Mineral Nutrition

Macronutrients

N, P, K, Ca, Mg, S

Micronutrients

Fe, B, Mn, Zn, Cu, Ni, Mo, Cl, Na

Silicon (Si): macro or micro?

Sometimes counted as a macro

Where do C, H, O come from?

CO2 and water (not minerals)

Nutrients that are part of carbon compounds

Group 1: N, S

Nutrients that are important in energy storage or structural integrity

Group 2: B, P, Si

Nutrients that remain in ionic form

Group 3: Ca, Cl, K, Mg, Mn, Na

Nutrients that are involved in redox reactions

Group 4: Cu, Fe, Mo, Ni, Zn

Nitrogen Role

Part of amino acids, amides, proteins, nucleic acids, nucleotides, coenzymes

Sulfur Role

Part of cysteine, cystine, methionine, and proteins; coenzyme A, glutathione

Phosphorus Role

Part of sugar phosphates, nucleic acids, nucleotides, coenzymes, phospholipids, phytic acid; key role in ATP reactions

Silicon Role

Amorphous silica in cell walls; rigidity and elasticity

Boron Role

Complexes with cell wall constituents (mannitol, mannan); cell elongation; nucleic acid metabolism

Potassium Role

Cofactor for 40+ enzymes; cell turgor; electroneutrality

Calcium Role

Middle lamella of cell walls

cofactor (ATP and phospholipid hydrolysis)

second messenger in metabolic regulation

Magnesium Role

Constituent of chlorophyll

enzymes in phosphate transfer

Chlorine Role

Photosynthetic reactions involved in O2 evolution

Manganese Role

Activates dehydrogenases, decarboxylases, kinases, oxidases, peroxidases

involved in photosynthetic O2 evolution

Sodium Role

Regenerates PEP in C4 and CAM plants

substitutes for K

Iron Role

Constituent of cytochromes and nonheme iron proteins involved in photosynthesis, N2 fixation, and respiration

Zinc Role

Constituent of alcohol dehydrogenase, glutamic dehydrogenase, carbonic anhydrase

Copper Role

Plastocyanin, cytochrome oxidase, ascorbic acid oxidase, laccase

Nickel Role

Urease

hydrogenases in N2-fixing bacteria

Molybdenum Role

Part of nitrate reductase and nitrogenase, the enzymes the plant needs to use nitrogen

Enzyme that fixes N2

Nitrogenase (contains Fe and Mo)

Electron carrier containing Cu

Plastocyanin

Nutrient at the center of chlorophyll

Mg

Two nutrients needed for O2 evolution

Cl and Mn

Nutrient that acts as a second messenger

Ca

Where is calcium pectate found?

Middle lamella

Cofactor for 40+ enzymes

K

What happens when K+ moves INTO guard cells?

Stomata open

What happens when K+ moves OUT of guard cells?

Stomata close

Nutrient that can substitute for K

Na

A legume low in Fe or Mo shows what deficiency?

N deficiency (can't fix N)

Cofactor

Mineral (e.g., K, Mg, Zn) that switches an enzyme on

Comes out unchanged

Coenzyme

Organic helper (vitamins, NAD) that switches an enzyme on

Gets changed in the reaction

Is a nutrient deficiency a disease or a disorder?

Disorder (abiotic), not a disease

Mobile nutrients

N, P, K, Mg

Immobile nutrients

Ca, S, Fe, Mn, Zn, Cu, Mo, B

Where do MOBILE nutrient symptoms appear first?

Older leaves

Where do IMMOBILE nutrient symptoms appear first?

Younger leaves

Mycorrhiza

Fungus-root mutualism

Myco / rhiza

Fungus / root

Mycorrhization

Process of forming a mycorrhiza

Hyphae

Fine tube-shaped fungal filaments

In a mycorrhiza, what does the fungus give the plant?

Water and nutrients

In a mycorrhiza, what does the plant give the fungus?

Sugars (carbon)

Mycorrhizal benefits (list all 4)

1. Nutrient uptake; 2. Water/drought tolerance; 3. Pathogen protection; 4. Salinity/alkalinity tolerance

Which nutrients do mycorrhizae help take up?

Phosphate, nitrate, K, Zn, Cu

Main nutrient mycorrhizae help take up

Phosphate

How do mycorrhizae help plants during drought?

Improve water uptake and drought tolerance

How do mycorrhizae help against disease?

Protect roots from soil-borne pathogens

How do mycorrhizae help with soil stress?

Tolerance to salinity (salty soil) and alkalinity (high pH)

Two main types of mycorrhizae

Ecto and endo

Where do ectomycorrhizae grow?

Outside the root, between cells

Where do endomycorrhizae grow?

Inside cortical cells

VAM

Vesicular-arbuscular mycorrhizae (endo)

Mantle

Ecto: fungal sheath around the root

Hartig net

Ecto: hyphae between cortical cells

Arbuscules

Endo: branched hyphae in cells; nutrient exchange

Vesicles

Endo: store fungal food reserves

Hyphopodium

Endo: pad the fungus uses to enter root

Chlamydospore

Endo: protective resting spore; survives harsh conditions

Strigolactones

Root signals that trigger spore germination

Fungal sheath

Another name for the mantle

Ecto structures

Mantle, Hartig net

Endo structures

Arbuscules, vesicles, hyphopodium

Which mycorrhiza type forms mushrooms?

Ecto

Which type is found in ~80% of plants?

Endo (VAM)

Which type is found in ~3% of plants?

Ecto

What plants host ectomycorrhizae?

Trees (e.g., pine)

What plants host endomycorrhizae?

Most crops (corn, tomato)

How do endo fungi enter the root?

Through the epidermis or root hairs

What do collapsed arbuscules mean?

Association is mature or dying

Ecto fungal mass can equal what?

The root's mass

Ecto mushroom examples

Truffles, porcini, chanterelles

Mushrooms on a dying tree are likely what?

A pathogen (Armillaria)

% of dicots / monocots that form mycorrhizae

83% / 79%

Other mycorrhiza types

Ectendo, orchid, ericoid, arbutoid, monotropoid

Ericoid mycorrhizae example host

Cranberries

Ectendo mycorrhizae

Mix of ecto and endo

Which fungal groups do ecto mushrooms belong to?

Ascomycota and Basidiomycota

Three ways plants get nutrients

Soil solution, cation exchange, microbes

How do anions (e.g., nitrate) reach the root?

Bulk flow in soil solution

Why do anions stay in soil solution?

Repelled by negatively charged clay

What holds cations (K+, Ca2+, Mg2+) in soil?

Negatively charged clay

Cation exchange

Root releases H+ to free cations from clay

Cation exchange capacity (CEC)

Soil's ability to exchange cations

What does phosphate bind to in soil?

Fe, Al, or Ca

Best soil pH for nutrients

5.5 to 6.5

Below what pH are few nutrients available?

5

Which nutrients are less available above pH 7?

P, K, Mn, B, Mg, Fe, Zn

Which nutrient is MORE available in alkaline soil?

Mo

Which nutrients are MORE available in acidic soil?

Zn and Mn

Where on the root is phosphate mostly absorbed?

Root hairs

Where on the root is nitrate absorbed?

All along the root

Where on the root is Ca mainly absorbed?

Meristematic zone

Where is K absorbed in corn roots?

Elongation zone only

Where is NH4+ absorbed in corn and rice roots?

Root tip (apex)