biol235z Flashcards

Question

plant secondary metabolites?

Answer 1

what are they for? -uv protection -allelopathy -nutrient cycling

Answer 2

these metabolites may solve more then one purpose edwards (1989) natural defence came up with neutral defence could have evolved along time ago but now has another benefit. could have been expressed for one thing but now protects against herbivory. if you can demonstrate a protective role for the plant then the secondary defence acts as a anti herbivore protection.

Answer 3

PSMs are not linked to growth or development and are taxonomically restricted, but its a chemical defence if protective.

Answer 4

1980's the big three *nitrogen-containing *phenolic compounds *terpenes (carbon based)

Answer 5

largest class of PSM synthesised from acetyl-CoA produced in an isopreme unit, lego block of terpene, this joins together creating (2)monoterpenes, sesquiterdepine(3), diterpene(4) examples: pyrethriods (cyrysanthemum) used in head lice killer monoterpenes (pine smell toilet cleaner) mant terpenoids are smelly pine terpenes through the ages iason et al (2011) how different terpines effect different herbs at different species times *trees are attacked by different herbivores throughout their life-history. volitile protein changes, through the life cycle detering different herbviores at different stages of growth

Answer 6

10k different compounds aromatic ring in higher plants synthesised mainly via the shikimic acid lignin-provides mechanical support but also reduces digestibility (its why plants are cruddy) strutural tannins- are both feeding deterrents and have toxic impacts on growth and survival make up tea, apples, wine (shark taste) phenolics down under a general pattern emerges for proteaceae seedlings attacked by vertebrates planted seedlings out in the field and looked at rates of attacked out in the field and the amount of phenolics produced the more phenolics produced the less likely to get eaten negative assocation between phenolic

Answer 7

chemically and found in about 20% of vascualr plants (allocation choices) alkaloids are characterised by the hetercyclic ring a variety of human use (fabacce) alkaloids in action hanley et al started at the seedling stage sowed in 6 different see species allowed slugs and snails to feed freely other not only grazed at seedling stage results the stuff that was grazed is dominated by ragwort and grasses highly grazed were weedy, but outcompeted in the weedy section even tho slugs wouldnt eat ragwort putting all effort into chemical defences and not on growth therefore out competed by the weeds (dandelions)

Answer 8

common in fabaseae and rosaeae (almonds) holding cyanoid in the tissues inly released when eaten probelm: its a respiratory poision and plants also do respiratory therefore they keep an enxyme and glycosentate only mix if the plant is destoryed *describe futher lythic enzymes also catalyse this process (spit) other bits are defended by herbivores flowers hakeas- take a lot of effort to create produce big red obvious flowers because they are bird pollinated and need to be visible. this accessabilty makes them a target too, therefore they are laced full with cyanoid . Pollinating birds dont effect the membranes just pollinate

Answer 9

what makes cabbages smell of cabbages similar principle to cyanoid in hakeas decompostion of aglycone releases sulphate (catalyised by spit of the herbivore) GLS and enzymes again are stored separately the white response to GLS (cabbage white butterfly) gravid females use the highly volatile isothicynate smell to locate plants (renwick 1992) can detoxify the chemicals and thus get the food resource for themselves and other predators wont come near them due to the alcayanoids larvae rediret the GLS hydrolysis reaction

Answer 10

despite an array of diverse chemical weapons, call plants get eaten 1960's- evol arm race plant responds, then herb responds etc back and forth *milk weed *south african catapillar shows the tropical diversity in tropical regions

Answer 11

structural defence- the poor relation all the basics that apply to chemical is logical to structural.

Answer 12

structural support, reduce water loss, thermal protection, uv protection strauss and agrawal (1999) a trait can be viewed as a defence even though defence is not its primary function

Answer 13

Any morpholical or anatomical trait that confers a fitness advantgae to the plant by directly deterring herbivores from feeding on it (hanley at al 2007)

Answer 14

spines: sharp-pointed, petioles, midribs, veins or stipules (holly-highly rolled lumps of lignin. Leaf mod) Thorns: sharp-pointed, woody branches. Prevent herbivores by climbing. Can be seen in seba spines- better against big herbivores how do we know this: evidence of this give herbivores plants with or without spines, given to kangeroos in captivity. (hanley et al 2007) hakea species give same plant without the spikes and the twig without spines were more eaten. other studies: thorns on acacia in kenya removal of thorns from african acacia= 74% of branches then eaten. Reduce in recovery for the non-defenced plant.

Answer 15

increase graph grazing increase in thorns in this area

Answer 16

layer sof trichomes on leaves, stems and flowers. example of species: stinging nettles trichome types: morphology spiral, straight, stellate, hooked. can also produce a chemical more subtle in how it works: -reduces tissue ingestation -reduce obiposition (butterflies can get ovipositor into a nice spot) -reduce movement/trap insects most effective on small invertebrate herbivores evidence the defensive role: induced pubesence by herbivore attack Traw and dawson (2003) using black mustard leaf hairs were more dense, induction of more and bigger leaf hairs

Answer 17

hardness due to high lignin and cellulose content (former is hard to digest) if a plant builds enough of these it creates a strucural barrier to attack somewhat distasteful example: dwarf palm/holly makes the point that the idea of sclerophylly. common in mediterranean-climate regions

Answer 18

-prevent water loss -protection cells against high UV -layer of hazy chemical above the leaf takes some of the UV -when the herbivores are around it prevents herbivore consumption (defence against herv attack) -more large herbivores -protect against uv -prevent water loss sweets of co-adaptive traits no way of knowing which is the most important

Answer 19

silicon-based plants absorb monosilicic acid (si(OH)4) from soil a sweet of chemicals plants above and below ground transported to the shoot epidermis to form biogenic silica this forms opaline phytoliths phytolithos are the most common in poaceae (cuts when pulling on grass) increased leaf abrasiveness means more tooth/mouthpart wear;reduced digestibility -good defence against mammal and invertebrate herbivores *feed grass hoppers with this it even wears down their mouth parts grasses and voles massey & hartley (2009) varied the silica content soils if its offered where more silica is taken up the abrasiveness of the grasses increased thus the attack by herbivores such as voles declined. same paper also shows more silica defence once herb attack is experiecned

Answer 20

not just above ground parts that are defended but also below ground parts defending bulb attack even below ground many inter-tidal algae secrete calcium carbonate fell gritty ehrn you touch them, coraline algae. Reduces intertidal gastropods attack. Structural defences vs chemical defences

Answer 21

takes a lot of effort in a resource limiting environment producing these flueorsnces leaves you vunerable for unwanted attention from emus etc therefore they produce lots of cyanide to prevent attack 25-30% produce these big atttractive flowers most make generally white/ light pink clour but these have rolled spinence of leaves spines protecting from attack but what polliantes them? insects acts as pollinator 2 ways of being a hakea bird pollinated: big without spines, but low level of physical defence but high chemical defence insect pollinated: inaccessible infloresnces not as much chemical defences thus trade offs between pollination

Answer 22

if hakea infloresences are defended by spines what about fruits? more devleoped on insect pollinated species bird pollinated fruits tend to be bigger and tougher then insect pollinated. have to be tough as a fruit due to parrot herbovires that want the seeds within the capsules. so defence seems to be water tight but cockatoos think differently regenerate after fire but a herbivore will overcome a defence sooner or later- arms race however water tight a defence something will overcome it selection pressures: however clever the plant is for allocation of choices less resource then to growth and reproduction, anti pathogen defence, cold.

Answer 23

hypotheses: optimal defence (OD), carbon:nutrient balance, growth rate (GR) and growth- differentation (GDB). All serving as frameworks for investigating the patterns of plant defense against herbivores. OD- served as a main framework for investigation of genotypic contribution of CNB hypothesis expression of plant defence. GR- explains intrinsic growth rate of plants shaped evolutionary by resource avaliabilty affects defensive patterns GDB- recognises the constant phyisological tradeoffs between growth and differentation at the cellular and tissue levels relative to the selective pressures of resource avalibility.

Answer 24

The final consideration is cost: how much will a particular defensive strategy cost a plant in energy and materials? This is particularly important, as energy spent on defense cannot be used for other functions, such as reproduction and growth. The optimal defense hypothesis predicts that plants will allocate more energy towards defense when the benefits of protection outweigh the costs, specifically in situations where there is high herbivore pressure

Answer 25

The tolerance of plants to herbivory reflects the degree to which a plant can regrow and reproduce after damage from herbivores. How sessile plants defend themselves against attack from herbivores: olerance, the ability of plants to regrow and/or reproduce after herbivory, could serve as such a defense. This ability has been investigated by agriculturists, who were stimulated by the need to estimate the economic costs of herbivory; however, plant tolerance to her- bivory in natural populations has only recently received attention. *terrestrial plants in natural communities sustain 18% damage in the field *The degree of tolerance to herbivory is not necessarily directly related to plant fitness. For example, a plant that compensates completely for herbivore damage could still have lower overall fitness than less tolerant genotypes with high fitness in both damaged and undamaged states (compare genotype F versus C, D and E in Fig. 1).

Answer 26

Defense: any trait that confers a fitness benefit to the plant in the presence of herbivores. A trait can be viewed as defensive even though defense is not its primary function. For example, the primary role of flavonoids, known deterrents of herbivores, might be to protect leaf tissues from UV damage. Resistance: any plant trait that reduces the preference or performance of herbivores43. Tolerance: the degree to which plant fitness is affected by herbivore damage relative to fitness in the undamaged state. Tolerance can be estimated only from a group of related or cloned plants because the fitness of an individual plant cannot be examined in both damaged and undamaged states. Compensation: a term used to refer to the degree of tolerance exhibited by plants. If related damaged and undamaged plants have the same fitness, then that family has the ability to compensate fully for herbivory. If damaged plants have greater fitness than their undamaged relatives, then plants have overcompensated and if they have lower fitness, they have undercompensated for herbivory.

Answer 27

feedback loops: For example, removal of leaf tissue by herbivores decreases leaf area available for photosynthesis, but can also increase light levels to previously shaded portions of the canopy, thereby increasing photosynthetic capacity in remaining leaves

Answer 28

what are the 3 principle trade offs here? *bird pollinated: - colourful, no/less physical defence, influorecences: accessiblity (need to be highly accessible for birds to be able to access): chemical defences *insect pollinated -less colourful, more physical defence. inaccessible inflorescences

Answer 29

4 main hypothesis: which one captivates the best? *GR:

Answer 30

what are the three elements of ODH? *risk of attack (apparancy) how obvious to the herbivore *cost of plant defence *value of plant part having to be defended which of a mediterranean shrub or arable annual is more apparent? poppy- doesnt live long so get through life history. shrub: is there for longer so it has more of a risk longer think of an example where apparent high-value plant parts are well defended? *wild parnsips: flowers *hacea (big red flowers)

Answer 31

*apparaency is difficult to quantify (what animals will be more attracted then others) no consistent evidence for link between apparency and defence allocation in literature. Thus cant quantify. only worth incurring defence costs when herbivores present, else theres a fitness cost.

Answer 32

defence is determind by plant growth rate- in turn determind by available resources GRH predicts that allocation to defence increases as growth potential decreases get reproduction bit down then allocate resources against defence. thus plants in resource-poor areas with inherently slow-growth rates as theres not alot of resource there (water, soil nutrients) thus cant turn over roots/shoots very quickly.

Answer 33

how does light limitation affect allocation to induced defence? competitive shade-intolerant fast growth plant species then rates of induction exihibit higher induction then slow-growing (shade tolerant) species according to GRH which of a med shrub or arable annual is best defended? med shrub: slow growth effort, makes sense to allocate defence structures

Answer 34

allocation determind by the carbon: nitrogen ratio plant growth in nitrogen-deficient soils more limited that p/s-plants. plants allocate excess c to carbon based defences *resource avalibility plant isnt wasteful, where not light limited then excess carbon is moved somewhere (lignify structure) *maybe this is why alkanid limited: drugs, tobacco what happens to the carbon-nutrient interaction if we increase atmospheric co2 concentrations? (nitrogen lacking) *decrease relative balance in the plant *excess carbon turned into plant structural defence. more cruddy in eco2 as lignocellulose allocation increases (herbivore preferences change)

Answer 35

what is the dilemnna at the heart of GDBH? the trade off grow or defend *resource acquisition but in doing so they're taking away from defence. compete vs herbivory defence (grow quickly and acquire quickly) more competive ability *phyisological trade- off between growth what is the cellular basis of this theory? need to be bigger differentiation- trade of inherent growth-cell division and enlargement

Answer 36

where resources limit phosynthesis, carbon supply limits growth and defence. as resources increase photosynthesis requirments are met allowing CHO. But not enough to support growth, so C compounds used synthesise carbon based defence (phenolics, tanins) optimal defence GDBH is most mature hypothesis

Answer 37

many plants can simply re-grow (compensate) following tissue loss- how does this fit into plant defence theory? *plants have the ability to tolerate in this framework. how plants quickly reallocate resources

Answer 38

tolerance/escape low nutritional quality nutrition and defense

biol235z Flashcards

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