Plants - Taiz Ch. 13

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Secondary metabolites

cutin suberin waxes

provide protection against pathogens already on the plant surface and help to reduce water loss.

terpene phenolic nitrogen

3 major groups of secondary metabolites

terpene

composed of five carbon isoprene units, are toxins and feeding deterrents to many herbivores

phenolic

synthesized primarily from products of the shikimic acid pathway

lignin

a phenolic compound, strengthens cell wall

flavonoid

pigment function as shields against harmful UV radiation and as attractants for pollinators and fruit dispersers.

nitrogen

these compounds synthesized principally from common amino acids.

jasmonic

plant defenses against insect herbivores involve the induction of various secondary metabolites and proteinaceous inhibitors of digestion through signaling pathways involving _____acid.

cutin

macromolecule, polymer consisting of many long chain fatty acids that are attached to each other by ester linkages

cuticle

cutin is the principal component of the _____.

cuticle

A multilayered secreted structure that coats the outer cell walls of the epidermis on the aerial parts of all herbaceous plants.

wax cutin cuticular

cuticle is composed of a top coating of ___, a thick middle layer containing ___ embedded in wax, and a lower layer formed of cutin, and wax blended with the cell wall substances pectin, cellulose and other carbohydrates (the ____ layer)

wax

not macromolecules, complex mixtures of long-chain acyl lipids that are extremely hydrophobic.

cutinase

many fungi penetrate directly through the plant surface by mechanical means - others produce ___, an enzyme that hydrolyzes cutin and thus facilitates entry into the plant

terpene

largest class of secondary products

insoluble

terpenes are soluble/insoluble in water

acetyl coA

terpenes are synthesized from ___ or glycolytic intermediates

terpenes

all ______ are derived from the union of five-carbon elements (aka C5 units) that have the branched carbon skeleton of isopentane

isoprene

basic structural elements of terpenes are sometimes called _____ units

monoterpene

ten carbon terpenes contain two c5 units

sesquiterpene

15 carbon terpenes, three c5 units

diterpene

20 carbon terpene, four c5 units

tetraterpene

40 carbon terpene, eight c5 units

mevalonic mep

Terpenes are biosynthesized from primary metabolites in at least two different ways

mevalonic acid

three molecules of acetyl co-a are joined together stepwise to form

isopentenyl diphosphate

mevalonic acid is phosphorlyated, decarboxylated and dehydrated to yield IPP

methylerythritol phosphate

IPP can also be formed from intermediates of glycolysis or the photosynthetic carbon reduction cycle via a seperate set of reactions called the MEP

plastids

MEP operates in

gibberellins

certain terpenoids have well characterized function in plant growth/development - can be considered primary rather than secondary metabolites. This important plant hormone are diterpenes

abscisic acid

This hormone is a c15 terpene produced by degradation of a carotenoid precursor.

acetyl coA

starting material for terpenoid in the mevalonate pathway

glyceraldehyde and pyruvate

starting material for terpenoid in the MEP pathway

methylerythritol phosphate pathway

Acronym for MEP

pyrethroid

monoterpene ester that occur in leaves and flowers of chrysanthemum species, show insectidicial activity

chlorophyll

terpene derived side chains such as phytol side chain of _____ help anchor certain molecules in membranes.

phytoecdysone

group of plant steroids that have the same basic structure as insect molting hormones

cardenolides

glycosides (compounds containing an attached sugar) that taste bitter and are extremely toxic to higher animals. Have dramatic effect on heart muscle through their influence on Na+/K+ activated ATPases. Extracts from foxglove prescribed as heart medication.

jasmonic acid

compound that functions as a powerful feeding deterrent against mammalian grazers

salicylic acid

phenolic compound responsible for systemic acquired resistance to pathogens

phytoalexins

secondary compounds that protect plants against invading pathogens

terpene

plant growth regulator such as gibberellins or abscisic acid

nitrogen

potent neurotoxins such as nicotine and coniine

terpene

insect repellents/deterrents such as pyrethroids or limonoids

phenolic

light absorbing defenses such as flavonoids or phototoxic coumarins

nitrogen

cyanogenic defensive compounds

Water loss
Pathogen entry
"Dirt"

Cuticle forms a barrier to:

-Have no generally recognized direct roles in primary metabolism
-May be restricted to distinct groups of plants
-May protect against enemies
-May serve as attractants
-May function in plant-plant or plant-microbe interactions

What are the possible roles of secondary metabolites?

Secondary metabolites

_____ have no generally recognized direct roles in primary metabolism

-Can function as plant growth regulators
(gibberellins, abscisic acid)
-May serve to transport or anchor
macromolecules w/in cells
-Can be toxic or otherwise defend
(pyrethroids, resins, essential oils,
phytoecdysones, cardenolides,
saponins)

Discuss terpenoids.

Monoterpenes
sesquiterpenes

_____ and _____ are commonly found in glandular hairs.

glandular hairs

Monoterpenes and sesquiterpenes are commonly found in _____.

wax

Surface _____ deposits, which form the top layer of the cuticle, adopt different forms.

cuticle

Surface wax deposits, which form the top layer of the _____, adopt different forms.

Can serve as signals of stress
Can become toxic in light (photoxicity)
Can inhibit metabolism of other plants
Are precursors to lignin synthesis
Can function as pigments (flavonoids)
Can defend against pathogens
(isoflavonoids) or herbivores (tannins)

Discuss phenolics.

biosynthesized

Plant phenolics are _____ in several different ways.

roles

Simple phenolic compounds play a great diversity of _____ in plants.

Alkaloids

_____ are a diverse group of secondary metabolites that contain nitrogen.

nitrogen

Alkaloids are a diverse group of secondary metabolites that contain _____.

nicotinic acid (niacin)

Nicotine biosynthesis begins with the biosynthesis of the _____.

Nicotine

_____ biosynthesis begins with the biosynthesis of the nicotinic acid (niacin).

Two

_____ forms of pyrrolizidine alkaloids occur in nature.

cyanogenic glycosides

Enzyme-catalyzed hydrolysis of _____ releases hydrogen cyanide.

hydrogen cyanide

Enzyme-catalyzed hydrolysis of cyanogenic glycosides releases _____.

glucosinolates

Hydrolysis of _____ produces mustard-smelling volatiles.

mustard-smelling volatiles

Hydrolysis of glucosinolates produces _____.

infection

Many types of antipathogen defense are induced by _____.

antipathogen

Many types of _____ defense are induced by infection

increase resistance to future pathogen attack.

Initial pathogen infection may.....

increase

Initial pathogen infection may _____ resistance to future pathogen attack.

Straight-chain alkanes: CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

cutin, waxes, and suberin are composed of:

cutin
suberin
waxes

All plant parts exposed to the atmosphere are coated with layers of lipid material that reduce water loss and help block the entry of pathogenic fungi and bacteria. The principal types of coatings are _____, _____, and _____.

lipid

All plant parts exposed to the atmosphere are coated with layers of _____ material that reduce water loss and help block the entry of pathogenic fungi and bacteria. The principal types of coatings are cutin, suberin, and waxes

water
pathogenic fungi
bacteria

All plant parts exposed to the atmosphere are coated with layers of lipid material that reduce _____ loss and help block the entry of _____ and _____. The principal types of coatings are cutin, suberin, and waxes

Cutin
suberin
Waxes

_____ is found on most above ground parts; _____ is present on underground parts, woody stems, and healed wounds. _____ are associated with both cutin and suberin.

-above ground parts
-underground parts, woody stems, and healed wounds
-both cutin and suberin

Cutin is found on most _____; suberin is present on _____. Waxes are associated with _____.

-long-chain fatty acids
-16:0
-middle
-end opposite the carboxylic acid function

Cutin is a macromolecule, a polymer consisting of many _____that are attached to one another by ester linkages, creating a rigid three-dimensional network. Cutin is formed from _____ and 18:1 fatty acids with hydroxyl or epoxide groups situated either in the _____ of the chain or at the _____.

ester
18:1
hydroxyl
epoxide

Cutin is a macromolecule, a polymer consisting of many long-chain fatty acids that are attached to one another by _____ linkages, creating a rigid three-dimensional network. Cutin is formed from 16:0 and _____ fatty acids with _____ or _____ groups situated either in the middle of the chain or at the end opposite the carboxylic acid function

-secreted
-aerial
-wax
-cutin embedded in wax
-cutin and wax blended with the cell wall substances pectin, cellulose, and other carbohydrates
-long-chain hydrocarbons

Cutin is a principal constituent of the cuticle, a multilayered _____ structure that coats the outer cell walls of the epidermis on the _____ parts of all herbaceous plants. The cuticle is composed of a top coating of _____, a thick middle layer containing _____ (the cuticle proper), and a lower layer formed of (the cuticular layer). It has been suggested that in addition to cutin, the cuticle may contain a second lipid polymer made up of _____, which has been named cutan.

epidermis
cuticle proper
cuticular layer
cutan

Cutin is a principal constituent of the cuticle, a multilayered secreted structure that coats the outer cell walls of the _____ on the aerial parts of all herbaceous plants. The cuticle is composed of a top coating of wax, a thick middle layer containing cutin embedded in wax (the _____), and a lower layer formed of cutin and wax blended with the cell wall substances pectin, cellulose, and other carbohydrates (the _____). It has been suggested that in addition to cutin, the cuticle may contain a second lipid polymer made up of long-chain hydrocarbons, which has been named _____.

complex mixtures of long-chain acyl lipids that are extremely hydrophobic.

Waxes are not macromolecules, but rather.....

straight-chain alkanes and alcohols of 25 to 35 carbon atoms.

The most common components of waxes are.....

waxes

Long-chain aldehydes, ketones, esters, and free fatty acids are also found in _____.

cuticle

The waxes of the _____ are synthesized by epidermal cells.

crystallizes

The wax that forms the outer coating of the cuticle often _____ in an intricate pattern of rods, tubes, or plates

water repellency
water
water droplets
lotus effect

The wax that forms the outer coating of the cuticle often crystallizes in an intricate pattern of rods, tubes, or plates. Certain patterns of these microstructures enhance _____ by increasing the roughness of the wax surface. This roughness prevents _____ from forming large contact areas with, and thus from adhering to, the already hydrophobic surface. Thus _____ form instantly on contact and carry away contaminating particles, cleansing the plant's surface. This phenomenon was first described for the leaves of the leguminous lotus Lotus japonicus and, for that reason, it is sometimes referred to as the "_____."

-roughness of the wax surface
-roughness
-carry away contaminating particles, cleansing the plant's surface

The wax that forms the outer coating of the cuticle often crystallizes in an intricate pattern of rods, tubes, or plates Certain patterns of these microstructures enhance water repellency by increasing the _____. This _____ prevents water from forming large contact areas with and, thus from adhering to, the already hydrophobic surface. Thus water droplets form instantly on contact and _____.

Suberin

_____ is a polymer whose structure is poorly understood.

dicarboxylic acids, more long-chain components, and a significant proportion of phenolic compounds as part of its structure.

Like cutin, suberin is formed from hydroxy or epoxy fatty acids joined by ester linkages. However, suberin differs from cutin in that it has.....

suberin
suberin

Like cutin, _____ is formed from hydroxy or epoxy fatty acids joined by ester linkages. However, _____ differs from cutin in that it has dicarboxylic acids, more long-chain components, and a significant proportion of phenolic compounds as part of its structure.

-hydroxy
-epoxy fatty acids
-ester
-dicarboxylic acids
-long-chain
-phenolic

Like cutin, suberin is formed from _____ or _____ joined by _____ linkages. However, suberin differs from cutin in that it has _____, more _____ components, and a significant proportion of _____ compounds as part of its structure.

cell wall

Suberin is a _____ constituent found in many locations throughout the plant.

-cork cells of the periderm
-abscission
-damaged by disease or wounding

Suberin is a principal component of the outer cell walls of all underground organs and is associated with the _____, the tissue that forms the outer bark of stems and roots during secondary growth of woody plants. Suberin also forms at sites of leaf _____ and in areas _____.

-underground
-the outer bark of stems and roots during secondary growth of woody plants

Suberin is a principal component of the outer cell walls of all _____ organs and is associated with the cork cells of the periderm, the tissue that forms _____. Suberin also forms at sites of leaf abscission and in areas damaged by disease or wounding

water
pathogens

Cutin, suberin, and their associated waxes form barriers between the plant and its environment that function to keep _____ in and _____ out.

transpiration
stomata
environmental

The cuticle is very effective at limiting water loss from aerial parts of the plant, but it does not block _____ completely: Even with the _____ closed, some water is lost. The thickness of the cuticle varies with _____ conditions.

thicker
thick
thicknesses

Plant species native to arid regions typically have ____ cuticles than do plants from moist habitats, but plants from moist habitats often develop _____ cuticles when grown under dry conditions. Similarly, sun leaves and shade leaves of the same canopy often show different cuticle _____.

arid
moist
dry
canopy

Plant species native to _____ regions typically have thicker cuticles than do plants from moist habitats, but plants from _____ habitats often develop thick cuticles when grown under _____ conditions. Similarly, sun leaves and shade leaves of the same _____ often show different cuticle thicknesses.

fungi
phytoalexin
hypersensitive
fungi
cutinase

The cuticle and suberized tissues are both important in excluding _____ and bacteria, although they do not appear to be as important in pathogen resistance as some other defenses, such as _____ production and the _____ response. Many _____ penetrate the plant surface directly by mechanical means. Others produce _____, an enzyme that hydrolyzes cutin and thus facilitates entry into the plant.

cuticle
suberized
bacteria
mechanical
hydrolyzes cutin

The _____ and _____ tissues are both important in excluding fungi and _____, although they do not appear to be as important in pathogen resistance as some other defenses, such as phytoalexin production and the hypersensitive response. Many fungi penetrate the plant surface directly by _____ means. Others produce cutinase, an enzyme that _____ and thus facilitates entry into the plant.

Digitoxigenin
digitanides
D-digitoxose
acetyldigitoxose
saponins

_____ is the aglycone (sugarless) triterpene portion of the naturally occurring _____, which contain one molecule of the rare sugar _____ and one molecule of _____. The yam Dioscorea contains _____—e.g., yamogenin—that are widely used as starting materials in the synthesis of progesterone-like compounds for birth control pills.

aglycone
triterpene
progesterone-like

Digitoxigenin is the _____ (sugarless) _____ portion of the naturally occurring digitanides, which contain one molecule of the rare sugar D-digitoxose and one molecule of acetyldigitoxose. The yam Dioscorea contains saponins—e.g., yamogenin—that are widely used as starting materials in the synthesis of _____ compounds for birth control pills.

phenolics

Plant _____ are biosynthesized by several different routes and, thus, constitute a heterogeneous group from a metabolic point of view. Two basic pathways are involved: the shikimic acid pathway and the malonic acid pathway.

the shikimic acid pathway and the malonic acid pathway.

Plant phenolics are biosynthesized by several different routes and thus constitute a heterogeneous group from a metabolic point of view. Two basic pathways are involved:

phenolics

The shikimic acid pathway participates in the biosynthesis of most plant _____.

shikimic acid

The _____ pathway participates in the biosynthesis of most plant phenolics.

malonic acid

The _____ pathway, although an important source of phenolic secondary products in fungi and bacteria, is of less significance in higher plants.

carbohydrate precursors derived from the pentose phosphate pathway (D-erythrose-4-phosphate) and glycolysis (phosphoenolpyruvic acid).

In the shikimic acid pathway, the aromatic amino acids are synthesized from:

aromatic amino acids

The shikimic acid pathway converts simple carbohydrate precursors derived from glycolysis and the pentose phosphate pathway to the _____.

shikimic acid pathway

The _____ converts simple carbohydrate precursors derived from glycolysis and the pentose phosphate pathway to the aromatic amino acids.

glyphosate
Roundup

The well-known, broad-spectrum herbicide _____ (available commercially as _____) kills plants by blocking a step in the shikimic acid pathway.

plants
fungi
bacteria
animals

The shikimic acid pathway is present in _____, _____, and _____ but is not found in _____.

shikimic acid

The _____ pathway is present in plants, fungi, and bacteria but is not found in animals.

phenylalanine, tyrosine, tryptophan

Animals have no way to synthesize the three aromatic amino acids—_____, _____, and _____—which are therefore essential nutrients in animal diets.

phenylpropanoid
100:70:7
Gymnosperm

The _____ units that make up lignin are not linked in a simple, repeating way. The lignin of beech contains units derived from coniferyl alcohol, sinapyl alcohol, and para-coumaryl alcohol in the approximate ratio _____ and is typical of angiosperm lignin. _____ lignin contains relatively fewer sinapyl alcohol units.

coniferyl alcohol
sinapyl alcohol
para-coumaryl alcohol
angiosperm

The phenylpropanoid units that make up lignin are not linked in a simple, repeating way. The lignin of beech contains units derived from _____, _____, and _____ in the approximate ratio 100:70:7 and is typical of _____ lignin. Gymnosperm lignin contains relatively fewer sinapyl alcohol units.

lignin
lignin
lignin

The phenylpropanoid units that make up _____ are not linked in a simple, repeating way. The _____ of beech contains units derived from coniferyl alcohol, sinapyl alcohol, and para-coumaryl alcohol in the approximate ratio 100:70:7 and is typical of angiosperm lignin. Gymnosperm _____ contains relatively fewer sinapyl alcohol units.

Mechanical damage, recognition of insect elicitors, induction of direct defenses, "the cry for help"

_____, _____, _____, _____, and _____ are some of the major events associated with induced defense responses.

induced defense
fatty

Mechanical damage, recognition of insect elicitors, induction of direct defenses, and "the cry for help"—the recruitment of parasites and predators of the attacking herbivore through the release of so-called volatile organic compounds (VOC)—are some of the major events associated with _____ responses. A central role in these processes is played by jasmonic acid (JA), a _____-acid-derived signaling compound common to most, if not all, plants.

-the recruitment of parasites and
predators of the attacking herbivore through the release of so-called volatile organic compounds (VOC)
-jasmonic acid (JA)

Mechanical damage, recognition of insect elicitors, induction of direct defenses, and "the cry for help"(____________) are some of the major events associated with induced defense responses. A central role in these processes is played by _____, a fatty-acid-derived signaling compound common to most, if not all, plants.

secondary metabolism

Plants make a variety of less widely distributed compounds such as morphine, caffeine, nicotine, menthol, and rubber. These compounds are the products of _____, which is the metabolism of chemicals that occurs irregularly or rarely among plants, and that have no known general metabolic role in plants.

required
metabolic

Secondary metabolites or secondary compounds are compounds that are not _____ for normal growth and development, and are not made through _____ pathways common to all plants.

alkaloids, terpenoids, and phenolics.

Secondary compounds are grouped into classes based on similar structures, biosynthetic pathways, or the kinds of plants that make them. The largest such classes are:

glycosides

Secondary compounds often occur in combination with one or more sugars. These combination molecules are known as _____. Usually the sugar is a glucose, galactose or rhamnose. But some plants have unique sugars.

ecological roles that govern interactions between plants and other organisms.

The most common roles for secondary compounds in plants are:

red
blue
pollinators
dispersers

Many secondary compounds are brightly colored pigments like anthocyanin that color flowers _____ and _____. These attract _____ and fruit and seed _____.

toxic

Nicotine and other _____ compounds may protect the plant from herbivores and microbes.

nitrogen

Alkaloids generally include alkaline substances that have _____ as part of a ring structure.

alkaloids

More than 6500 _____ are known and are the largest class of secondary compounds. They are very common in certain plant families.

Terpenoids

_____ are dimers and polymers of 5 carbon precursors called isoprene units (C5 H8).

Terpenoids
expensive

_____ often evaporate from plants and contribute to the haze we see on hot sunny days. They are _____ to make; they often take 2% of the carbon fixed in photosynthesis; carbon that could otherwise be used for sugars.

phenolics

Compounds that contain a fully unsaturated six carbon ring linked to an oxygen are called _____.

aspirin

Salicylic acid (basic part of _____) is a simple phenol.

vitamin C
rutin

Flavonoids are complex phenolics. They are often sold in health food stores as supplements to ____. The most commonly available flavonoid is _____ from buckwheat.

nutmeg

Myristicin is a more complex phenol that provides the flavor of _____.

Anthocyanins

_____ are a type of flavonoid that give flowers red and blue pigments.

polymers

Some phenolics form _____.

Mustard oil glycosides

_____ are nitrogen-sulfur containing compounds that occur in cabbage, broccoli, horseradish, watercress and other members of the mustard family (Brassicaceae). They give the group its characteristic taste and odor.

Cyanogenic glycosides

_____ occur in several families of plants, but are especially common in roses (Rosaceae) and peas (Fabaceae). They are sugar containing compounds that release cyanide gas when hydrolyzed.

Structural defense
Biochemical defense

Plants continuously defend themselves against attack from pathogens via:

macromolecule, a polymer consisting of
many long-chain fatty acids (16:0 and
18:1 fatty acids with OH)

Cutin

-cuticle
-resistance
-resistance

Cutin is a Component of _____ and
increase _____; however, its thickness is not always correlated with _____.

Particular secondary metabolites are often found in only one
plant species or related groups, whereas primary
metabolites are found throughout the plant kingdom.

secondary metabolites Differ from primary metabolites in distributions in that:

-Protect from against herbivores or pathogens
-Attractants for pollinators and seed-dispersing animals
-Agents of plant-plant competition and plant-microbe symbiosis secondary

secondary metabolites have three ecological functions:

-Nitrogen-containing secondary products.
-Phenolic compounds
-Terpenes

Three major groups of secondary metabolites:

-Largest class, diverse, generally
insoluble.
-derived from the union of fivecarbon
elements (C5 units)

Terpenes

-Toxins
-Play important defensive roles in the plant kingdom

Terpenes against herbivores

-Hydroxyl functional group on an aromatic ring
-Heterogeneous group of nearly 10,000 individual compounds:
some soluble, some insoluble, some polymer

Phenolic compounds

-Defense compounds against herbivores and pathogens
-Mechanical support
-Attracting pollinators
-Absorbing UV radiation
-Reducing the growth of nearby competing plants

Phenolic compounds have diverse functions:

phenolics
major
minor

Plant _____ are biosynthesized in
several different ways. The Shikimic acid pathway the _____ pathway. The Malonic acid pathway is the _____ pathway.

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