1. Mineral Nutrition in Plants I
When one tugs at a single thing in nature, (s)he finds it attached to the rest of the world.
John Muir

2. Assimilation
Every organism is an open system connected to its environment by a continuous exchange of energy and nutrients....
…in the energy flow and chemical cycling that keep an ecosystem alive, plants…perform the key step of transforming inorganic compounds into organic ones.
…and to synthesize organic matter, plants also requires raw materials in the form of CO2 H2O and a variety of mineral present as inorganic ions in the soil.
…prelude to Chapter 37, Cambell and Reece.

3. Sessile and Dainty …stationary,
…growth and development are a plant’s version of locomotion,
primary and lateral roots exploit new space,
axillary buds grow new stems, yielding new leaves, that in turn build mesophyll cells, etc.
Dainty?
- generally, no excretory organs.

4. Where does it go? vacuole Exclusion; Sequestration;
selective permeability of the plasma membrane (keep out),
active transport of unwanted substances (kick out),
secreted plant products take unwanted substances out of solution,
vacuole
Sequestration;
most metabolic waste products and toxic substances are transported to the vacuole, some to other compartments (i.e. ER),
Programmed Cell Death
Apoptosis and Abscission (+);
programmed cell death and programmed organ death, (i.e. leaf drop).

5. Plant Nutrition and Mineral Transport
What elements are found in plants?
How and where do they function?
Phytoremediation?
Nutrient Deficiencies?

6. Relative Elemental Analysis of Plants
H2O or CO2
Soil

7. Essential Nutrients Essential mineral nutrients:
one whose absence prevents a plant from completing its life cycle (classic definition),
or, one that has a clear physiological role (current modification of classic definition).
Macronutrient: required in relatively large amounts,
Micronutrient: required in relatively small amounts.

8. Group 1. Nutrients that are part of carbon compounds.
Use for reference, but we’ll organize the nutrients according to biochemical function.
Group 1. Nutrients that are part of carbon compounds.
Group 2. Nutrients that are important in energy storage or structural integrity.
Group 3. Nutrients that remain in ionic form.
Group 4. Nutrients that are involved in redox reactions.

9. Structural Elements, Covalently Bonded I Group 1: Nutrients that are parts of carbon compounds...
N: amino acids, proteins, nucleic acids, co-enzymes, etc.
S: cysteine, methionine and proteins; lipoic acid and coenzyme A, etc.
low S
high S
Plants assimilate these nutrients via biochemical reactions involving oxidation and reduction.

10. Mesophyll Cell Root Cell Assimilation in leaves; cysteine. Storage
Transport in the xylem sap to leaves.
Some assimilation into cysteine in the root,
Root
Cell
Storage
Uptake;
Secondary Active Transport

11. Sulfur Compounds
…antioxidant.
…hormone.

12. Phytochelatins
Chelate: a complex in which a metal ion is bound by a ligand,
chelation: to remove (a heavy metal, such as lead or mercury) from solution by means of a chelate,
Traditional Heavy Metal Pollution Treatments
remove, and/or
encapsulate (with concrete or asphault),
Phytoremediation,
plants uptake, chelate and sequester metals,
harvest plants, dry, dispose (less mass).

13. Phytoremediation Accumulation in harvestable shoot tissue.
Phytodegredation
Metal ions or toxins
Phytoextraction
Phytostabalization

14. Structural Elements, Covalently Bonded II Group 2: Nutrients that important for energy storage or structure...
Equisetum hyemale
Si obligate
P: sugar phosphates, nucleic acids, proteins, phospholipids, ATP,
Si: deposited as amorphous silica in cell walls, contributes to cell wall mechanical properties,
“essential” for life cycle in only a few species in hydroponic experiments,
however, in the field, probably essential for survival of many more plants.
B: nucleic acid synthesis?, transport?, chlorophyll biosynthesis?,
and cell wall function.

15. Rhamnogalacturonan II
11 different sugar monomers,
> 21 enzymes required for synthesis.
Structure is conserved in the cell walls of all higher plants,
boron links two Rhamnogalacturonan II monomers,
contributes to cell wall function through cross-linking with cellulose microfibrils and other cell wall components.

16. Salts, Co-factors, and Redox Reagents Group 3,4: Nutrients that remain in ionic form...
Salts and Co-factors:
K, Ca, Mn, Zn, Na, Mg,
K: co-factor for > 40 enzymes, and is the principle cation for establishing cell turgor and control of membrane potential,
Ca: contributes to cell wall structure, membrane structure, and acts in signal transduction,
Mg: co-factor in enzymes required for phosphate transfers, and a component of chlorophyll.
Redox Reagents:
- Fe, Cu, Mo, Mn.

17. Dose Response Curves
saturation
toxicity
threshold

18. Nutrient Deficiencies
Difficult in Soils
Chronic and acute deficiencies of several nutrients may occur simultaneously,
Deficiencies (or excess) of one element may induce deficiencies (or excess of another element.,
Hydroponics
Pathogens often induce symptoms similar to nutrient deficiencies.
Mineral deficiencies are relatively easy to identify in controlled conditions.

19. Recognizing Deficiencies
Leaf Clues;
if an essential nutrient is relatively mobile, symptoms generally appear first in older leaves,
deficiencies in relatively immobile nutrients generally appear in young leaves.
Nutrients classified based on their tendency to re-translocate during deficiencies.

20. K+ Transport
1. K+ is transported across the root cell plasma membrane,
2. K+ is transported from the root symplast to the xylem,
3. K+ is transported via xylem sap to the older leaves,
diffuses to the apoplast and is transported into the mesophyll cells,
- or, K+ diffuses into, or out of the phloem.
5. Moves in source-sink direction.

21. Means for using excess carbohydrates.
Deficiency Characteristics Group 1: Nutrients that are parts of carbon compounds...
N (mobile) is most often the limiting nutrient in natural systems,
it is a critical components in many plant cell components (especially proteins) and deficiencies quickly limit growth,
the most typical deficiency characteristic is chlorosis (yellow leaves),
slowly developing deficiencies produce short, woody stemmed plants,
anthocyanin production (red pigment).
Means for using excess carbohydrates.
S (immobile) is generally available,
deficiencies (especially proteins) quickly limit growth,
similar general characteristics as seen in N deficiencies.

22. Deficiency Characteristics Group 2: Nutrients that important for energy storage or structure...
P (mobile) can be a limiting nutrient in natural systems (esp. at high pH),
it is a critical components in respiration and photosynthesis as well as a key component of the phospholipids that make up membranes,
the most typical deficiency characteristics are stunted growth and dark green leaves,
necrotic lesions may occur,
anthocyanin production (red pigment).
Si (mobile) is usually available,
lodging (falling over) and prone to fungal infections.
B (immobile) lots of deficiency characteristics, especially necrosis (cell death) in expanding cells.

23. pH and Nutrient Availability
The pH of the soil affects the availability of all elements,
Plants adapt to the soil pH,
directly modify soil pH,
adapt mechanisms to operate in extreme conditions.
Width of bar corresponds to relative availability

24. Deficiency Characteristics Group 3: Nutrients that remain in ionic form...
K (mobile) deficiencies,
mottled or marginal chlorosis, veins retain their color, necrosis at margins, thin stems, short internodes,
Ca (immobile) deficiencies,
Necrosis in areas of cell division and rapid expansion (meristems), leaf primordium, etc.
Mg (mobile) deficiencies,
chlorosis, beginning especially between veins,
old leaves, or youg leaves?

25. Deficiency Characteristics Group 4: Nutrients that are involved in redox reactions...
Fe (immobile) can undergo Fe2+ <--> Fe3+, are are important in electron transfer reactions,
chlorosis, especially between veins,
would you expect to see it in older or younger leaves first?
Zn (mobile) deficiencies,
dwarfism, extreme cases display chlorosis.
Cu (immobile) deficiencies,
dark green leaves, necrotic spots appearing at the tips of young leaves.

28. Wednesday Symbiosis, Rhizobium, Mycorrhizae,
Think about your questions. Ask questions.