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Plan C We will pick a problem in plant biology and see where it takes us. Plant products Climate/CO 2 change Stress responses/stress avoidance. Plants & products chosen Capsaicin Capsicum sp. Glucosinolates Radishes ( Raphanus sativus ) Mustard ( Brassica juncea ) Alliin -> Allicin
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Plan C • We will pick a problem in plant biology and see where it takes us. • Plant products • Climate/CO2 change • Stress responses/stress avoidance
Plants & products chosen • Capsaicin • Capsicum sp. • Glucosinolates • Radishes (Raphanussativus) • Mustard(Brassica juncea) • Alliin -> Allicin • Garlic (Allium sativum)
Other candidates • Propanethial-S-oxide • Onions (Allium cepa) • Portulacanones • Purslane(Portulacaoleracea) • Allylisothiocyanate • Horseradish (Armoraciarusticana) • Wasabi (Eutremajaponicum) • eugenol (and others) • Basil (Ocimumbasilicum)
Stresses Chosen • Climate change • Temperature • Increased pCO2 • Drought • pH • Nutrient deprivation • Metal toxicity (a result of low pH) • Predation • Shaking
Course Plan • We will study effects of nutrition and stresses on plant growth and secondary products and see where it leads us • Learn about plant stress • Learn about plant nutrition • Learn about plant secondary products • Pick plants to study • Decide how to study them
Plant Stress • Won Senator Proxmire’s “Golden Fleece” award for wasteful government spending • Water? • Nutrients? • Environment? • Temp? • Pollution? • Ozone, other gases? • Herbicides, eg Round-Up, Atrazine? • Insects and other herbivores? • Pathogens = bacteria, viruses, fungi
Mineral Nutrition • Studied by soil-free culture in nutrient solutions: • Sand culture • Hydroponics: immerse roots in nutrient solution • Slanted film maintains [nutrients] &O2 • Aeroponics spraysnutrient solution on roots
Mineral Nutrition Macronutrients: CHOPKNSCaFeMg Micronutrients: BNaCl others include Cu, Zn, Mn
Mineral Nutrition • Soil nutrients • Amounts & availabilityvary • Many are immobile, eg P, Fe
Mineral Nutrition • Ectomycorrhizae surround root: only trees, esp. conifers • release nutrients into apoplast to be taken up by roots
Rhizosphere • Endomycorrhizae invade root cells: Vesicular/Arbuscular • Most angiosperms, especially in nutrient-poor soils • Deliver nutrients into symplast or release them when arbuscule dies • Also find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere
Rhizosphere • N-fixing bacteria supply N to many plant spp • Most live in root nodules & are fed & protected from O2 by plant
Nutrient uptake • Then must cross plasma membrane • Gases, small uncharged & non-polar molecules diffuse • down their ∆ [ ] • Important for CO2, auxin & NH3 transport
Nutrient uptake • Then must cross plasma membrane • Gases, small uncharged & non-polar molecules diffuse • down their ∆ [ ] • Polar chems must go through proteins!
Selective Transport 1) Channels integral membrane proteins with pore that specificionsdiffuse through
Selective Transport • 1) Channels • integral membrane proteins with pore that specificionsdiffuse through • depends on size • &charge
Channels • integral membrane proteins with pore • that specificionsdiffuse through • depends on size& charge • O in selectivity filter bind • ion (replace H2O)
Channels • integral membrane proteins with pore • that specificionsdiffuse through • depends on size& charge • O in selectivity filter bind • ion (replace H2O) • only right one fits
Channels • O in selectivity filter bind • ion (replace H2O) • only right one fits • driving force? • electrochemical D
Channels • driving force : electrochemical D • “non-saturable”
Channels • driving force : electrochemical D • “non-saturable” • regulate by opening & closing
Channels • regulate by opening & closing • ligand-gated channels open/close when bind specific chemicals
Channels • ligand-gated channels open/close when bind specific chemicals • Stress-activated channels open/close in response to mechanical stimulation
Channels Stress-activated channels open/close in response to mechanical stimulation voltage-gatedchannels 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 • Closed • Open • Inactivated
Selective Transport • 1) Channels • 2) Facilitated Diffusion (carriers) • Carrier binds molecule
Selective Transport • Facilitated Diffusion (carriers) • Carrier binds molecule • carries it through membrane • & releases it inside
Selective Transport • Facilitated Diffusion (carriers) • Carrier binds molecule • carries it through membrane • & releases it inside • driving force = ∆ [ ]
Selective Transport • Facilitated Diffusion (carriers) • Carrier binds molecule • carries it through membrane • & releases it inside • driving force = ∆ [ ] • Important for sugar • transport
Selective Transport • Facilitated Diffusion (carriers) • Characteristics • 1) saturable • 2) specific • 3) passive: transports • down ∆ []
Selective Transport 1) Channels 2) Facilitated Diffusion (carriers) Passive transport should equalize [ ] Nothing in a plant cell is at equilibrium!
Selective Transport Passive transport should equalize [ ] Nothing in a plant cell is at equilibrium! Solution: use energy to transport specific ions against their ∆ [ ]
Active Transport • Integral membrane proteins • use energy to transport specific ions against their ∆ [ ] • allow cells to concentrate some chemicals, exclude others
Active Transport Characteristics 1) saturable 105-106 ions/s 102-104 molecules/s
Active Transport Characteristics 1) saturable 2) specific
Active Transport Characteristics 1) saturable 2) specific 3) active: transport up ∆ [ ] (or ∆ Em)
4 classes of Active transport ATPase proteins • 1) 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 proteins • 1) P-type ATPases (P = “phosphorylation”) • 2) V-type ATPases (V = “vacuole”) • H+ pump in vacuoles
4 classes of Active transport ATPase proteins • 1) 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 proteins • 1) 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 proteins • 1) 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 • pump hydrophobic drugs out of cells • very broad specificity
Secondary active transport Uses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ]
Secondary active transport Uses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ] Symport:both substances pumped same way
Secondary active transport Uses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ] Symport:both substances pumped same way Antiport: substances pumped opposite ways
Secondary active transport Uses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ] Symport:both substances pumped same way Antiport: substances pumped opposite ways
Nutrient uptake Gases enter/exit by diffusion down their ∆ [ ]
Nutrient uptake Gases enter/exit by diffusion down their ∆ [ ] Ions vary dramatically!
Nutrient uptake Gases enter/exit by diffusion down their ∆ [ ] Ions vary dramatically! H+ is actively pumped out of cell by P-type H+ -ATPase
Nutrient uptake Gases enter/exit by diffusion down their ∆ [ ] Ions vary dramatically! H+ is actively pumped out of cell by P-type H+ -ATPase and into vacuole by V-type!