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Course Plan We will study effects of soil and stresses on plant secondary products and see where it leads us 1. 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 Stress Won Senator Proxmire’s “Golden Fleece” award for wasteful government spending 1.Water? 2.Nutrients? 3.Environment? • Temp? • Pollution? • Ozone, other gases? • Herbicides, eg Round-Up, Atrazine? • Insects and other herbivores? • Pathogens = bacteria, viruses, fungi Plant Stress Next 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 Nutrition Macronutrients: CHOPKNSCaFeMgBNaCl • Ca: signaling, middle lamella, cofactor • Fe: cofactor • Mg: cofactor • mobile in plant, so shows first in old leaves Mineral Nutrition Micronutrients: 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 Nutrition Soil nutrients •Amounts & availability vary PSU extension Text Mineral Nutrition Soil nutrients •Amounts & availability vary •Many are immobile, eg P, Fe Mineral Nutrition Soil nutrients • Amounts & availability vary • Many are immobile, eg P, Fe • Mobile nutrients come with soil H2O Mineral Nutrition Soil 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 Nutrition Immobile nutrients must be “mined” • Root hairs get close • Mycorrhizae get closer Mineral Nutrition Immobile 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 Nutrition Solubility varies w pH •5.5 is best compromise •Plants alter pH @ roots to aid uptake Mineral Nutrition Nutrients in soil •Plants alter pH @ roots to aid uptake • Also use symbionts • Mycorrhizal fungi help: especially with P Mineral Nutrition Also use symbionts •Mycorrhizal fungi help: especially with P • P travels poorly: fungal hyphae are longer & thinner Mineral Nutrition Also use symbionts •Mycorrhizal fungi help: especially with P • P travels poorly: fungal hyphae are longer & thinner • Fungi give plants nutrients Mineral Nutrition Also 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 Nutrition Also 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 Nutrition Ectomycorrhizae surround root: only trees, esp. conifers • release nutrients into apoplast to be taken up by roots Mineral Nutrition Ectomycorrhizae surround root: trees •release nutrients into apoplast to be taken up by roots Endomycorrhizae invade root cells: Vesicular/Arbuscular • Most angiosperms, especially in nutrient-poor soils Mineral Nutrition Endomycorrhizae invade root cells: Vesicular/Arbuscular • Most angiosperms, especially in nutrient-poor soils • May deliver nutrients into symplast Rhizosphere Endomycorrhizae invade root cells: Vesicular/Arbuscular • Most angiosperms, especially in nutrient-poor soils • May deliver nutrients into symplast • Or may release them when arbuscule dies 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 Also find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere • Plants feed them lots of C! Rhizosphere Also find bacteria, actinomycetes, protozoa associated with root surface = rhizosphere • Plants feed them lots of C! • They help make nutrients available Rhizosphere Also 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 fixers Exclusively performed by prokaryotes Dramatically improve the growth of many plants N assimilation by N fixers Exclusively done by prokaryotes Most are free-living in soil or water N assimilation by N fixers Exclusively done by prokaryotes Most are free-living in soil or water Some form symbioses with plants N assimilation by N fixers Exclusively done by prokaryotes Most are free-living in soil or water Some form symbioses with plants Legumes are best-known, but many others including mosses, ferns, lichens N assimilation by N fixers Exclusively done by prokaryotes Most are free-living in soil or water Some form symbioses with plants Legumes are best-known, but many others including mosses, ferns, lichens Also have associations where N-fixers form films on leaves or roots and are fed by plant N assimilation by N fixers Exclusively done by prokaryotes Also have associations where N-fixers form films on leaves or roots and are fed by plant All must form O2-free environment for nitrogenase N assimilation by N fixers All must form O2-free environment for nitrogenase O2 binds & inactivates electron -transfer sites N assimilation by N fixers O2 binds & inactivates electron -transfer sites Heterocysts lack PSII, have other mechs to lower O2 N assimilation by N fixers Heterocysts lack PSII, have other mechs to lower O2 Nodules have special structure + leghemoglobin to protect from O2 Nodule formation Nodules have special structure + leghemoglobin to protect from O2 Bacteria induce the plant to form nodules Nodule formation Bacteria induce the plant to form nodules 1. Root hairs secrete chemicals that attract N-fixers Nodule formation Bacteria induce the plant to form nodules 1. Root hairs secrete chemicals that attract N-fixers 2. Bacteria secrete Nod factors that induce root hair to coil up. Nod factors determine species-specificity Nodule formation 1. Root hairs secrete chemicals that attract N-fixers 2. Bacteria secrete Nod factors that induce root hair to coil up. Nod factors determine species-specificity 3. Nod factors induce degradation of root cell wall Nodule formation 3. Nod factors induce degradation of root cell wall 4. Plant forms "infection thread"=internal protusion of plasma membrane that grows into cell 5. When reaches end of cell bacteria are released into apoplast and repeat the process on inner cells Nodule formation 5. When reaches end of cell bacteria are released into apoplast and repeat the process on inner cells 6. Cortical cells near xylem form a nodule primordium Nodule formation 5. When reaches end of cell bacteria are released into apoplast and repeat the process on inner cells 6. Cortical cells near xylem form a nodule primordium 7. When bacteria reach these cells the infection thread breaks off, forming vesicles with bacteria inside Nodule formation 7. When bacteria reach these cells the infection thread breaks off, forming vesicles with bacteria inside 8. Vesicles fuse, form the peribacteroid membrane and bacteria differentiate into bacteroids. Nodule formation 8. Vesicles fuse, form the peribacteroid membrane and bacteria differentiate into bacteroids. 9. Plant cells differentiate into nodules Nodule formation 8. Vesicles fuse, form the peribacteroid membrane and bacteria differentiate into bacteroids. 9. Plant cells differentiate into nodules: have layer of cells to exclude O2 & vasculature to exchange nutrients Nodule formation Plant cells differentiate into nodules: have layer of cells to exclude O2 & vasculature to exchange nutrients Complex process that is difficult to engineer: 21 nonlegume plant genera have N-fixers Nitrogen fixation N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi Catalysed by nitrogenase, a very complex enzyme! Nitrogen fixation N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi Catalysed by nitrogenase, a very complex enzyme! Also catalyzes many other reactions Usually assayed by acetylene reduction Nitrogen fixation N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi Usually assayed by acetylene reduction Sequentially adds 2 H per cycle until reach NH3 Nitrogen fixation Sequentially adds 2 H per cycle until reach NH3 May then be exported to cytosol & assimilated by GS/GOGAT or assimilated inside bacteroid Nitrogen fixation Sequentially adds 2 H per cycle until reach NH3 May then be exported to cytosol & assimilated by GS/GOGAT or assimilated inside bacteroid Are then converted to amides or ureides & exported to rest of plant in the xylem! Nutrient uptake Most nutrients are dissolved in water Nutrient uptake Most nutrients are dissolved in water • Enter root through apoplast until hit endodermis Nutrient uptake Most nutrients are dissolved in water • Enter root through apoplast until hit endodermis • Then must cross plasma membrane Crossing membranes A) Diffusion through bilayer B) Difusion through protein pore Selective C) Facilitated diffusion D) Active transport E) Bulk transport Active 1) Exocytosis 2) Endocytosis Nutrient uptake Then must cross plasma membrane • Gases, small uncharged & non-polar molecules diffuse 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 specific ions diffuse through Selective Transport 1) Channels integral membrane proteins with pore that specific ions diffuse through • depends on size & charge Channels integral membrane proteins with pore that specific ions diffuse through • depends on size & charge • O in selectivity filter bind ion (replace H2O) Channels integral membrane proteins with pore that specific ions diffuse 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-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.Closed 2.Open 3. 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! Nutrient uptake H+ is actively pumped out of cell by P-type H+ -ATPase and into vacuole by V-type! • Main way plants make membrane potential (∆Em)! Nutrient uptake H+ is actively pumped out of cell by P-type H+ -ATPase and 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 uptake Na+ is also expelled by H+ antiport •Enters through channels Ca2+ is expelled by P-type ATPases in PM Nutrient uptake Na+ is also expelled by H+ antiport •Enters through channels Ca2+ is expelled by P-type ATPases in PM & pumped into vacuole by H+ antiport Nutrient uptake Na+ is also expelled by H+ antiport •Enters through channels Ca2+ is expelled by P-type ATPases in PM & pumped into vacuole by H+ antiport • enters cytosol via channels PO4, SO4, Cl & NO3 enter by H+ symport Nutrient uptake PO4, SO4, Cl & NO3 enter by H+ symport • also have anion channels of ABC type