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This lecture was given in March, 2013 as part of the California native plant gardening series ‘Out of the Wilds and Into Your Garden’
Citation preview
3/11/2013
1
© Project SOUND
Out of the Wilds and Into Your Garden
Gardening with California Native Plants in Western L.A. County Project SOUND – 2013 (our 9th year)
© Project SOUND
Warfare in the Garden how plants protect themselves
from pests and invasions
C.M. Vadheim and T. Drake
CSUDH & Madrona Marsh Preserve
Madrona Marsh Preserve
March 2 & 5, 2013
Why consider plant defenses?
Plants – and everything about them – are inherently interesting
Understanding how plants interact with other living things may improve your gardening
Plants and animals are more similar than we think – at least at the cellular level
May suggest novel medicines, pesticides and other useful prodcucts
© Project SOUND
Plants are primary producers
That means they are ‘food’ to many organisms © Project SOUND
http://www.glogster.com/beckeyy/food-web/g-6mp96eehhgdfvco22h8bna0 http://www.bostonbakesforbreastcancer.org/summer-sun-radiation-and-chemo/
Photosynthesis:
stored energy,
other (biomass)
3/11/2013
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But plants aren’t merely generous benefactors
or faithful servants….
© Project SOUND
http://thebillfold.com/2012/04/reader-mail-how-to-be-a-generous-person/
After all, plants have to live too…
Capturing energy needed for life (photosynthesis)
Obtaining water: roots
Obtaining nutrient chemicals (primarily through the roots)
Reproducing: seed or vegetative
Protecting themselves from anything that impacts the above:
Abiotic factors: temperature, weather, soils etc.
Biotic factors: living things
© Project SOUND
CA Goldenrod - Solidago californica
Plants are far more
complex than most
of us realize
They interact with many types of organisms – for better or worse
They are at least as complex as higher animals
They were not set on this planet for our use alone
They often behave more like plant warriors than like shrinking violets
© Project SOUND
http://img.ehowcdn.com/article-
new/ehow/images/a08/4f/it/avoid-leggy-seedling-
800x800.jpg
http://gorillaartfare.com/character-design/two-little-kittens/
Types of defenses
Physical barriers (preformed or induced) Waxy cuticle
Trichomes/leaf hairs
Tough epidermis
Sticky gums & resins
Prickles, barbs and thorns
Dense growth habit
Hard covering to protect seeds
Etc.
Defense chemicals Preformed: always ready
Induced: produced only when needed (usually when stimulated by an attack)
© Project SOUND
3/11/2013
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Phytochemicals: the basis of plant chemical warfare
Phytochemicals: non-nutritive plant metabolites that are essential for the survival and proper functioning of growth and reproduction in plants
Often involved in protection against herbivores, pests and micro-organisms (or other environmental stresses)
Sometimes used by animals that eat them: As defense chemicals
As human plant-based medicines, flavorings and other uses
© Project SOUND
http://naturallyjodi.blogspot.com/2012/08/medical-news-
2012.html#!/2012/08/medical-news-2012.html
Phytochemicals are sometimes
called secondary metabolites
Phytochemicals
© Project SOUND
The distribution of phytochemicals within plants is often tissue/organ specific
These molecules tend to be concentrated in outer cell layers of plant organs, suggesting that they may indeed act as deterrents to pathogens and pests.
These compounds are of two types:
Constitutive chemicals: made during normal growth and development (preformed antimicrobial compounds, or “phytoanticipins”)
Induced chemicals: absent from healthy plants, accumulating only in response to pathogen attack or stress (‘phytoalexins’)
Whether a given compound has a defensive function is the
subject of much current interest & research
http://plantpathology.uark.edu/4844.htm
Competition between plants: it’s a fact of life,
particularly in our mediterranean climate
Light
Water
Soil nutrients
Access to services of beneficial organisms
© Project SOUND
http://primarybestsc.blogspot.com/2012/10/plants-competition.html
Plants sometimes have to ‘fight
dirty’ to best their competitors:
allelopathy
http://the-gist.org/2012/09/allelopathy-when-plants-attack/
© Project SOUND
Southern CA Walnut – Juglans californica
http://biology.csusb.edu/PlantGuideFolder/JuglansCalif/JuglansCalifPage.htm
3/11/2013
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© Project SOUND
S. CA Walnut: not for
every yard
Proper location: consider
Size: moderate for tree Light: full sun/part shade Soils: clay soils best
Water regime:
Tolerates seasonal flooding No or very occasional deep water
in summer (hot gardens)
Allelopathy:
Leaves produce chemicals toxic to other plants
Can’t grow plants under walnuts
http://biology.csusb.edu/PlantGuideFolder/JuglansCalif/JuglansCalifPage.htm
http://www.phytoimages.siu.edu/imgs/paraman1/r/Juglandaceae_Juglans_
nigra_4178.html
Allelopathy: one type of chemical warfare
Term from allelon ("of each other“) and pathos ("to suffer“).
Refers to the chemical inhibition of one species by another.
Allelopathy has generally come to mean the deleterious effect that one plant has on another through the production of chemical retardants
The "inhibitory" chemical is released into the environment where it affects development and growth of neighboring plants.
Process is often more complex:
Allelopathic plants are also capable of stimulatory effects
The chemical producing plant may also inhibit itself with the same chemicals that inhibit its neighbors
The process may involve other organisms [soil microbes]
© Project SOUND
Plants release allelochemicals in several
different ways
Above ground
Leaves release volatiles
Leaching from leaves
Leaching from plant litter or on decomposition
Below ground
From above-ground leachates
Root exudates
Decomposing roots
© Project SOUND http://pubs.ext.vt.edu/430/430-021/430-021.html
Often responsible for colored barks, root barks and heartwoods
Example: Juglone (C.I. Natural Brown 7)
In leaves, roots, husks, and bark of plants in the Juglandaceae family
Is toxic or growth-stunting to many types of plants and insect herbivores - inhibits key enzymes needed for metabolic function.
Awareness of walnut toxicity dates back at least to Roman times
Used as: an herbicide
a dye for cloth and inks
a coloring agent for foods and cosmetics (hair dyes).
Folk medicine – ground/extract green hulls
© Project SOUND
Naphthoquinones
http://kremerpigments.com/shopus/index.php?cat=0104&lang=EN
G&product=37300&sidFEE4B14F27014E7795A5F1BD0DD62743=
63e5300d98a56f6479a23d579380ca6a
3/11/2013
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Juglone is an effective toxin because it affects
basic processes required for life
The active agent inhibiting growth of other plants was suggested by Massey in 1925; confirmed by Davis in 1928.
Juglone disrupts oxygen and food use in both plants and animals, a respiration poison. Juglone is like cyanide in its effect on people, animals, and plants
Juglone is so toxic only minute amounts can sicken, sedate, or kill people and animals. The concentration difference of juglone between that needed for sedation, and that causing death, is small.
© Project SOUND
http://www.bgshoppingmall.com/Brand-Names/abbyson-
living.php
So how do walnut
trees survive?
The toxin is stored in a non-toxic form (so
it doesn’t harm the walnut tree)
Juglone exists within wlanut tree cells in a non-toxic form called hydrojuglone.
Hydrojuglone is colorless and generally nontoxic, but is immediately converted to juglone by oxidation.
Upon continual contact with oxidative conditions, or tissue drying, juglone is tied up and decomposed.
When you cut open a green walnut husk, it quickly turns brown when exposed to air. This is caused by the clear, non-toxic hydrojuglone being quickly converted into the toxic, dark brown juglone in the presence of oxygen.
© Project SOUND
http://www.biologie.uni-hamburg.de/b-online/ge20/02b.gif
Allelochemicals: many modes of action
Allelopathic chemicals can be present in any part of the plant - leaves, flowers, roots, fruits, or stems.
They can also be found in the surrounding soil.
Target species are affected by these toxins in many different ways:
Inhibited shoot/root growth
Inhibited nutrient uptake
Altered symbiotic relationship [mycorrhyzae] - destroying the plant's usable source of a nutrient.
© Project SOUND
http://www.sustland.umn.edu/implement/images/trees_turf_4.gif
Why do Juglans species make juglone? At
least part of the story involves seedlings
Juglone in the husk protect the seed from being eaten. The juglone also leaches into the surrounding soil
If juglone leaks back into a walnut root, it is quickly made non-toxic again and stored.
Annual plants, garden vegetables, fruit trees, and some broad-leaf perennials can be severely damaged when juglone is in the soil. These are a seedling’s biggest competitors
Most grasses seem immune from juglone problems.
Select mycorrhizal fungi and soil microbes have been shown to be highly adapted to walnut tree control zones and the presence of juglone.
© Project SOUND
http://www.hiltonpond.org/images/WalnutBlackS
eedling01.jpg
3/11/2013
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Other native trees/large shrubs with
allelopathic properties
Oaks – Quercus spp.
Cottonwoods – Populus spp.
Manzanitas – Arctostaphylos spp.
CA Sycamore – Platanus racemosa
CA Bay Laurel - Umbellularia californica
False Indigo - Amorpha fruticosa
Eucalyptus
Tree of Heaven
© Project SOUND
http://farm1.static.flickr.com/29/101896704_625b8ccece.jpg
Dealing with allelopathy in the garden
Rake up leaves & other parts containing the chemicals(s)
Leaves, twigs, fruit husks, and wood chips from walnut trees should be well aged or completely composted before adding to a garden or landscape, if at all
Walnut stumps should be ground-down or removed from a site
Plant tolerant species under/near: Solanaceae, annuals are particularly susceptible
Grasses are usually not
Soil microorganisms ingest allelochemicals as energy sources, and metabolic decomposition can render the chemicals non-toxic to plants. When soils are well drained and aerated, a healthy population of aerobic microorganisms can accelerate this progress.
© Project SOUND
But making Juglone is expensive: is
allelopathy the only explantion?
Juglone precursors appear to be translocated from older tissue to younger tissue over time.
The immediate precursors of juglone are found in high concentrations within buds, flowers, fruit, and in the phloem (vascular system).
Juglone is also effective for protection from leaf, root and stem pests, like insects, diseases, nematodes, and grazing animals.
© Project SOUND
http://enhancedbc.tfrec.wsu.edu/CA_walnut.html
http://www.graftedwalnuts.co.uk/pest.ihtml
Pros/cons of preformed defense
chemicals (or precursor forms of them)
Positive Always ready
Mechanism often involves basic mechanisms – effective against a wide range of living things
Negative May not ever be needed – a waste of
energy & other resources
Not specific – so may not work as well against some threats
May be deleterious to the plant itself
© Project SOUND
http://c0365781.cdn2.cloudfiles.rackspacecloud.com/datas/5598254/
original/799px-155mmMustardGasShells.jpg
3/11/2013
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© Project SOUND
Southern Goldenrod – Solidago spectabilis var. confinis
http://www.jcsemple.uwaterloo.ca/goldenrod_figs.htm
© Project SOUND
Other good native Goldenrods
Solidago californica Euthamia (Solidago) occidentalis
© Project SOUND
The genus Solidago: the Goldenrods
~ 100 perennial species
Most grow in meadows, pastures, along roads & ditches in North America
Unfairly blamed for hay fever in late summer/fall - Ragweed (Ambrosia sp.), blooming at the same time but wind-pollinated, is the usual culprit.
Easily recognized by their golden flowering stalks with hundreds of small flowers; plants & flowers make nice yellow & green dyes.
Their alternate leaves are linear to lanceolate. Their margins are usually finely to sharply serrated.
CA Goldenrod - Solidago californica
Goldenrods have been used in British gardens for > 200 years
© Project SOUND
Southern Goldenrod is an herbaceous perennial
Size: 2-3 ft tall
2+ ft wide, spreading
Growth form: Stout looking herbaceous
perennial
Fall/winter deciduous; dies back to basal rosette
Foliage: Leaves lance-shaped – mostly
basal
Leaves fleshy, bright to pale green
Roots: spreads via rhizomes
© 2003 Christopher L. Christie
3/11/2013
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© Project SOUND
The genus Solidago: the Goldenrods
Propagation by wind-disseminated seed or underground rhizomes (form patches that are vegetative clones of a single plant).
Goldenrod is a companion plant, playing host to beneficial insects, repelling some pests
Goldenrods are important habitat plants for a wide range of native insects, butterflies, birds, etc.
CA Goldenrod - Solidago californica
© Project SOUND
Outside of their native range, Goldenrods
can be invasive. Why?
http://www.calflora.net/bloomingplants/southerngoldenrod.html
http://www.calflora.net/bloomingplants/southerngoldenrod.html
Teasing out whether the effect is due to allelopathy:
can be difficult Competing processes: competition for
Light
Water
Nutrients
Associated animal species may be the culprit: Pollinators, mycorrhyzae, other
beneficial species
Above or below-ground pests – Solidago may be tolerant
Vast number of chemicals produced; many not toxic (at least to other plants)
Nature of the chemicals themselves: highly changeable (oxygen; pH; exposure to other chemicals)
© Project SOUND © 2003 Christopher L. Christie
Bioassays often used to test for allelopathy
Example: testing the effects of plant tissue extracts (or specific chemicals) on the germination of seeds.
Issues in relating laboratory bioassays to allelopathic interactions in the field; allelopathy in the laboratory is not always demonstrated in the field – and vice versa
© Project SOUND
http://www.biosci.ohio-state.edu/~plantbio/osu_pcmb/pcmb_lab_resources/images/pcmb300lamb/allelopathyExperiment.jpg
http://plantecology.dbs.umt.edu/People/collaborators.html
3/11/2013
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Why are U.S. Goldenrods so invasive in
China? Could it be due to allelpathy?
Extracts were made from 12.5 g of dried leaf tissue placed in 500 ml of distilled water.
Dilutions of each extract, ranging from 0% to 100% in 10% increments were made.
Filter paper was placed in 90 mm petri plates with 20 seeds of the target species (lettuce & radish).
Five trials were run for each dilution for each goldenrod species tested.
© Project SOUND
http://posieinthevase.blogspot.com/
The answer is not exactly straightforward
Solidgo canadensis does influence soil levels of possible allelochemicals (total phenolics, total flavones and total saponins)
The chemical content and possible allelopathic effects were greater in S. canadensis from China than those from the USA as demonstrated in a field survey and a common garden experiment.
Suggests that S. canadensis has evolved to be more competitive – and possibly more allelopathic - in the introduced range
Allelopathy might significantly increase competitiveness for this invasive species.
© Project SOUND
But is the effect direct?
http://www.sciencedirect.com/science/article/pii/S0929139311000849
Plants have complex relationships with
other living things
© Project SOUND
http://www.sciencedirect.com/science/article/pii/S1360138510001007
Roots and the rhizosphere: life within the soil
© Project SOUND
http://ars.els-cdn.com/content/image/1-s2.0-S1360138512000799-gr2.jpg
http://www.cottoncrc.org.au/industry/Tools/Symptoms_Identification_Tool/Cotton_Symptoms/Allelopathy
Beneficial effect
of mycorrhyzae
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Goldenrods brought ‘novel weapons’ with them
S. canadensis altered the indigenous mycorrhizal fungal spore composition and reduced the mycorrhizal colonization of native plants one year after invasion.
The alien Goldenrod inhibited the colonization of native species and changed the indigenous mycorrhizal fungi by exuding allelochemicals.
Experimental results suggest that invasive S. canadensis may acquire spreading advantage in non-native habitat by using “novel weapons” to inhibit not only local plants but also soilborne pathogens and beneficial microbes.
© Project SOUND
http://openi.nlm.nih.gov/detailedresult.php?img=2972720_pone.0015418.g001&query=the
&fields=all&favor=none&it=none&sub=none&uniq=0&sp=none&req=4&simCollection=305
8081_1471-5945-11-5-6&npos=74&prt=3
A novel, non-native plant species (like Goldenrod)
can have many effects on the environment
© Project SOUND http://www.sciencedirect.com/science/article/pii/S016953471000145X
You may have noticed that the Sunflower
family is pretty successful
The Sunflower family (Asteraceae) is one of the most diverse families in California.
Largest plant family worldwide: contains ~ 1550 genera and 24,000 species.
Almost 200 pages of the Jepson Manual are dedicated to describing the California species alone.
© Project SOUND
http://www.wildflowers-and-weeds.com/Plant_Families/Asteraceae_pics/Asteraceae.jpg
Why are they so successful?
Possible reasons for Sunflower success
Ability to adapt well to variety of environments Plasticity: changes in phenotype
Ability to evolve quickly – change in the genes in the population
Make lots of seeds
Work well with wide range of pollinators and other beneficial species
?? Good defenses
© Project SOUND
3/11/2013
11
What types of invaders/competitors do
plants need to worry about?
Other plants (compete for water, light, nutrients)
Large herbivores
Insect herbivores
Other herbivores: mollusks
Pathogens
Fungal
Bacterial
Viral
© Project SOUND
http://www.sciencedirect.com/science/article/pii/S1360138509003008
Young leaves and other tissues are
attractive food
© Project SOUND
Why do plants make the chemicals found
in ‘essential oils’?
A wide range of reasons, many related to communication:
To attract pollinators – or the spreaders of seed (usually in flowers, fruits)
To repel herbivores – insect or other; either cue or toxin
As breakdown products from compounds used for other purposes
As protection against fungi, bacteria and viruses
To prevent other plants from growing too close ?
To communicate with other plants – via soil water or air
© Project SOUND
The ‘Double-whammy’ of injury
Tissue damage (from physical injury or herbivory) Vascular tissue: must seal off
quickly, then re-grow or re-attach if possible Water – Xylem tissue
Nutrients + other - Phloem tissue
Support tissue
Other
Secondary infection Bacterial
Fungal
Viral
© Project SOUND
http://www.tantebazar.com/gardening_histology_of_plant_part_2.php
http://ipm.ncsu.edu/corn/diseases/cornfg18.gif
http://ericwongmma.com/wp-
content/uploads/2013/01/double-
whammy.jpg
3/11/2013
12
Insects are known to be selective in their
use of plants in the sunflower family
© Project SOUND
http://ipmworld.umn.edu/chapters/charlet2.htm
Sunflower Bud Moth Long-horned Beetle
This suggests that Asteraceae may selectively deter some pest species
Certain plant compounds are effective
against insect herbivores
The most important of these are alkaloids, terpenoids, steroids, phenols, saponins and tannins
These may be an alternative source of insect control agents
© Project SOUND
http://michellebiology.blogspot.com/2012/02/54-pesticide-and-biological-control.html
The most cost effective strategy is often
to prevent/limit herbivory
Has a pleasant odor similar to pennyroyal, peppermint and camphor.
Is used in flavoring agents, in perfumery, and in aromatherapy
Insect repellant; less toxic to animals/humans than other insect repellants
© Project SOUND
Pulegone
Plants in both the Sunflower
and Mint families make a range
of chemicals to prevent/limit
herbivory
Mint family insecticidals: mostly terpenoids
Most common : monoterpenes (1,8-cineole, thujone, camphor, pulegone, menthone, others)
Plant-derived insecticides may represent alternative pest control strategies. They may degrade more rapidly than the
synthetic insecticides
May be more specific in their action
Have no genotoxicity.
Mint oil is already used as an environmentally-friendly insecticide for some common pests like wasps, hornets, ants and cockroaches
Mints also repel some birds & other large herbivores – terpenoid’s smells repel
© Project SOUND
http://www.safesolutionsinc.com/TweetMint_Gallon.jpg
3/11/2013
13
Diterpenes: another class of bioactive
terpenoids
They have 20 carbon atoms
Produced by plants and fungi; often play active role as hormones (Gibberelins)
Found in resins, gummy exudates, and in the resinous high-boiling fractions remaining after distillation of essential oils.
Diterpenes display a broad range of activities against insects
Important defense chemicals in Asteraceae, Salvia, many others
© Project SOUND
http://ars.els-cdn.com/content/image/1-s2.0-
S0367326X02001703-gr1.gif
http://www.cyberlipid.org/images/pict295.gif
monoterpenes
How do plant insecticidal chemicals work?
Feeding deterrants: Render plants unattractive or unpalatable;
Usually small chemicals; may be aromatic
Often bitter or strong tasting/smelling
Examples: alkeloids, terpenopids;
Direct toxicity: Kill insects outright; or stun them
significantly so that they are eaten by their predators
Usually function as neurotoxins
Examples:
Other, more subtle methods:
© Project SOUND
http://www.gov.mb.ca/agriculture/crops/ins
ects/images/fae02s00a.jpg
How do plant insecticidal chemicals work?
A few more subtle means
Modifying plant food absorption Modify either the food itself, the gut wall or gut flora
Often larger size
Example: Tannins – make food undigestable
Disrupting the endocrinologic balance of insects Affects reproduction
Acting as insect growth regulators, disrupting the normal process of morphogenesis May ultimately kill
Usually affects reproduction
Behaviour modifying agents Usually influence the feeding and ovipositing (egg-laying) behavior
of insects © Project SOUND
California/Big Gum Plant Grindelia camporum var. bracteosa
3/11/2013
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CA Gum Plant
Erect herbaceous perennial to 4 ft tall by 4 ft wide
Grows in clay or sandy soil:
Dry stream banks, washes
Rocky fields & plains
Sandy or alkali bottomlands
Along road sides
Grows where it gets full sun
Is stress deciduous – looses leaves during dry periods
Asteraceae species do much to protect
their young leaves & flowers
© Project SOUND
Gumplants make an interesting array of chemicals
Active compounds: resin flavanoids and diterpenes of the grindelane type.
The resin produced in multicellular glands on the surfaces of stems, leaves, and involucres - density of resin glands highest on the immature involucre bracts and lowest on the stems.
The resin is composed of grindelic acid and several of its derivatives. These labdane diterpenes are similar to the resin acids that constitute rosin, a principal product of the naval stores industry
© Project SOUND
http://www.ag.arizona.edu/~spmcl/Research/newcrops.htm
Protecting developing leaves and flowers
Grindelia species are used as food plants by the larvae of some Lepidoptera species including Flower Moths, other herbivores
Grindelane diterpenoids make up most of the resin (to 20% of the dry weight). Grindelic acid, camporic acid,
17-carboxygrindelic acid
many other diterpenoids
The diterpenoids appear to have insect repellant/insecticidal & antibiotic activity
Used as a traditional medicine (until 1960) wide range of ailments: asthma, bronchitis;
antispasmodic , urinary tract disinfectant; topical preparations to soothe burns, insect bites, skin rashes, poison ivy rash.
© Project SOUND
Balsamic scent – fairly strong
3/11/2013
15
Labdane terpinoids: typical preformed
compounds affecting a wide range of pests
Stored where likely to be needed Resin ducts of trichomes of leaves
In special plastids in epidermal or other near-surface cells
A variety of biological activities: Antibacterial, antifungal, antiprotozoal
Anti-inflammatory activities and modulation of immune cell functions – may induce long-term immunity
Significant effects on basic cell processes: Interfere with biochemical pathways of cell
death and the cell cycle phases
May explain why they affect wide range of cell types in pests (insects, microbes) and in humans
© Project SOUND
Found in many plant
parts (above/below-
ground)
Have you ever noticed how birds know
when the fruits are ripe?
© Project SOUND
http://www.gardenguides.com/633-barren-bushes-treat-
hungry-birds.html
Many fruit-berry plants use critters to
spread their seeds
Berries attract the critter
Critter eats the fruit –yum!
Critter moves around while seeds pass through the digestive tract
Seed are deposited – with a load of fertilizer – in a new place away from the parent plant
How do the birds know the fruits are ripe?
© Project SOUND
http://www.ibabuzz.com/garybogue/2009/04/15/cedar-waxwings-they-will-eat-no-toyon-berry-
before-its-time/
Cedar Waxwing gobbling up Toyon fruits
Toyon/California Christmas Berry –
Heteromeles arbutifolia
3/11/2013
16
Toyon in nature
Formerly common in the South Bay: Semi-dry slopes Back dune areas (old sand)/
coastal prairie Canyons sides
Likes some seasonal moisture Found on sandy or rocky soils Strong branching root
system Re-sprouts after a fire
This is the “red-berried
shrub” that you see on native hillsides everywhere in winter
But it’s the berries that made it famous
Formed in late summer
Turn bright red in Nov.
Beloved by birds – this is a great plant to attract Doves Cedar Waxwings Songbirds
Squirrels also like them
Makes nice holiday decorations
Berries toxic if many are eaten (particularly the unripe, uncooked berries)
Rose’s dirty little secret…poison
The highly cyanogenic nature of rosaceous stone fruits (e.g. almonds, peaches, cherries) has long been known.
The fleshy portions of the ripe fruits are basically innocuous – so we eat them
The seeds, which accumulate the cyanogenic disaccharide (R)-amygdalin, have been responsible for numerous cases of acute cyanide poisoning of humans and domesticated and wild animals
© Project SOUND http://barefootintheorchard.blogspot.com/2011/07/fridays-photos-stone-fruit.html
Yikes, cyanide?
Cyanogenic glycosides are hydrolyzed by enzymes (b-glycosidases) with the release of hydrogen cyanide.
Cyanide is one of the quickest acting poisons – stops production of energy, so heart, nervous system, breathing stop
Why aren’t the plants killed?
The glycosides are stored in vacuoles within plant cells, while the hydrolytic enzymes are found in the cytosol – fine until something injures the cells
Plants also have a way to produce the energy molecules (ATP) even when exposed to cyanide
© Project SOUND
http://www.ag.ndsu.edu/publications/landing-
pages/livestock/cyanide-poisoning-v-1150
http://leavingbio.net/cell%20structure_files/Cell%20Structure_files/image007.jpg
3/11/2013
17
Plants use several strategies to protect
themselves against their own toxins
Enzymes to quickly break down the toxins
Other ways around the toxic effects
Sequestration of toxic chemicals – lock away in a safe place
Storage as non-toxic precursor chemicals – that can be readily formed into toxins as needed
Compartmentalization Storing precursors and enzymes in separate compartments –
only released with cell/tissue damage
Storing precursors and enzymes in separate tissues -
© Project SOUND
Heteromeles – just a rose by another name?
The cyanogenic glycoside content of Toyon - as well as its resultant toxicity to insects and other herbivores - is well described.
The cyanogenic potential is highest in the newly developing leaves.
The cyanic glycosides in the pulp of immature fruits protect them from premature bird predation
During the long seed maturation process, cyanogenic glucosides are gradually shifted from pulp to seed, while pulp carbohydrates increase and fruits turn from green to red.
The birds read the cues and eat the fruit
Subsequent seed predation is prevented by the localization of cyanogenic glycosides in the seeds. It can be used (as needed) or converted to other Nitrogen compounds.
© Project SOUND
Toyon is the ‘pome’ branch of the
Rose Family along with quince, pear,
apple hawthorn, pyracantha,
cotoneaster, pomegranate, and others
http://curls-eyelashes.blogspot.com/2012/12/why-coat-apple-fruits.html
Cyanide: some herbivores more vulnerable
Substantial evidence that cyanogenic glycosides are primarily involved in defence against generalist herbivores including mammals, insects and molluscs
Rumen microorganisms produce the hydrolysis enzymes. Ruminants are therefore more susceptible to the toxic effects of cyanide
Most larger animals can detoxify in limited amounts
Heat releases HCN – cooking and dyeing
© Project SOUND
http://www.urbanoutdoorskills.com/NEWS/2011_ToyonJam.jpg
http://sunnysavagedesigns.com/wp-content/uploads/2012/11/medicinal-
clothing-sunny-savage-designs-natural-dye-toyon-hollywood-bioregional-
slow-fashion-eco.jpg
Leaves of some Chaparral plants are
indigestible as well as water-conserving
Most woody chaparral plants allocate significant energy resources to forming chemical compounds that deter herbivores or pathogens from feeding.
One of the most important such compounds is tannin. Up to twenty percent of the dry weight of leaf tissues in some shrubs may be composed of tannins.
Oak, manzanita and toyon have tannin-rich leaf tissues.
Mechanism of action: binds proteins to form non-biodegradable products – that’s why the leaves don’t degrade very quickly
© Project SOUND
‘What doesn’t kill
me will starve me’
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© Project SOUND
Silver Bush Lupine – Lupinus albifrons
© Project SOUND
Flowers that glow in
the silvery light Blooms:
Spring; usually Mar-Apr or even May our area
Long bloom season
Flowers: Typical lupine/pea shape
On stalks above the foliage
Often appear almost an iridescent blue/purple – in part due to contrast with silvery foliage
Banner spot turns from white to pink when pollinated
Seeds: pods explode (dehisc) flinging the seeds from parent plant
http://www.manhattanbeachbotanicalgarden.org/springbloomerspage2manhattanbeachbotanical
garden.html
© Project SOUND http://norenes5percent.blogspot.com/2006_03_01_archive.html
http://farm4.static.flickr.com/3175/2673277265_678df36ea6.jpg
Silvery Dune Lupine makes a
nice mid-size shrub
Nice as a smaller foundation plant
Floral fragrance – plant where you can enjoy
Quite hardy – fine for parking strips, roadways
Nice addition to rock garden Wonderful for the ‘evening
garden’ with its silvery foliage
Not the best of plants for eating
Many herbivores avoid Silver Bush lupine
Plant produces bitter-tasting toxins – the nitrogen-containing Quinolizidine alkaloids
These toxins can negatively affect livestock, causing birth defects and decreasing weight especially in young, unexperienced cattle, sheep, horses
Deer and rabbits avoid it
Deter insects leaf herbivores: aphids, beetles, thrips
The larva of the federally-endangered mission blue butterfly feed on Lupinus albifrons, becoming toxic and giving it a bitter taste to deter predators [similar to Monarch & Milkweeds].
© Project SOUND
http://www.nps.gov/goga/images/20
080328170300.jpg
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Like Toyon, Lupines also protect their
seeds with chemical poisons
Aklaoids : found in a wide variety of plants, animals, and
fungi
Many have medicinal and toxic properties.
Quinolizidine alkaloids (QAs) are known as lupine alkaloids because they mainly occur in lupinus species. Example: lupinine
Produced in green tissues; transported via phloem, stored in all organs of the plant, but particularly in reproductive organs/ seeds
Defense against pathogens and predators
© Project SOUND
Quinolizidine alkaloids (QAs) protect
lupines throughout life
Available pre-formed in seeds – protect seeds from insect herbivory
Released into the rhizosphere at germination – protect roots of young seedlings from fungal and bacterial pathogens
Induced by biotic stresses in older plants – mobilized in times/places where needed
© Project SOUND http://www.unine.ch/bota/lamun/ang/pictures/projects/logoface.jpg
© Project SOUND http://urbanext.illinois.edu/soil/SoilBiology/images/A-3.jpg
Wavy-leaf Soap Plant - Chlorogalum
pomeridianum var. pomeridianum
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Wavy-leaf Soap Plant - Chlorogalum
pomeridianum var. pomeridianum
West coast from S. OR to N. Baja
In southern CA commonly found: Grasslands Open hillsides Sheltered places in coastal
sage scrub, chaparral
Member of the Lily family
http://www.swsbm.com/Maps/Chlorogalum.gif
The Lily Family (Liliaceae)
Strap-like leaves with parallel veins (grass-like)
Flowers in ‘3’s
Bulb-forming
Includes many edible native plants (onions, wild hyacinths (brodeas), Mariposa Lilys)
http://www.wcosf.org/php/d1f.php?sci_name=Chlorogalum%20pomeridianuml
http://www.vernalpools.org/Mather/list/pages/chlpom.htm
Soap Plant
requirements
Light: full sun to part-shade
Soils: any local (well-drained best)
Water: tolerates average
to low watering Requires dry period
in late summer/fall
Nutrients: benefits from organic mulch
http://www.pacificbulbsociety.org/pbswiki/index.php/Chlorogalum
http://plants.montara.com/ListPages/FamPages/Lilia2.html
The Amole bulb:
useful organ, indeed
For the plant Storage organ for plant Reproductive organ for plant
Potential food source for animals
Many uses for humans:
Edible: must slow bake to remove bitter saponins
Makes good shampoo/soap; can even dry for stored soap
Medicinal: for cramps and rheumatism; an antiseptic rub for treating wounds, infections and sores; and an internal remedy for treating stomachache and gas.
To stun fish
Hairy covering makes good brush
Baked ‘juice’ used as glue
http://plants.montara.com/ListPages/FamPages/Lilia2.html
Saponins are responsible for
some of these uses
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Saponins: a group of
related chemicals
High-molecular-weight compounds with a fat-soluble nucleus (either a steroid or triterpenoid structure) and one or more side chains of water-soluble sugars
Despite their fairly large structural diversity these compounds share some unique biological properties:
The ability to lyse cells (erythrocytes)
To ability foam when agitated in water
Triterpene saponins are more widely distributed in nature, primarily in dicots; steroidal saponins are less common and usually found in monocots, particularly among members of such families as Liliaceae, Dioscoreaceae, Agavaceae, Alliums
© Project SOUND
Saponins are glucosides (or
glycosides): plant compounds
containing glucose (or another
sugar) combined with other non-
sugar molecules.
Saponins: why do they foam?
The ability of a saponin to foam is caused by the combination of the non-polar sapogenin and the water soluble side chain present on the molecule.
The foams tend to be stable and have been used in fire extinguishers as the foaming agent.
They are also used to produce foam in beer and are responsible for the natural foam in root beer.
They have been used as the foaming agent in toothpaste and are employed by local people where the plants occur as a shampoo and laundry detergent.
© Project SOUND
http://www.instructables.com/id/A-Homemade-
Organic-Herbal-Shampoo/step6/Blend/
Yucca root soap
http://www.indianweaving.com/wool.html
Saponins: use by plants not entirely understood
Location in plant suggests protection against herbivores and/or microbial agents
Stored in healthy plant cells as ‘preformed’ inactive precursors - readily converted into biologically active compounds in response to pathogen attack, particularly fungal.
But plant saponin content (levels/types) also seems to be dynamic, responding to many external factors:
Stimuli connected to herbivory/ attack/ pathogenic infection
Stimuli involved in plant mutualistic symbioses with rhizobial bacteria and mycorrhizal fungi.
© Project SOUND
http://www.chemicalbook.com/CAS%5CGIF%5C76296-72-
5.gif
Affect of saponins on membranes may explain
part of their effectiveness against microbes
Interact with fats (sterols) in membranes
This is followed by pore formation and loss of membrane integrity
Cell function becomes completely disrupted
© Project SOUND
Affect on spores of soil fungi
http://archive.bio.ed.ac.uk/jdeacon/microbes/saponins.htm
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Saponin effects
on fish Fish take in saponins directly into
their bloodstream through their gills.
The toxin acts on the respiratory organs of the fish without affecting their edibility. Saponins also cause the breakdown of red blood cells that help the toxin to spread quickly.
Even though the effects of the poison are powerful, they are not usually fatal. The fishermen gather the stunned fish quickly as they floated to the surface.
Fish that are washed away into untainted water revive, and can return to their pre-toxic condition.
© Project SOUND
Saponins: appear to affect cellular function
Antibacterial:
Attaches to membranes & form pores; cause cell membrane to leak
May work in concert with other chemicals (natural antibiotics)
Antifungal:
Complexes with cell membranes
Antiviral:
? Interfere with replication
]
© Project SOUND
Normal fungal spore
Fungal spores treated with a saponin
Saponins: complex mechanisms of action
Herbivory: Bitter taste (anti-feedant) – large herbivores
Cell damage may release chemicals that break down saponin precursors into more active forms
Insecticidal effects: strong insecticidals against broad range of insect types – wide range of mechanisms Anti-feedant – decreased intake
Decreased movement of food through insect gut
Blockage of sterol uptake in insect gut – insects cannot make own (need for insect hormones)
Cellular toxicity – effect on membranes
Some saponins are toxic to cold-blooded organisms and insects at particular concentrations. There is a need for further research to define the roles of these natural products in their host organisms, which have been described as "poorly understood" to date.
© Project SOUND
Saponins may provide a source of new
medicines and other products
Saponins exert a wide range of pharmacological activities including expectorant, antiinflammatory, vasoprotective, hypocholesterolemic, immunomodulatory, hypoglycaemic, molluscicidal, antifungal, antiparasitic and many others
Used as adjuvants in the production of vaccines
Many pet foods and "kitty litter" products now contain yucca extract to reduce these noxious odors.
Anti-protozoals in animals
Humans generally do not suffer severe poisoning from saponins. Our cholesterin inactivates them so that only our mucus membranes are affected. Because of this, saponins have been used in sneezing powders, emetics, and cough syrups to facilitate expectoration.
© Project SOUND
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© Project SOUND
Peninsula Onion – Allium peninsulare
©2005 Victoria Marshall
Genus Allium Many places: Europe, N. America, N. Africa and Asia
Includes the various edible perennials onions, garlics, chives, and leeks; usually both leaves & bulbs are edible
The word "allium" derived from the Greek phrase "to leap out," thereby suggesting a strong interaction between the crop and its consumer.
Has played a pivotal role in cooking worldwide; raw or cooked in many ways, produce a large variety of flavors and textures. Nutritious & tastely!
Also used as ornamentals, medicines.
Estimates of the number of species have been as low as 260, and as high as 860 – likely ~ 600
© Project SOUND
http://www.efloras.org/object_page.aspx?object_id=41473&flora_id=1
Foothills: coast & SW CA, Sierra
Locally: Catalina Isl, San Clemente Isl, Santa Monica Mtns, San Gabriels
Summer dry slopes, flats often in clay soils
Usually in Valley Grassland, Foothill Woodland, and Coastal Chaparral
© Project SOUND
Peninsula Onion – Allium peninsulare
var. franciscanum
var. peninsulare
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242102162 © Project SOUND
Peninsula Onion:
few leaves Size:
~ 1 ft tall
~ 1 ft wide
Growth form: Perennial from a true bulb
Summer/fall dormant – dies back to bulb after setting seed
Foliage: One of few leaves
Linear; channel-like (C-shape)
Medium green to blue-green
Dies back before flowering
Roots: Roots from a true bulb
©2010 Barry Breckling
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© Project SOUND
Flowers are fantastic
Blooms: in spring – usually April-May in our area; one of the later-blooming onions
Flowers: Tepals (petals/sepals) mostly
fused
Color: usually brilliant magenta; sometimes lighter and even white
In open, rather flat umbel-like clusters
©2010 Barry Breckling
©2011 Steven Perry http://en.wikipedia.org/wiki/File:Alliumpeninsulare.jpg
Propagation
Seeds: Pretty easy
May take a few rainstorms to get them to germinate – be patient
Vegetative reproduction: Bulb offsets
Bulbils – above-ground
http://farm9.staticflickr.com/8024/7390488038_d032d
f3d13_z.jpg
©2011 Steven Perry
http://www.hazmac.biz/080303/080303AlliumPeninsulare.html
© Project SOUND
Plant Requirements Soils:
Texture: clay or rocky soils in nature; most local soils, except poorly draining
pH: any local
Light: full sun to part-shade
Water: Winter: rains will be enough
in many years; supplement if long dry periods
Summer: best with none (Water Zone 1); more tolerant of a little summer water than most native bulbs
Fertilizer: none; likes poor soils
Other: leave dry leaves attached until fall
©2010 Barry Breckling
© Project SOUND
An exotic color spot
Excellent container plant – as are all native Alliums and other bulbs
Fronts of summer-dry beds
In mixed meadow/prairie
Tucked into dry places
©2011 Steven Perry
©2011 Steven Perry http://www.flickr.com/photos/xerantheu
m/5684109897/ http://www.theodorepayne.org/mediawiki/
index.php?title=Allium_peninsulare
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Why do Alliums have different shapes?
© Project SOUND
http://paulchong.net/2010/05/16/the-
magic-healing-power-of-onions/
The shape is due to variations in the Allium leaves and leaf bases. In all cases a short, flattened stem is found under these leaf bases.
The bulb is essentially fleshy leaves/leaf bases atop a short, flattened stem. The base of the leaves swell with carbohydrates from photosynthesis. The concentric swollen leaf bases make up the onion bulb.
Similarly, the swollen leaf base and its protective leaf sheath make up the clove of the garlic bulb.
Those alliums that form a pseudostem (leeks), do so because the overlapping leaf bases form a hollow stemlike structure. These leaf bases do not swell but make up the edible portion of the crop
Vegetable alliums consumed for their leaf blades (green onions; chives) typically do not form swollen structures such as bulbs.
http://flashfree.files.wordpress.com/2009/04/dreamstime_446249
2.jpg
North American
onions
In northwestern North America, numerous Indian tribes (e.g., the Salish of British Columbia) collected and consumed several species of native onions.
Onions were eaten raw, but more often steam-cooked in underground pits overnight or roasted ; some of the strong flavor and smell was lost once properly cooked
Cooked onions were eaten immediately, used as an ingredient to flavor meat and fish meals, or dried in strings for use at a later time.
In California wild onions were eaten raw after soaking in salt water, roasted, or boiled
Raw onions were rubbed on skin as an insect repellent.
© Project SOUND
What’s the deal with sulfur and plants?
Sulfur is a plant ‘secondary macronutrient’ (nutrients plants need in smaller quantities) along with calcium, silicon, magnesium
Soil sulfur comes from three sources: airborne particles, the weathering of minerals in soils, and microbial activity (decomposing organic materials)
Like all plants, alliums uptake sulfur as sulfate from the soil.
Sulfur is essential for many plant functions. A structural component of protein and peptides
Active in the conversion of inorganic N into protein
A catalyst in chlorophyll production
Promotes nodule formation in legumes
A structural component of various enzymes
© Project SOUND
http://www.omafra.gov.on.ca/english/crops/field/news/croptalk/2006/ct_060
6a2.htm
Sulfur-containing compounds
give Alliums their
characteristics flavors
Why do Alliums make these compounds?
Early Alliums probably evolved in a ‘challenging’ climate – note the storage bulbs which are often advantages in dry/variable climates.
Stored food is necessary to survive into the next season; Alliums store their survival food in bulbs.
Protection of stored food is vital for survival – so Alliums evolved some serious chemical weapons to defend it!
© Project SOUND http://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Allium_textile_drawing.png/210px-
Allium_textile_drawing.png
http://allcityanimaltrapping.blogspot.com/2010/10/gopher-removal-in-la-and-orange-county.html
3/11/2013
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What are the Allium defense chemicals
Garlic cloves produce a chemical called allicin, which is responsible for their strong pungency and aroma. Relatively large molecule; acts mainly on direct
contact with the eater, a plant version of hand-to-hand combat.
The flat-leafed Chinese or garlic chives produces a small amount of garlicky allicin, but much more of a different weapon that has a milder, cabbage-like aroma.
Onions, shallots, scallions and leeks produce a sulfur molecule that’s a long-distance weapon - the lachrymatory factor - it makes people’s eyes water.
© Project SOUND
So why do onions smell
mild until they are injured?
Why don’t they just smell
strong all the time?
http://www.capital-cooking.com/blog/?p=969
How Alliums insure that the compounds
are ready when needed
Sulfate is used to form the allium flavor precursors, known collectively as the alk(en)yl-L-cysteine sulfoxides or ACSOs.
The ACSOs are present in the mesophyll storage cells, inside the cell's cytoplasm.
Each allium crop is characterized by a different number and ratio of these ACSOs, which ultimately determine its flavor.
© Project SOUND
http://www.meritnation.com/ask-answer/question/what-is-mesophyll-cell/nutrition-in-
plants/2216347
Cross-section of a leaf –
much magnified
How do Alliums insure that the
compounds are ready when needed?
The ACSOs are actually ‘flavor precursors’. They do not impart flavors directly
The chemical reaction begins when the enzyme alliinase, stored in the bundle sheath cells and protected from the ACSOs by a membrane, comes into contact with the ACSOs after tissues are cut.
The scent of an unchopped onion bulb is completely different from after tissues have been chopped; the enzyme reaction changes the ACSOs into thiosulfinates, which are actually responsible for allium flavors.
© Project SOUND
http://plantcellbiology.masters.grkraj.org/html/Plant_Cell_Biochemistry_
And_Metabolism6-Plant_Cell_Energy_transductions2-
Photosynthesis.htm
http://www.healthybusiness.co.za/GNLD%20Products%20Guide/nutrition-1/n16.html
Who are the intended targets? Larger
(mammalian) herbivores/ omnivores
Chemicals are highly irritating, and
discourage most creatures from coming back for seconds lachrymatory factor is small and light – an
airborn molecule that is perceived by the nose, the eyes, the tongue, and the skin.
Prolonged contact will blister/burn the skin.
Contact (or eating) causes chemicals to pass right through the skin and into the blood. Not very toxic to most larger pests
Damage the red blood cells of dogs and cats.
© Project SOUND
http://images.northrup.org/picture/xl/skunk/baby-
skunk%20(27).jpg
Chemicals meant to
deter larger pests
by direct contact
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What about humans? Aren’t we targets?
The human connections with Alliums likely go back a long way – we’ve learned how to deal with them
Allium chemicals are short-lived ; heat and exposure to other chemicals speeds up the process.
Most humans process Alliums before eating; this converts the irritating chemicals into something more palatable:
Boiling chopped garlic results in the formation of various sulfides.
Sautéing in oil produces the vinyl dithiins and ajoene
© Project SOUND
http://images.teamsugar.com/files/upl1/1/12981/27_2008/wet-saute.jpg
http://onioneffects.blogspot.com/2010/01/while-crying-when-cutting-onions.html
Some insect herbivores appear to be repelled
by Alliums – or worse
Chemical location studies: In mature Alliums, alliin precursors are
concentrated in the bulbs
In premature plants, most may be found in the leaves and stems.
Several compounds shown to be toxic to beetles and other insects in stored food products - superior to methyl bromide (widely used fumigant)
Not all insects deterred: Various Allium species are used as larval food plants by some Lepidoptera, including some common moths.
© Project SOUND
http://www.ukflymines.co.uk/Images/gallery/Acrolep
iopsis_assectella/Acrolepiopsis_assectella_1.jpg
The effect of thiosulfinates on microbes has
been puzzling Thiosulfinates have different degrees
of antibacterial and antifungal inhibition
Antibacterial activities against a variety of Gram-negative and Gram-positive bacteria – but not in all studies
Appear to amplify the effects of known antifungal/ anti-bacterial compounds
Direct affect of thiosulfinates has been difficult to understand: ? Direct effect on microbial enzymes
? Decreased production of microbial enzymes
? Kill microbial cells directly
© Project SOUND
http://img.mit.edu/newsoffice/images/article_images/201009
30171318-0.jpg
Thiosulfinates act at the cellular level due
to their sulfur-containing properties
Allicin easily penetrates biological membranes
Reacts rapidly with other sulfur-containing molecules within cells, changing their physical structure by changing/dissolving key bonds - affects their functions as enzymes and structural proteins
Allicin affects the basic structure and functions of cells: decreases effects of enzymes and interferes with microtubule assembly by modifying SH groups in tubulin
© Project SOUND
tubulin
http://www.ipbs.fr/local/cache-vignettes/L315xH500/structure_cristallographique_proteine_gcp4_-c6d6c.jpg
3/11/2013
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© Project SOUND
http://ars.els-cdn.com/content/image/1-s2.0-S0167779998011895-gr2.jpg
Injury/invasion sets off a chain
reaction
Early defense mechanisms: constitutive/preformed phytoanticipins
Local defense mechanisms: induced products/chemicals (phytoalexins)
Systemic defense: Long term ‘immunity’ (induced)
Thiosulfinates act at the
cellular level due to their
sulfur-containing properties
Likely explains all of allicin effects on microbes
Modify key microbial enzymes needed for invasion
Immobilize/disrupt cell functions, then other compounds can come in for the kill – explains why allicin increases the effects of known fungicides and bacteriocides
Stops cell reproduction/replication
Ultimately causes microbe cell death
May also explain: Plant cell mortality in affected area - limits the area of infection
Stimulating long-term induced resistance mechanisms
© Project SOUND
Types of plant invaders/competitors
Other plants (compete for water, light, nutrients)
Large herbivores
Insect herbivores
Other herbivores: mollusks
Microbial pathogens
Fungal
Bacterial
Viral
© Project SOUND
http://king.portlandschools.org/files/houses/y2/animalmaineia/files/species/wfrogkm/foodweb/food%20web.html
http://www.redorbit.com/media/gallery/national-science-foundation-
gallery/medium/183_2e89a9412c11ae4335fb2d3595389454.jpg
Defenses cost – money or energy
Self-toxicity/injury
Resources lost for other uses
Effects on other pathogens/ insects
Effects on beneficial organisms
© Project SOUND
http://www.washingtonpost.com/blogs/wonkblog/wp/2013/01/07/everything-
chuck-hagel-needs-to-know-about-the-defense-budget-in-charts/
http://www.sciencedirect.com/science/article/pii/S0065229609510154
3/11/2013
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Plant allocation of energy to defense
Concentrate resources on defending most vulnerable parts Young tissues
Reproductive organs
Seeds
Protect against self-toxicity/harm
Have both broad-range and specific defenses
Produce pre-formed defenses only against the most common types of pests/pathogens
Spend enough – but not so much that it effects other functions (growth; development; reproduction)
© Project SOUND
http://www.furryelephant.com/lib/swf/radioactivity/preview/re6Ms178.jpg
http://blog.optimizecode.com/wp-content/uploads/2010/07/cost.jpg
The next time you visit a peaceful garden…
© Project SOUND
http://images2.wikia.nocookie.net/__cb20071004195640/starwars/images/3/3e/SPHAT-concentratedfire.jpg
Remember, it’s a war out there!