We will study effects of stresses on plants and see where it leads us Course Plan We will study effects of stresses on plants and see where it leads us Phytoremediation Plant products Biofuels Effects of seed spacing on seed germination Effects of nutrient deprivation Effects of stresses Climate/CO2 change Non-coding RNAs Biotechnology Plant movements: flytraps, mimosa, soybeans Carnivorous plants Stress responses/stress avoidance Plant signaling (including neurobiology) Flowering? Hormones? Plant pathology? Plant tropisms and nastic movements Root growth responses Metal toxicity? Circadian rhythms? Effects of magnetic fields? Effects of different colors of light on plant growth?

We will study effects of stresses on plants and see where it leads us Learn about plant stress Pick some stresses to study Decide which plants to study and how to assay the stress effects What to measure? Biomass Yield Proteins, pigments Secondary products Responses to stimuli Solar tracking Leaf closing Tropisms Flowering

Plant Stress Won Senator Proxmire’s “Golden Fleece” award for wasteful government spending Water? Nutrients? Environment? Temp? pCO2? Pollution? Ozone, other gases? Herbicides, eg Round-Up, Atrazine? Light? Insects and other herbivores? Pathogens = bacteria, viruses, fungi

Mineral Nutrition Studied by soil-free culture in nutrient solutions:

Mineral Nutrition Soil-free culture Sand culture Hydroponics: immerse roots in nutrient solution Slanted film maintains [nutrients] & O2 Aeroponics sprays nutrient solution on roots

Mineral Nutrition Macronutrients CHOPKNS CHOPNS make biopolymers

Mineral Nutrition Macronutrients CHOPNS make biopolymers N deficiency mobile in plant, so old leaves go yellow first

Mineral Nutrition P deficiency mobile in plant, so shows first in old leaves which turn dark green or purple

Mineral Nutrition S deficiency mobile in plant, so shows first in old leaves which turn yellow

Mineral Nutrition K deficiency mobile in plant, so shows first in old leaves which go yellow at edges.

Mineral Nutrition Ca deficiency immobile in plant, so shows first in young leaves which show blotches of necrotic tissue Crucial role in water- splitting!

Mineral Nutrition Fe deficiency immobile in plant, so shows first in young leaves which turn yellow while veins stay green

Mineral Nutrition Mg deficieincy mobile in plant, so shows first in old leaves which brown off at edges

Mineral Nutrition Mg deficieincy mobile in plant, so shows first in old leaves which brown off at edges One/ chlorophyll and also cofactor for many enzymes

Mineral Nutrition Micronutrients: BNaCl B: cell elongation. NA metabolism immobile in plant, so shows first in young leaves

Mineral Nutrition Micronutrients: BNaCl B: cell elongation. NA metabolism Na: PEP regeneration in C4, K substitute mobile in plant, so shows first in old leaves

Mineral Nutrition Micronutrients: BNaCl B: cell elongation. NA metabolism Na: PEP regenerationin C4, K substitute Cl: water-splitting, osmotic balance 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

Mineral Nutrition Micronutrients: BNaCl others include Cu, Zn, Mn Mn: cofactor for many enzymes, especially water splitting enzyme Immobile in plants so shows first in young leaves

Mineral Nutrition Commercial fertilizers mainly supply NPK

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%)

Nutrient excesses More infrequent since plants control nutrient uptake

Nutrient excesses More infrequent since plants control nutrient uptake Na stress: frequently occurs in areas that have been irrigated or are near oceans

Effects of excess Sodium Reduced turgor due to lower Ys Reduced growth rate Plasmolysis

Effects of excess Sodium Reduced turgor due to lower Ys Enzyme inhibition [Na] > 100 mM inhibit enzymes of all spp Even spp that live in 5 M NaCl

Effects of excess Sodium Reduced turgor due to lower Ys Enzyme inhibition Accumulation in old leaves to toxic levels

Mechanisms of Sodium Tolerance Exclusion negative correlation with HKT1 (unloads Na from xylem)and salt tolerance in Arabidopsis Accumulation of Na+ in leaf promotes Na tolerance!

Mechanisms of Sodium Tolerance Exclusion Compartmentalization in vacuoles Some plants make salt glands that excrete salt

Mechanisms of Sodium Tolerance Exclusion Compartmentalization in vacuoles Osmotic tolerance Mechs not fully understood; sometimes involve accumulation of organics such as trehalose in vacuole Reason weak HKT1 promotes Na tolerance?

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

Rhizosphere N-fixing bacteria supply N to many plant spp Most live in root nodules & are fed & protected from O2 by plant

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

Selective Crossing membranes A) Diffusion through bilayer B) Difusion through protein pore C) Facilitated diffusion D) Active transport E) Bulk transport 1) Exocytosis 2) Endocytosis Selective Active

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 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!

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

Nutrient uptake Ca2+ is expelled by P-type ATPases in PM pumped into vacuole & ER by H+ antiport & P-type enters cytosol via gated channels

Nutrient uptake PO43-, SO42-, Cl- & NO3- enter by H+ symport

Nutrient uptake PO43-, SO42-, Cl- & NO3- enter by H+ symport also have anion transporters of ABC type

Nutrient uptake PO43-, SO42-, Cl- & NO3- enter by H+ symport also have anion transporters of ABC type and anion channels

Nutrient uptake PO43-, SO42-, Cl- & NO3- enter by H+ symport also have anion transporters of ABC type and anion channels Plants take up N many ways

Nutrient uptake Plants take up N many ways: NO3- & NH4+ are main forms

Nutrient uptake Plants take up N many other ways NO3- also by channels NH3 by diffusion NH4+ by carriers

Nutrient uptake Plants take up N many other ways NO3- by channels NH3 by diffusion NH4+ by carriers NH4+ by channels

Nutrient uptake Plants take up N many other ways 3 families of H+ symporters take up amino acids

Nutrient uptake Plants take up N many other ways 3 families of H+ symporters take up amino acids Also have many peptide transporters some take up di- & tri- peptides by H+ symport

Nutrient uptake Plants take up N many other ways 3 families of H+ symporters take up amino acids Also have many peptide transporters some take up di- & tri- peptides by H+ symport others take up tetra- & penta-peptides by H+ symport

Nutrient uptake Plants take up N many other ways 3 families of H+ symporters take up amino acids Also have many peptide transporters some take up di- & tri- peptides by H+ symport others take up tetra- & penta-peptides by H+ symport Also have ABC transporters that import peptides

Nutrient uptake Plants take up N many other ways 3 families of H+ symporters take up amino acids Also have many peptide transporters some take up di- & tri- peptides by H+ symport others take up tetra- & penta-peptides by H+ symport Also have ABC transporters that import peptides N is vital! NO3- & NH4+ are main forms

Nutrient uptake Metals are taken up by ZIP proteins & by ABC transporters same protein may import Fe, Zn & Mn!

Nutrient uptake Much is coupled to pH gradient

Nutrient transport in roots Move from soil to endodermis in apoplast

Nutrient transport in roots Move from soil to endodermis in apoplast Move from endodermis to xylem in symplast

Nutrient transport in roots Move from endodermis to xylem in symplast Transported into xylem by H+ antiporters

Nutrient transport in roots Move from endodermis to xylem in symplast Transported into xylem by H+ antiporters, channels

Nutrient transport in roots Transported into xylem by H+ antiporters, channels,pumps

Nutrient transport in roots Transported into xylem by H+ antiporters, channels,pumps Lowers xylem water potential -> root pressure

Transport to shoot Nutrients move up plant in xylem sap

Nutrient transport in leaves Xylem sap moves through apoplast Leaf cells take up what they want