation by N fixersExclusively performed by prokaryotesDramatically improve the growth of many plants
N assimilation by N fixersExclusively done by prokaryotesMost are free-living in soil or water
N assimilation by N fixersExclusively done by prokaryotesMost are free-living in soil or waterSome form symbioses with plants
N assimilation by N fixersExclusively done by prokaryotesMost are free-living in soil or waterSome form symbioses with plantsLegumes are best-known, butmany others including mosses,ferns, lichens
N assimilation by N fixersExclusively done by prokaryotesMost are free-living in soil or waterSome form symbioses with plantsLegumes are best-known, butmany others including mosses,ferns, lichensAlso have associations where N-fixers form films on leaves orroots and are fed by plant
N assimilation by N fixersExclusively done by prokaryotesAlso have associations where N-fixers form films on leaves orroots and are fed by plantAll must form O2-free environment for nitrogenase
N assimilation by N fixersAll must form O2-free environment for nitrogenaseO2 binds & inactivates electron-transfer sites
N assimilation by N fixersO2 binds & inactivates electron-transfer sitesHeterocysts lack PSII, haveother mechs to lower O2
N assimilation by N fixersHeterocysts lack PSII, haveother mechs to lower O2 Nodules have specialstructure + leghemoglobinto protect from O2
Nodule formationNodules have special structure + leghemoglobin to protect
from O2 Bacteria induce the plant to form nodules
Nodule formationBacteria induce the plant to form nodules1. Root hairs secrete chemicals that attract N-fixers
Nodule formationBacteria induce the plant to form nodules1. Root hairs secrete chemicals that attract N-fixers2. Bacteria secrete Nod factors that induce root hair to
coil up. Nod factors determine species-specificity
Nodule formation1. Root hairs secrete chemicals that attract N-fixers2. Bacteria secrete Nod factors that induce root hair to
coil up. Nod factors determine species-specificity3. Nod factors induce degradation of root cell wall
Nodule formation3. Nod factors induce degradation of root cell wall4. Plant forms "infection thread"=internal protusion of
plasma membrane that grows into cell5. When reaches end of cell bacteria are released into
apoplast and repeat the process on inner cells
Nodule formation5. When reaches end of cell bacteria are released into
apoplast and repeat the process on inner cells6. Cortical cells near xylem form a nodule primordium
Nodule formation5. When reaches end of cell bacteria are released into
apoplast and repeat the process on inner cells6. Cortical cells near xylem form a nodule primordium7. When bacteria reach these cells the infection thread
breaks off, forming vesicles with bacteria inside
Nodule formation7. When bacteria reach these cells the infection thread
breaks off, forming vesicles with bacteria inside8. Vesicles fuse, form the peribacteroid membrane and
bacteria differentiate into bacteroids.
Nodule formation8. Vesicles fuse, form the peribacteroid membrane and
bacteria differentiate into bacteroids.9. Plant cells differentiate into nodules
Nodule formation8. Vesicles fuse, form the peribacteroid membrane and
bacteria differentiate into bacteroids.9. Plant cells differentiate into nodules: have layer of cells
to exclude O2 & vasculatureto exchange nutrients
Nodule formationPlant cells differentiate into nodules: have layer of cells to
exclude O2 & vasculature to exchange nutrientsComplex process that is difficult to engineer: 21 non-
legume plant genera have N-fixers
Nitrogen fixationN2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Catalysed by nitrogenase, a very complex enzyme!
Nitrogen fixationN2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Catalysed by nitrogenase, a very complex enzyme!Also catalyzes many other reactionsUsually assayed by acetylene reduction
Nitrogen fixationN2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Usually assayed by acetylene reductionSequentially adds 2 H per cycle until reach NH3
Nitrogen fixationSequentially adds 2 H per cycle until reach NH3
May then be exported to cytosol & assimilated by GS/GOGAT or assimilated inside bacteroid
Nitrogen fixationSequentially adds 2 H per cycle until reach NH3
May then be exported to cytosol & assimilated by GS/GOGAT or assimilated inside bacteroidAre then converted to amides or ureides& exported to rest of plant in the xylem!
Nutrient uptakeMost nutrients are dissolved in water
Nutrient uptakeMost nutrients are dissolved in water
• Enter root through apoplast until hit endodermis
Nutrient uptakeMost nutrients are dissolved in water
• Enter root through apoplast until hit endodermis• Then must cross plasma membrane
Crossing membranesA) Diffusion through bilayer B) Difusion through protein poreC) Facilitated diffusionD) Active transportE) Bulk transport
1) Exocytosis2) Endocytosis
Selective
Active
Nutrient uptakeThen must cross plasma membrane
• Gases, small uncharged & non-polar molecules diffuse
Nutrient uptakeThen must cross plasma membrane
• Gases, small uncharged & non-polar molecules diffusedown their ∆ [ ]• Important for CO2, auxin & NH3 transport
Nutrient uptakeThen must cross plasma membrane
• Gases, small uncharged & non-polar molecules diffusedown their ∆ [ ]• Polar chems must go through proteins!
Selective Transport
1) Channels
integral membrane proteins with pore that specific ions diffuse through
Selective Transport
1) Channels
integral membrane proteins with pore that specific ions diffuse through• depends on size & charge
Channelsintegral membrane proteins with pore that specific ions diffuse through• depends on size & charge• O in selectivity filter bindion (replace H2O)
Channelsintegral membrane proteins with pore that specific ions diffuse through• depends on size & charge• O in selectivity filter bindion (replace H2O)• only right one fits
ChannelsO in selectivity filter bindion (replace H2O)• only right one fits• driving force?electrochemical
Channelsdriving force : electrochemical “non-saturable”
Channelsdriving force : electrochemical “non-saturable”regulate by opening & closing
Channelsregulate by opening & closingligand-gated channels open/close when bind specific chemicals
Channelsligand-gated channels open/close when bind specific chemicalsStress-activated channels open/close in response to mechanical stimulation
ChannelsStress-activated channels open/close in response to mechanical stimulationvoltage-gated channels open/close in response to changes in electrical potential
Channels• Old model: S4 slides up/down• Paddle model: S4 rotates
Channels• Old model: S4 slides up/down• Paddle model: S4 rotates• 3 states
1.Closed2.Open3. Inactivated
Selective Transport1) Channels2) Facilitated Diffusion (carriers)
Carrier binds molecule
Selective TransportFacilitated Diffusion (carriers)
Carrier binds moleculecarries it through membrane& releases it inside
Selective TransportFacilitated Diffusion (carriers)
Carrier binds moleculecarries it through membrane& releases it insidedriving force = ∆ [ ]
Selective TransportFacilitated Diffusion (carriers)
Carrier binds moleculecarries it through membrane& releases it insidedriving force = ∆ [ ]Important for sugar transport
Selective TransportFacilitated Diffusion (carriers)Characteristics
1) saturable 2) specific 3) passive: transports down ∆ []
Selective Transport1) Channels2) Facilitated Diffusion (carriers)Passive transport should equalize [ ]Nothing in a plant cell is at equilibrium!
Selective TransportPassive transport should equalize [ ]Nothing in a plant cell is at equilibrium!Solution: use energy to transport specific ions against their ∆ [ ]
Active TransportIntegral membrane proteins • use energy to transport specific ions against their ∆ [ ]• allow cells to concentrate some chemicals, exclude others
Active TransportCharacteristics1) saturable
102-104 molecules/s105-106 ions/s
Active TransportCharacteristics1) saturable2) specific
Active TransportCharacteristics1) saturable2) specific
3) active: transport up ∆ [ ] (or ∆ Em)
4 classes of Active transport ATPase proteins1) P-type ATPases (P = “phosphorylation”)
• Na/K pump• Ca pump in ER & PM• H+ pump in PM
• pumps H+ out of cell
4 classes of Active transport ATPase proteins1) P-type ATPases (P = “phosphorylation”)2) V-type ATPases (V = “vacuole”)
• H+ pump in vacuoles
4 classes of Active transport ATPase proteins1) P-type ATPases (P = “phosphorylation”)2) V-type ATPases (V=“vacuole”)3) F-type ATPases (F = “factor”) a.k.a. ATP synthases
• mitochondrial ATP synthase• chloroplast ATP synthase
4 classes of Active transport ATPase proteins1) P-type ATPases (P = “phosphorylation”)2) V-type ATPases (V = “vacuole”)3) F-type ATPases (F = “factor”)4) ABC ATPases (ABC = “ATP Binding Cassette”)
• multidrug resistance proteins
4 classes of Active transport ATPase proteins1) P-type ATPases (P = “phosphorylation”)2) V-type ATPases (V = “vacuole”)3) F-type ATPases (F = “factor”)4) ABC ATPases (ABC = “ATP Binding Cassette”)
• multidrug resistance proteinspump hydrophobic drugs out of cellsvery broad specificity
Secondary active transportUses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ]
Secondary active transportUses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ] Symport: both substances pumped same way
Secondary active transportUses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ] Symport: both substances pumped same wayAntiport: substances pumped opposite ways
Secondary active transportUses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ] Symport: both substances pumped same wayAntiport: substances pumped opposite ways
Nutrient uptakeGases enter/exit by diffusion down their ∆ [ ]
Nutrient uptakeGases enter/exit by diffusion down their ∆ [ ]Ions vary dramatically!
Nutrient uptakeGases enter/exit by diffusion down their ∆ [ ]Ions vary dramatically!H+ is actively pumped out of cell by P-type H+ -ATPase
Nutrient uptakeGases enter/exit by diffusion down their ∆ [ ]Ions vary dramatically!H+ is actively pumped out of cell by P-type H+ -ATPaseand into vacuole by V-type!
Nutrient uptakeH+ is actively pumped out of cell by P-type H+ -ATPaseand into vacuole by V-type!• Main way plants make membrane potential (∆Em)!
Nutrient uptakeH+ is actively pumped out of cell by P-type H+ -ATPaseand into vacuole by V-type!• Main way plants make membrane potential (∆Em)!• K+ diffuses through channels down ∆Em
Nutrient uptake• K+ diffuses through channels down ∆Em• Also taken up by transporters
Nutrient uptake• K+ diffuses through channels down ∆Em• Also taken up by transporters
• some also transport Na+
Nutrient uptake• K+ diffuses through channels down ∆Em• Also taken up by transporters
• some also transport Na+
• why Na+ slows K+ uptake?
Nutrient uptake• K+ diffuses through channels down ∆Em• Also taken up by transporters
• some also transport Na+
• why Na+ slows K+ uptake?
Na+ is also expelled by H+ antiport
Nutrient uptake• K+ diffuses through channels down ∆Em• Also taken up by transporters
• some also transport Na+
• why Na+ slows K+ uptake?
Na+ is also expelled by H+ antiport•Enters through channels
Nutrient uptakeNa+ is also expelled by H+ antiport•Enters through channelsCa2+ is expelled by P-typeATPases in PM
Nutrient uptakeNa+ is also expelled by H+ antiport•Enters through channelsCa2+ is expelled by P-typeATPases in PM& pumped into vacuole by H+ antiport
Nutrient uptakeNa+ is also expelled by H+ antiport•Enters through channelsCa2+ is expelled by P-typeATPases in PM& pumped into vacuole by H+ antiport• enters cytosol via channelsPO4, SO4, Cl & NO3 enter by H+ symport
Nutrient uptakePO4, SO4, Cl & NO3 enter by H+ symport• also have anion channels of ABC type