Plant Form and Function III

Toxic Soils

"nothing can be more abrupt than the change often due to diversity of soil, a sharp line dividing a pine" - Alfred Russel Wallace 1858 Soils can be inadequate for plants in 2 ways: 1. not enough nutrients 2. toxins

Grasslands

(no fires in deserts because not enough leaf litter or vegetation) Fires before humans were mostly started by lightning storms with no rain -originally covered ~25% of earth's surface (now only 4% is protected) -recognized as the *most endangered ecosystem* on the planet #1 Threat: agriculture #2 Threat: not protected Grasslands = the *starting point for human civilization* -> agriculture and livestock ~Grasslands have always had a connected relationship with humans 1. Savannah Hypothesis: bipedalism originated in the Savannah (stood up to see above the grasses) 2. Fertile Crescent: birth of agriculture b/c flat and fertile soils (end of nomadic life) 3. Great Plains of North America

Zonation of the Rocky Intertidal

** physical and biological factors create regular patterns in the ecology of the rocky littoral zone -> plants are based on tolerance to the 3 extremes 1. *Splash Zone*: above the highest tide -gets moist -algae resistant to desiccation Indicator: *Ulva* = "sea lettuce" (can completely dry out) 2. *Supralittoral Fringe*: covered by only highest tide -"the black zone" b/c the indicator, *cyanobacteria*, dries out and looks black 3. *Midlittoral Zone*: covered/uncovered twice a day -not as resistant to drying but more resistant to wave action Indicator: *sea palm* (and red algae) 4. *Infralittoral Fringe*: wave break at lowest tide 5. *Infralittoral Zone*: only exposed by lowest tide at full moon Indicator: *brown algae*

ARTICLE: Effect of Nurse Plants on Microhabitat and Growth of Cacti (by Franco and Nobel 1989)

*Carnegiea gigantea* = saguaro cactus -> these seedlings grow under nurse plants *Nurse Plants* (H. rigida): plant that creates an environment that is less severe, allowing seedlings to grow underneath it -> create *microhabitats* that differ in character from their surroundings, providing shelter from harsh environments MICROENVIRONMENTS: characterized by PAR, soil surface temp., and soil N content *The Micro-Kjeldahl Method*: methods for quantitative determination of organic Nitrogen in a chemical substance *PAR* (Photosynthetically Active Radiation): the amount of light available for photosynthesis *Soil Water Potential*: the tendency of soil water to move *EPI* (Environmental Productivity Index): determines the productivity of a plant due to several variables (water uptake, temp, PAR, seedling location) and compare it when all variables are not limited CONCLUDING PARAGRAPH: "In conclusion, nurse plants *facilitate seedling establishment* by reducing *maximum soil surface temperatures*. However, competition for water and shading by the nurse plant greatly reduce the growth of the associated seedling compared with an exposed seedling. The magnitude of the reduction can by predicted by combining field measurements and models. The nurse plant also *provides a microhabitat with higher soil nitrogen levels, which partially offsets the reduced seedling growth caused by shading and competition for soil water*."

ARTICLE: Plant Development Under Snow (Kimball and Salisbury 1974)

*Corm* = a rounded underground storage organ consisting of a swollen stem base covered with scale leaves OBJECTIVE: 1. observe growth and development of 5 montane species under snow cover at temperatures near 0 °C 2. observe the degree of cell differentiation that occurs in plants growing at near-freezing temperatures INDEPENDENT VARIABLES: snow depth and temperature DEPENDENT VARIABLES: plant growth and development, cellular development, maturity of flowering parts CONTROLS: plant species, location, method of staining, time collected RESULTS: under great snow depths the mesophyll cells divided and the vascular tissue differentiated BUT stomate formation and intercellular air spaces were not found CONCLUSION: -certain plant species can grow and differentiate at near freezing temps -Cell division, differentiation, and organ formation can proceed at 0 °C -Photosynthetic mechanisms may develop under shallow snow layers and may become functional before complete snow melt LIMITATIONS: -no control study -lack of quantitative results -varying environmental conditions because field study SIGNIFICANCE: -no control study -fluctuating conditions because field study -methods section lacking detail

Phytoplankton

*Diatoms*: cell wall made of glass -they fix ~20% of all carbon on earth -either Benthic (living on the sea floor) or Planktonic (floating in the open sea) *Dinoflagellates*: they "whirl" -many produce neurotoxins -1/2 are photosynthetic -1/2 are more like animals

Sprouters (4 Types)

*Epicormic Buds*: along the stem, protected by cork -insulated and released from dormancy by heat of fire (**fire degrades the cork) ex. Eucalyptus, Grass tree, Tea Tree *Basal Shoots*: buds at the tree base -plants form these basal shoots when the upper part is killed by fire -re-sprout after fire *Lignotubers*: woody, underground stem with food and water reserves (adapted to fire and drought) ->enable rapid growth after fire *Geophytes*: underground bulbs = storage organs -die down to the storage organs

Necessary Adaptations for Survival in 3 Coastal Divisions

*Estuary/Coastal Fringe*: -excellent osmoregulatory capability -wide salt and temperature tolerance *Intertidal* (close to the land fringe): -amazing ability to withstand extremely harsh conditions *Submersed*: -adaptations to low light and an array of carbon concentrating mechanisms (DO, CO2 diffuse 10,000x slower through water than through air)

Alpine Zones (Top to Bottom)

*Fells/Screes*: not many plants but *cushion* plants *Alpine Meadow*: plants adapted to *bloom* under snow *Heath Zone*: a lot of plants from the *Ericaceae* family (heath plants) - also many acidic bogs

Adaptations to Short Growing Season

*Heliotropism*: motion of plant parts in response to sunlight (also warms the surface of flowers which increases the number of pollinator visits) ex. arctic poppy -Darwin: "the power of movement in plants" ->the *pulvinus*: joint-like section at the base of the leaf stalk; location for swelling of the petiole at the base of the leaf (potassium-ion pumps cause water movement to change the turgid pressure in cells) *Phototropism* = response to any light Tundra *"fast plants*" are like desert ephemerals: *fast life cycles*

Adaptations to Handle the Extremes

*THE EVADERS* (C3 plants) -Deciduous -Resurrection -Geophytes -Ephemerals *THE TOLERATORS* (CAM plants) -Succulents/Cacti -Ephedra and Creosote Bush (not succulents) -CAM Plants

Kelp Adaptations

*To Grazer Resistance*: production of unpalatable or toxic secondary metabolites *Maintenance of Photosynthesis at Low Light*: 1. possess accessory pigments and ability to alter pigmentation ->algae still have chlorophyll a (still at the center of photosystems) ->red algae have *phycoerythrin* (yellow-green; only found in algae) ->brown algae have *Fucoxanthin* (blue-green) --->both *pass* to chlorophyll a 2. *Pneumatocysts* = air bladders: gas filled floats keep fronds at the surface

Deciduous Evaders

*deciduous*~ loose leaves and flowers -in the desert they loose their leaves before a period of drought ex. Palo verde (legume) ex. Ocotillo (heath order)

General Desert Characteristics

-*Temperature Extremes* (45 - 0 °C in one day) -very little rain (*<12cm*) -*dew* is another source of moisture -*Erosional Winds/Rains*: ->most deserts are rocky, not sandy ->*no true soils* ->no leaf litter -*Indicators* (mostly found only and abundantly in that biome): yucca, cacti, asters, buttercups, creosote bush

Prescribed Burns

-*conservation* tool -reduces build up of *plant litter* -restores *historic influence* of fire on local ecology -helps control *invasive plants* -enables some species to *propagate* -creates/maintains *wildlife* habitat -manages *interface*: wild-land and urban fringe

General Characteristics of Rocky Intertidal

-*highly variable* temps, salinity, and degrees of exposure -high energy *waves* -grazers affect *species dominance* ex. crabs remove early colonizing algae (green Ulva) allowing colonization of late succession alga (reds) resistant to crab grazing -Indicator species (*protists* and *prokaryotes*) ex. *cyanobacteria* and *macro-algae*

Serpentine Plant Communities

-*unproductive* -*strong contrast* with surrounding vegetation -Numerous endemic, rare, endangered species ex. Pygmy daisy, Thorn mint -Serpentine plants (like halophytes) do *better* in standard soil -> they can *stand* serpentine soil

Rocky Intertidal and Kelp Forests (Part I of Ocean Biome)

-> all algae (no vascular or higher plants); just photosynthetic organisms Rocky Intertidal = the *harshest* habitat = the space between the lowest tide and the highest tide ->found in the North Resources: plenty of light, oxygen, and nutrients Challenges: -no soil -> *rocky substrate* -*wave action* ~Extremes in environment: *exposure, temperature, salinity* **baked to a crisp ~90°C -> immersed in fresh rain water -> inundated again in sea water

Kelp Forests

-> reside in the *subtidal*: a gentler, more environmentally dependable habitat than the intertidal **critically important ecosystems Kelp Forests grow up to 180ft tall = large brown algae Challenges: -less light penetration -a lot of grazers

Distinguishing Characteristics of Arctic Tundra

-COLD: (-34 to 12°C) -*little rain* (15cm-frozen most of the time) -> just a little more than the desert -*Permafrost* (prevents trees): permanently frozen layer of soil under top soil; limits plant growth -> top soil thaws during the growing season (only 6-10 weeks) -2 months of complete darkness -*no trees* Indicators: mosses, lichens (algae + fungi), grasses, dwarf shrubs, *cushion plants*

Serpentine Soil Challenges

-Low Ca:Mg ratio: -usually 1Ca : 7Mg -1Ca : 70Mg in serpentine soils -Low concentrations of N, P, K (essential nutrients) -normal = 5N : 7P : 4K -High Concentrations of Heavy Metals

Important Area of Plant Research

-Solanum cheesmaniae grows on sea cliffs in the Galapagos -> it is a halophyte related to tomatoes that has been bred with tomatoes so they can grow in salty soils -another project inserted a gene from bacteria into tobacco plants so that they would have a higher tolerance to metallic soils

Alpine Challenges

-UV -freezing temps and soils -bad soils -steep mountain side -short growing season

Possible Benefits of Hyperaccumulation

-anti-herbivory -pathogen resistance -allelopathy: affects another organism's reproduction, growth, survival -hyperaccumulation of Ni in laticifers (part of phloem) -> creates a green ooze in the plant -> has a repellent effect on D. melanogaster -> anti-herbivory

Kelp Forest Characteristics

-extend to depths of ~40m (low light levels) -> *blue-green light* penetrates best/deeply ->pigments for absorbing blue-green light = advantage -high energy waves near the top -grazers affect species dominance Indicators: brown algae (Phaeophyceae)

Other Features of Brown Algae

-holdfast, stipe, and blades c.s. of stipe: true tissues and primitive phloem (have sieve cells) ->Organization: -*Medulla*: center- loose, flexible -*Cortex*: with parenchyma tissue -*Meristoderm*: outside layer with pigments

Deserts

-located along the tropics of cancer and capricorn -Not all of them are hot (*tundra* = cold desert) - = *~30% land* on earth -covers half the African continent -Sahara = roughly size of the U.S. -3 Deserts in U.S.: 1. *Mojave* (S.E. California) 2. *Sonoran* (S.W. United States + N.W. Mexico) 3. *Chihuahuan* (S.W. United States + N. Mexico) - largest in N. America **Saguaro Cacti in the Sonoran Desert can store 5 tons of water (they expand)

General Characteristics of Tropical Grasslands

-moderate to hot temperatures (10 to 35°C) -seasonally dry (50-250 cm) -fire adapted *Trees* are often present (spread out) -> Africa: acacia trees -> Australia: eucalyptus trees (have a resin that spreads fire) -> Madagascar: SEASONAL DROUGHT SAVANNAHS -Indicator Species: Baobab trees: swollen stem with water (250,000 gallons) -"Subtropical Savannah Parkland" - 5 to 7 months of drought

Sea Palm Adaptation to Extreme Mechanical Stress

-only species of algae known to stand erect -fronds growing from the top of the stipe allow water to flow through -very flexible, can extend its length -bottom = the *holdfast* - function is to ground (no absorption function) -> grows into the rocks and excretes a gel-like substance: *alginic acid*

Plant Productivity Table

-open ocean plant productivity ~ desert -continental shelf ~ fresh water -*Estuaries + Marshes = highest plant productivity* (slightly greater than the rainforest) b/c light and nutrients

Adaptations to Near Freezing Temps and Frozen Soils

-plants are short with shallow root systems = dwarfed trees and shrubs -slow growing, low to the ground plants do best ex. lichens ex. Willow trees (genus Salix) -> arctic willow tree (same genus) is max 2 inches tall

Seeders

-produce seeds that are *dormant until fire* Fire is necessary for seed germination -> fire will degrade an inhibitor -flowering is initiated by fire Conifers (not grassland): pine cones are closed with a resin that degrades in fire, releasing seeds

Tropics

-salt accumulation in bark or old leaves -*pneumatophores* = "breathing roots that grow up; covered in lenticels that bring up air into spongy tissues -mangroves can be excluders or accumulators -*lenticels* = openings in woody tissue of stems for gas exchange -> modified to open at low tide, close at high tide to prevent water from entering air chambers -*vivipary*: seeds germinate while still attached to the parent plant (otherwise they would drop into anoxic environment) -> when they do drop, the radical is already capable of tolerating salt

Salty Soil Challenges

-salt is *toxic* at high concentrations -water is lost from the roots b/c water *moves to* the higher salt concentration in the soil -Halophyte review: enzymes-> exclusion or compartmentalization More Halophytes: -Ice Plants -Glass Plants (glasswort) -Exclusion: a sodium-potassium pump in root cells pumps excess sodium out (energetically expensive) -Absorption: salt is absorbed to increase salt concentration in root cells *so water moves in* -> both salt and water move up to the *leaves* -> salt *crystals* form as salt is excreted from leaves

Environmental Characteristics of Salt Marshes and Estuaries

-shallow (<30m) -*tidal inlet*: influenced by land and ocean, including tides -> *semidiurnal*: 2 high tides and 2 low tides each day ->high tide = saltier; low tide = more fresh --> a lot of osmoregulation -highly productive TEMPERATE INDICATORS: -cordgrass (emergent, brackish) -seagrass (submersed, marine) TROPICAL INDICATORS: -Mangroves: 16 families; convergent evolution (evolved independently in 16 different families) -Mangrove distribution = similar latitude to tropical rainforests

Distinguishing Alpine Characteristics

-temperature drops *6.5°C* per 1000 meter (3000 ft) -*tree line* = where the summer max = 10°C (50°F) -intense *UV radiation* -intense *winds* -*thin, infertile soils*

The Atacama

-the driest place on earth (in Chile) -gone almost *50 years* without rain -gets fog/dew MOUNTAINS: -have a *windward side* where most of the clouds form and rain falls -the other side is the *leeward side* -> where deserts often form

Adaptations to Salt Tolerance

-the enzyme activity in both a salt tolerant and salt intolerant plant goes down with increased salt (*the enzymes of halophytes are not intrinsically salt tolerant*) -> salt tolerant plants (halophytes) can *protect the enzymes* from salt in 2 ways: 1. *Excluding*: keep salt out of roots -deposit apoplastic barriers in the roots to restrict salt movement up into the shoots -deposit waxy substance *suberin* in the *endo- and exodermis* = 2 layers of suberin -increased salt -> increased expression of suberin genes 2. *Accumulating*: compartmentalize salt in vacuoles and excretion of concentrated salt solution through glands and bladders -shift salt mesophyll to outside leaf -salt crystals often form on surface of halophytes -*salt bladders* = modified trichomes (more than 50% of salt entering leaves can then be excreted through these bladders

General Characteristics of Temperate Grasslands

1. *Prairie*: interior lowland grasslands 2. *Steppe*: montane or high elevation grasslands -Hot summers, cold winters (range -10 to 30°C) -*seasonally dry* ~50cm (dryer in summers) -Fire Adapted -Rich, fertile soils -> in tropical rainforests the nutrients are taken up in plant biomass -> in grasslands, fire regularly recycles the nutrients back to the soil ~"Naturalness" is difficult to determine b/c constantly disturbed by humans -> regular disturbance ensures that is stays a grassland

Marine Flowering Plant Group

1. *Sea "Grasses"*: (not true grasses) -form meadows -important food group for manitous etc. -*green* and grow entirely under water -> need clean, clear water (no alternative pigments) 2. *Cordgrass*: (true grass, part of Poaceae) -emergent

2 Types of Adaptive Species

1. *Sprouters*: have buds that are dormant and protected during fire then sprout after a fire 2. *Seeders*: produce seeds that are dormant until fire

4 Water Sources

1. Seasonal Rains 2. Desert Oasis 3. Dew 4. Wash

ARTICLE: Defenses Against Grazing in the Rocky Intertidal (Pelletreau and Muller-Parker 2002)

3 Possible Reasons for Sulfuric Acid in Kelp: 1. *Allelochemicals*: prevent growth of other plant competitors 2. *Antifouling*: preventing micro-algal growth on surface of kelp 3. *Anti-herbivory* Questions: 1. What is the green urchin's food preference? 2. Is preference related to polyphenols, acid, nutrition? 3. At what pH is acid an effective deterrent to urchin grazing? SITE: subtidal zone, 5 phaeophyte algae, 60 urchins for each of the 2 experiments EXP. 1: Multiple Choice Feeding Preference Experiment INDEPENDENT: type of algae, starved or not starved DEPENDENT: dry weight of algal pieces CONTROL: algae but no urchins CONTROLS: container type, # of urchins per arena, shape of algae was varied, distal algal samples, environmental conditions REPLICATES: 10 starved, 10 fed EXP. 2: Sulfuric Acid Feeding Preference Experiment INDEPENDENT: pH value of food DEPENDENT: percentage of food consumed CONTROL: food with distilled water added (~6.2 pH) CONTROLS: food mixture, weight, and size; environmental conditions, length of experiment REPLICATES: 14-17 starved urchins for each of 11 pH treatments CONCLUSIONS: -sulfuric acid deters sea urchin herbivory (both fed and starved) -food becomes significantly less desirable at pH 3.5 and below -high polyphenol concentrations in A. marginata may have also deterred herbivory - no definitive conclusion on polyphenols -field observations support lab results -N content was not correlated with food choice LIMITATIONS: there may have been another algal factor at play that was not tested for -polyphenols were not tested independently FUTURE: in tropical regions, where N limitations may be a strong selective factor, the results of the same experiment may vary -also *how* sulfuric acid affects the digestion rate and absorption of algal material in sea urchins -independently test effect of polyphenols

Dew

= *condensation of fog that is brought in from cool sea breezes* ex. happens in the Atacama

Taiga

= Northern Coniferous Forest - (30 to 35°C) (up to 95°F) - short growing season (water frozen most of the time) -permanent snow cover in winter -*acidic soils* -*reduced evaporation* -> ponds and wetlands -*low biodiversity* but *evergreen* Indicator Species: the wolverine

Wash

= a usually dry river bed, but sometimes *rain from the top of the mountain* flows down it -> a flash flood *once or twice a year* ex. Mojave desert (plants tend to seek the places with water availability: washes and rock fissures)

Evolution

= the change in heritable trait densities in a population as successive generations replace each other -*Natural selection* places a selective pressure on heritable traits that improve the *relative fitness* of individuals in a population. This pressure can lead to a change in heritable trait densities in the population as successive generations replace each other = evolution *Divergent Evolution*: accumulation of differences between groups (can lead to speciation) -The arctic willow tree is from the same genus, Salix, as the willow trees found in N. America though they are phenotypically very different (artic willow only grows 2 inches tall) *Convergent Evolution*: polyphyletic organisms independently evolve similar traits as a result of adapting to similar environmental conditions -mangroves: evolved independently in 16 different plant families -cushion plants: many different genera (both sunflower and carrot families) evolved similar anatomical structures (like no apical dominance and florets) *Co-evolution*: the influence of closely associated species on each other's evolution ->closely associated species can influence each other's evolution ex.

Shallow Seas

=Estuaries (brackish water/marshes), Intertidal, Continental Shelf *Estuaries*: large flowing rivers into the sea - salinity is between fresh and salt water (0 in fresh, 35 in sea) -extremely important nursery grounds -*"biological filters*" for watershed and airshed pollution - *major oxygen source, carbon sink* *Continental Shelves*: extend 50 miles, ~500ft deep (light goes down ~200ft in clean, clear water) -petroleum, commercial sand and gravel, fishery resources **wave action distinguished intertidal from estuaries and shelf -only *7%* of oceans is coastal area - >90% of production of fish, shellfish, and seaweeds -remarkable biological *productivity* -diverse array of habitats -by far the most important area both ecologically and economically -71% of earths surface = oceans -extremely vulnerable to human activities; centers of human activity for millenia

4 Main Adaptations for Exposure/Dessication Resistance:

ANATOMY 1. *Large Size*: lower SA:volume ratio -> less SA = less evaporation 2. *Crustose Form*: resurrection ability BIOCHEMICAL (modified cell wall components and structure) 3. *Mucilage*: thick mucous that holds on to water 4. *Alginic Acid in Primary Cell Wall*: a polysaccharide known to hold 200-300x its weight in water (used as a gelling agent in human products) - thick & sticky

Cool Desert Plant Applications

Blue Agave: tequila Ephedra: contains natural form of ephedrine (weight loss) Peyote: source of mescaline; 3000yr history of medicinal use by natives

ARTICLE: Smoke-induced flowering in the fire-lily Cyrtanthus ventricosus (Keeley 1993)

Cyrtanthus ventricosus (a geophyte) flowers ~9 days after a fire event and lasts for 5-6 days OBJECTIVE: to determine what aspect of fire stimulates flowering (is it the direct or indirect effects of fire?) HYPOTHESIS: smoke and ethylene are the cues that induce C. ventricosus to switch from dormancy to flowering (though they never test them together) *ethylene*: colorless gas that can be a component of smoke INDEPENDENT: exposure to smoke or ethylene (leaves intact or not) DEPENDENT: emergence of flowers CONTROL: no smoke or ethylene CONTROLLED FACTORS: maintenance, light, water, chamber temp, chamber size, ethylene concentration REPLICATES: 2 per experiment RESULTS: flowered only with smoke -> ethylene is not the active component of smoke LIMITATIONS: they burned pine..why? -few replicates -only tested one possible component of smoke FUTURE DIRECTIONS: -analyze the smoke from burning the natural surrounding vegetation -> run many more replicates of this experiment with different components of this smoke

Ephemeral Evaders

Ephemerals are *annual* plants that die back down to a *seed* with seed coats covered in *germination inhibitors* ~~reside as a seed during droughts -> the germination inhibitors get *washed away* in a good rain -> germination = *fast* life cycle plants -> very beautiful flowers Ex. *Desierto Florido* = Atacama desert after a rain -> Article (Vidiella et al. 1999): -whole thing over in 19 weeks -dominated by geophytes and annuals (ephemerals) -peak flowering occurred two months after rain

Plant Nutrition

FROM SOIL: 1. *[Fe, Cu, Mo, Zn]* <1% dry weight = micronutrients: essential at small quantities but toxic at high quantities; exclusively inorganic 2. *[Mn, Na, Cl, B]* 1&2 Various Other Functions: osmotic potentials, membrane permeability, conductance, enzyme activation 3. *[S, Ca, Mg, Si]* S: 2 amino acids Ca: enzyme activation Mg: center of chlorphyll a molecule -> low Mg leads to chlorosis Si: structural function = cell wall deposition (lower energy cost than lignin) 4. *[N, P, K]* N: amino acids, nucleotides P: nucleotides, lipids, nucleic acids, P-sugar backbone of DNA K: enzyme activation, Na-K pump -> important for opening and closing of stomata to change turgidity FROM AIR: *[C, O]* >90% of dry weight FROM WATER: *[H]*

Geophytes Evaders

Geophytes ~ dry down to their *underground storage organs* (bulbs) ex. poppies and other buttercups

Adaptations to Intense UV Radiation and Wind

LIGHT -*leaf hairs* reflect light and epidermal *pigments* (i.e. flavonoids and carotenoids) absorb harmful UV-B radiation (flavis = yellow) WIND - *cushion plants* are ultimate alpine and arctic survivors -> Anatomy: *no apical dominance* (no dominant central stem/branch) -at the tip of each branch the leaves create *florets* -> all together these create a *microenvironment* that is warmer with more moisture -> also creates enough leaf litter for decomposition into *nutrients/soil* Cushion Plants = example of *convergent evolution* of many *different genera* (from both the sunflower and carrot family)

Plant Adaptations to Serpentine Soils

LOW NUTRIENT LEVELS: -*greater* absorption of *Ca*; *reduced* absorption of *Mg* -> soil = 1Ca:70Mg ; internal ratio (inside plant) = 1Ca:7Mg -> mechanism unknown HIGHER Mg REQUIREMENTS: -serpentine grass requires high concentrations of Mg for growth ABILITY TO ACCUMULATE METALS: *Hyperaccumulators*: some species hyperaccumulate Ni, Cu,Cr, or Nn -> (used for *phytoremediation*) -they either: 1. *Compartmentalize* the metals 2. *Chelation*: formation of bond between metal and ligand -> marking it for compartmentalization ->*phytochelators*: in plants, a type of bonding between ligands and metals **phytoremediation: use of living green plants to clean up contaminants in a growth media

Challenge Examples

Lower Intertidal Red Algae: can get bleached and die from high UV light when exposed at low tide Mass destruction from Storms -->but many still survive -> *perennial crustose stages* of algae are "master competitors" for space while also avoiding predators (grow ~5 cm) in 80 years In the Arctic, brown seaweeds are frozen for 6 months out of the year and will resume photosynthesis 4 hours after thawing -> get *agar* from seaweeds

Seasonal Rains

Mojave rains = winter (~13in) Sonoran rains = winter and summer (~6in) Chihuahuan rains = summer (with agave)

Franco & Nobel

OBJECTIVE: to determine the affect of nurse plants on C. gigantea and F. acanthodes seedlings HOW: characterized each species with and without canopy (exposed/not exposed) to see how it grew, measuring: temp., PAR, water uptake, EPI, soil nitrogen, root distribution, seedling growth RESULTS: *all* C. gigantea seedlings found under *center* of a nurse plant compared to *most* F. acanthodes found under nurse plant and *scattered* under -*higher N* under nurse plants -*less temp. variation* under nurse plants -*daily PAR reduced* under nurse plants (higher PAR south of center) -*less water uptake* and *lower EPI* under nurse plant -water uptake increased when more exposed, on south side, or increased rain fall -EPI increased for exposed seedlings and those on the south side CONCLUSIONS: under nurse plants surface temp stays lower, EPI is lower due to water competition and shade -growth reduction is slightly offset by higher N levels (predicated 64% reduction, actual 32% reduction) -growth reduction decreases as seedling grows -seedlings respond to smaller amounts of rainfall than nurse plants -nursing a plant can sometimes increase water uptake in nurse plants ~Nurse plants provide a more stable microhabitat ~Microhabitats do have some limiting factors in regards to PAR ~PAR limiters offset by soil rich in nitrogen ~Magnitude of reduction can be predicted by combining field measurements and models LIMITATIONS: field study, can't control other factors impacting seedling growth (like other soil nutrients that were unaccounted for) SIGNIFICANCE: -future determinations of exact N impact

ARTICLE: Root Metabolism in the Black Mangrove (McKee and Mendelssohn 1987)

OBJECTIVES: -to understand the metabolic adaptations of plants in flooded, highly reduced soils -To determine the effect of hypoxia on A. germinans, specifically: ->the activities of several enzymes and metabolites in anaerobic root metabolism ->adenine nucleotide concentrations and energy status in the roots EXP. 1: *Measurement of Root Gas Concentrations* ->O2 and CO2 sig. decreased after 1 hr N; N increased EXP. 2: *Measurement of Enzymatic Activity* ->under hypoxic conditions: ADH increased 3x, MDH, LDH sig. increased, PEPc no sig., ME sig. decreased EXP. 3: *Measurements of Metabolite Concentrations* (by measuring NAD+ reduction) ->hypoxic: sig. increase in malate, smaller but still sig. increase in alanine; ethanol appeared unchanged but possibly because of diffusion out of roots EXP. 4: *Measurements of Adenine Nucleotides* ->hypoxic: ATP and ADP sig. decreased ->energy avail. from ATP decreased as seen by sig. decrease in TAN and AEC INDEPENDENT VARIABLE: were always air/nitrogen treatment except in Exp. 1: also 1hr/96hr treatments CONTROLS: always gas flow rate, nutrient solution, seedling growth conditions (and treatment time except in exp. 1) CONCLUSIONS: -the roots respond metabolically to hypoxia by *alcoholic fermentation* -O2 sig. decreased despite presence of aerenchyma tissue -low levels of ethanol, lactate, and alanine (*products of alc. fermentation*) are possibly attributed to diffusion -the *energy status* of hypoxic roots was considerably lower than in aerated roots -glycolysis and alc. fermentation may be contributing to the maintenance of ATP levels -*metabolic adaptations* may contribute to *tolerance* of flooded soils as much as *internal oxygen diffusion* does FUTURE: to understand why alanine accumulates in hypoxic roots LIMITATION: the use of seedlings -> the results, specifically O2 concentrations, may be different if this experiment were done with more mature mangroves (with more developed pneumatophores)

Resources and Challenges

RESOURCES: -nutrients + light CHALLENGES: -periods of inundation (floods) and desiccation -changing salinity -low oxygen (both in water and sediments) -sometimes low light -reproduction (getting pollen to stigma)

Adaptations to a "salt" watery existence (similar to fresh water existence)

Reproductive Adaptations (Vegetative): -rhizomes, seed dispersal by water -asexual Non-vegetative Reproductive Adaptations: -ex. *hydrophyllous* (rare): pollen released under water -> only seagrasses do everything under water (male and female flower parts) Adaptations to Low Light (only in deep water) -mostly seen in the algae 1. *accessory pigments*: ex. red tide = a dinoflagellate bloom 2. *mixotrophy*: switch from photosynthesis to heterotrophy (eat through phagotrophy) More Adaptations to Oxygen: -thin cuticle, thin epidermal layer for gas exchange -long, narrow leaves to maximize gas exchange (more surface area) -Vestigial Structures: left over, no longer used ex. stomata in sea grasses Adaptation to flowing water: -sclerenchyma fibers provide flexible strength

Resurrection Evaders

Resurrection plants *dry up* in a period of drought then quickly thrive in the presence of water ex. Selaginella lepidophylla ex. Lichens (crustose lichens are incorporated into the rock surface and grow very slowly)

Arctic and Alpine Regions

WINDWARD SIDE of a mountain: *Alpine* is above the tree line (wind -> evaporation -> condensation -> rain) 1. Fells/screes 2. Alpine Meadows 3. Heath Zone *Taiga* is below the tree line Fireweed: one of the first plants to colonize burned sites -> native americans use it to treat burns Alpine = mountain-side tundra Tundra from Finnish word "tunturi" = treeless plain Arctic Tundra: -> too cold for trees; dry areas in the arctic (Alaska) -> 70° N latitude or near equator high on mountains

Aquatic Biomes

plants here = primary producers or phototrophs with oxygenic photosynthesis and the "universal plant pigment" chlorophyll a -99% of vascular plants are on land -only 0.02% flowering plants made it back to marine

Adaptation Significance

~ "adaptation is the signature of evolution by natural selection" -"adaptation to novel environments results in origin of new species"

Desert Biome

~"Desertum" = Abandoned Place -> not just hyper-arid, sandy deserts *True Deserts*: receive ~*4*in rain or less per year *Semi Deserts*: receive ~*15*in rain or less per year ->to survive in the desert a plant has to be *fast or tough* -california poppies = fast -Joshua Tree (a yucca plant) = tough (only found in western U.S.)

Poaceae = true grasses

~*4th Largest* Plant Group (after asteraceae, orchids, and legumes) ~100,000 species known -found from the arctic to the antarctic (= 1 of 2 plants in Antarctica: *Deschampsia antarctica*) -grow at the *base* (not tips): Monocots ->intercalary meristems -> animal grazing and fire take the top but they keep growing -*fire adapted* -wheat, corn, and rice >50% of consumed calories worldwide COOL SEASON Grasses: C3 photosynthesis ->Annuals: wheat ->Perennial: fescue - on the quad WARM SEASON grasses: C4 photosynthesis ->Annuals: corn ->Perennials: indiangrass

Evergreen Adaptations

~*Needles*: cope with low water -> filled with *resin* (distasteful) -> thick waxy cuticle -Stomata are *sunken* way down -*Extracellular Freezing*: cells pump all the water into the apoplastic space so that freezing doesn't damage organelles inside the cell -Tree *Shape*: triangular - allows snow to fall off -> *compacted* - reduces evapotranspiration Form and Function: low surface area doesn't accumulate snow -> continues photosynthesis

Tides

~caused by gravitational pull between sun, earth, and moon 2 Types of Tides: 1. *Spring Tide*: sun, earth, and moon all align -> *full moon* -big difference between high and low tide (=highest and lowest) 2. *Neap Tide*: sun, earth, and moon create a right angle -> small difference between high and low tide -> *quarter moon*

Serpentine Soils

~come from *ultramafic rock* = igneous rock (from cooling of lava) ->with *low* Si +K and *high* Mg + Fe ->green from the metals (soils are often red because of rust) -can be found abundantly in California -> make of 1% of California land but contain 10% of endemic California plant species (often deciduous and gymnosperms) -also found in New Caledonia Human Use of Ultramafics: Ni, Chrome, Asbestos, Cu, Talc, -plants indicate where to mine -economically valuable -gem stones: jade, peridot

Tolerance of Temperature and Salinity Variations

~food reserves such as mannitol, sucrose, and glycerol *lower freezing point* and function in *osmoregulation*

Algae

~most of the red and brown algae are in the ocean

Desert Oasis

~places where wind has blown away sand and/or rocks to expose *fossil water* (fell during an interglacial time) -> you find a lot of plants not normal for deserts (palms are common) Ex. Fan Palm Oasis in California

Adaptations for Hanging On

~seaweeds are anchored by holdfasts and often have a strap-like shape

Tide Pools

~separated from the ocean for varying periods depending on their location -> *salinity stress* *Evaporation* -> increased salinity -> salt can be caked around edges for days to weeks in high intertidal pools ->only certain organisms capable of *osmoregulation*: the active regulation of solutes in the cytoplasm (Na, K, Cl, sugar) ex. Ulva (green algae) ex. N-fixing cyanobacteria (blue-green alga)

Cross Section through a Saguaro Cactus

~the cactus stem is modified for water storage *interior woody tissue and pletes *organ pipes 1. Center = *pith* 2. Cylindrical network of *lignified rods* extend through the length of the stem like steel reinforced in concrete 3. *cortex* is modified with *ribs* that enable *expansion* after rain

The Tolerators

~~don't die back Adaptations to Reduce Water Loss: 1. *Shallow fibrous root systems*: widespread and shallow maximizes water absorption after a rain -no tap root 2. *Leaves* are often *small/narrow* and covered with a thick *waxy cuticle*, *hairs*, and *sunken stomata* Cacti and Succulents: -*spines* are modified leaves ex. saguaro cacti and prickly pear -succulents are the ones using *CAM photosynthesis* Not Succulents/Cacti: ex. *Ephedra*: a conifer, very thin leaves ex. *Creosote Bush*: smells like gun powder - tea used as a decongestant and anti-spasmodic - prevention of HIV transcription

Tolerance of Erosion and High Soil Temperatures

~~few plants -> increased evaporation -> dry -> erosion -morphologically similar to desert plants; narrow leaves, small stature, highly developed root systems Recent Genetic Analyses: ->identified serpentine-adaptive quantitative trait loci (QTL) ->useful for creating new agricultural strains -drought tolerance genes are as important as metal tolerance -serpentine adaptation has *evolved independently* multiple times within the *same species*