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Crop development Flashcards

feeding the world environmental stress and food production bioengineering healthier foods climate change and the biosphere biofuels

1
Q

does grain have a longer or shorter shelf life than fresh food

A

longer

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2
Q

what are the different types of malnutrition

A 
marasmus energy (lack of calories)
acute hunger 
kwashiorkor (lack of protein)
chronic hunger 
hidden hunger (mineral deficiencies)
UK hunger
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3
Q

what are the symptoms of hunger

A

fatigue
thirst
weight loss
vision changes

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4
Q

what are the causes of hunger

A

insufficient food, may be due to:

  • war
  • natural disasters
  • poverty
  • limited access
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5
Q

what are the 4 criteria for food production that need to be met to prevent hunger

A
  • sustainable
  • robust
  • affordable
  • accessible
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6
Q

in what 3 ways can we achieve food security

A
  • expand (more land surface)
  • intensify (more yield/land surface and higher nutritional value)
  • be smart (grow the right crop in the right place at the right time, optimise yield, manage distribution etc)
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7
Q

what are the major food crops

A

soybean, cassava, maize, sweet potato, tomato, wheat, barley, potato, rice, sugarcane

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8
Q

which 2 major food crops are commonly used for biofuels

A

sugarcane and maize

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9
Q

what type of angiosperm is wheat

A

monocot

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10
Q

why is wheat so popular

A
  • nutritional value
  • baking qualities
  • one of the only cereal crops to produce gluten
  • wheat genome has been sequenced
  • can be intensively farmed
  • grain easily harvested, transported and stored
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11
Q

what are the different ways that rice can be cultivated

A
  • traditional wet rice cultivation

- dry cultivation

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12
Q

what are the advantages of wet rice cultivation

A
  • Work intensive
  • Natural weed control
  • Natural fertilization
  • Symbiosis with nitrogen fixing cyanobacteria
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13
Q

what are the advantages of dry rice cultivation

A
  • easy sowing and harvest
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14
Q

what are the disadvantages of dry rice cultivation

A

needs herbicides and fertilizer

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15
Q

why is rice so popular

A
  • genome has been sequenced
  • nutritional
  • easy to grow
  • intensive farming
  • many different varieties
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16
Q

give some reasons why extending into new land for crop growth is difficult

A

the land we currently use is well suited for growing crops. to grow crops in other environments, we would need to develop different agricultural methods

  • in dry land we need to maintain water
  • we may need to grow different crops of GM crops that can cope with the environment
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17
Q

what is a disadvantage of allowing consuming meet as opposed to crops

A
  • cattle graze on fields so although we gain energy from eating beef, a lot of the energy is still lost in the food chain
  • cattle produce greenhouse gases
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18
Q

how may we maximise the land available for food crops

A

we could grow non food crops e.g. for biofuel production, in marginal land or oceans

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19
Q

which type of grass has a large biomass

A

elephant grass

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20
Q

what type of grass grows on very dry land

A

switch grass

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21
Q

name 2 plants that grow in very saline conditions and suggest where they could be grown and what it could be used for

A

halophytes - green algae and samphire (very oily seeds)
can be grown in the sea
can be used for biofuels (projects are ongoing)

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22
Q

what are the advantages of using food products like maize or sugarcane for biofuels as oppose to using non-food crops

A

the food crops produce a lot more biomass than non food crops when they are grown on good land

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23
Q

give some examples of what is meant by marginal land

A
  • hot
  • dry
  • saline
  • poor nutrient
  • polluted lands e.g. heavy metals
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24
Q

how can we get around the issue of growing plants on marginal land

A

either find or manipulate plants that can grow in these conditions or find or manipulate plants that can grow and improve the environment to make a more suitable environment for other crops

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25
Q

how could we generate salt tolerant plants

A
  • overexpression on tonoplast Na/H antiporter gene NHX1
    e. g. tomato plant grown in NaCl
  • NHX1 overexpressors were able to grow well but the wild type could not
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26
Q

how do plants protect their tissues from salt

A

they have developed a thick, waxy coating that prevents water loss and many of the plants have pores that deposit salts outside
the salt does no move into the fruits and instead just accumulates in the leaves

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27
Q

which of the major crops did not originate in tropical/warm climates

A

potatoes

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28
Q

give two examples of limiting factors of wheat cultivation

A

the number of frost-free days

the amount of rainfall

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29
Q

name a plant that is frost tolerant

A

Canola (rapeseed)

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30
Q

what are CBFs

A

cold inducible transcription factors which control the expression of genes for protective responses

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31
Q

what do CBF 1 mutants show

A

they overexpress transcription factors and show enhanced frost and drought tolerance

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32
Q

what is the formula for yield gap

A

yield potential - actual yield

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33
Q

give examples of factors that cause yield gap

A

both biotic and abiotic factors, however abiotic factors are much more damaging
biotic factors - disease, pathogens, pests, nematodes
abiotic factors - temperature water availability, nutrient availability

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34
Q

how may we decrease the yield gap

A

by increasing tolerance to abiotic stress

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35
Q

what occurs when plants experience drought and heat

A

they experience water deficit
- they produce the stress hormone ABA which is perceived by calcium, the second messenger, which initiates the protective response, the closing of stomatal pores

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36
Q

what is the effect of closing stomatal pores in response to heat and drought

A
  • reduced water loss
  • increased temperature due to less evaporative heat loss by transpiration
  • reduced CO2 uptake for photosynthesis
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37
Q

which organs of the plant are particularly sensitive to high temperature

A

reproductive organs

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38
Q

what are the advantages and disadvantages of not closing stomata during drought

A

advantages: the plant keeps cool as it undergoes transpiration
disadvantages: the plant loses water and dries out

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39
Q

what are the advantages and disadvantages of closing stomata during drought

A

advantages: the plant retain their water
disadvantages: the plants generally die of heat stress

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40
Q

what are the 3 basic steps in any plant response to warning signals

A
  1. growth arrest
  2. developmental delay
  3. survival
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41
Q

how can we make plants less responsive to environmental stimulus

A

we can disrupt signalling pathways

the plant would have less protection, but it would grow and develop more.

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42
Q

describe rain fed drought plants

A
  • they have better yield under mild drought stress
  • they cannot survive long term stress
  • they require management (some irrigation as and when necessary)
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43
Q

describe irrigated drought plants

A
  • water is supplied

- they need less water - they have high water use efficiency

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44
Q

describe normal rain fed plants

A
  • less yield under mild drought stress (natural response is to stop growing)
  • they will survive and reproduce seed under long term stress
  • they do not need management
45
Q

describe normal irrigated plants

A
  • they need more water

- they have low water use efficiency

46
Q

what is the stress recovery mechanism of resurrection plants

A
  • resurrection plants accumulate high levels of trehalose as a compatible solute for osmoregulation
47
Q

what is trehalose and what is its function in plants

A

sugar that attracts water into the plant and lowers freezing point - less frost
it is a compatible osmolyte

48
Q

what is reverse genetics

A

identify drought tolerance genes and alter expression levels in plants

49
Q

what is forward genetics

A

classical approach – select for drought tolerance based on phenotype

50
Q

when using the forward genetic technique what is important to remember

A

need to increase gene pool; bring old landraces (a cultivar of the breed improved by agriculture) back into play
to prevent inbreeding

51
Q

give a list of how or crops have evolved (both natural responses and synthetic alterations)

A
  • Originally large genetic (allelic) variation within a species  many landraces
  • Selection by climate
  • Selection by farmers
  • Loss of heterogeneity (alleles)
  • Inbred lines now dominate
  • many plants have just been crossed for yield so robustness, grain quality etc has been sacrificed and lost
52
Q

wild species –> landraces –> cultivars

shows a increase/decrease in allelic diversity

A

decrease - crops have been selected for specific traits over time and so genetic variation has been lost

53
Q

what are the essential elemental inputs required for crop production

A

nitrogen, phosphorus, potassium

54
Q

what is the advantage of dwarfism in plants

A
  • Plants were growing too tall and falling over (lodging) – making harvesting impossible
  • The large plants were mainly straw instead of grain, so all the nutritional ammonia accumulated in the straw which wasn’t consumed
  • New dwarf varieties have a higher grain to straw ratio and so, reduced losses from lodging
55
Q

list the 3 types of plant pathogens

A

fungi
bacteria
viruses

56
Q

list 5 plant pests

A 
lepidopteran larvae (caterpillars)
sap-sucking bugs 
nematodes 
beetles 
locusts
57
Q

what is the average percentage loss of yield due to abiotic factors

A

40%

58
Q

what is black leg potato disease

A
  • the disease is caused by the bacterium Pectbacterium carotovora
  • can result in wilting, chlorosis of leaves, necrosis of several tissues, a decline in yield, and death of the potato plant.
59
Q

what is potato soft rot

A
  • caused by the bacterium Pectobacterium atrosepticum

- Infection causes losses, particularly in storage

60
Q

what are plant viruses usually transmitted by

A

vectors such as aphids, leafhoppers, whiteflies and nematodes

61
Q

over 50% of emerging plant diseases are …………. in origin

A

viral

62
Q

what is Phytophthora infestans

A

a fungus that causes late potato blight

63
Q

what happens to plants with late potato blight

A
  • infects the potato foliage and its tubers
  • In moist cool conditions the entire foliage of a crop can be destroyed within 2-3 weeks
  • lesions caused by the pathogen can occur on leaves or stems.
64
Q

what defence mechanisms do plants use to protect themselves from pathogens

A
  • plant may possess preformed structural barriers or toxic substances that confine infection to particular pathogen species
  • plants may be able recognize the attacking pathogen and activate defence mechanisms that prevent the pathogen from spreading or localize the infection
65
Q

what kind of immunity do plants have

A

only inherited immunity - innate immunity

66
Q

what are the 2 main branches of plant immune systems

A

basal and gene-for-gene

67
Q

what is basal immunity

A

Plant cells carry proteins on the outside of the plasma membrane that can recognize macromolecules (such as proteins or polysaccharides) that are associated with pathogens. These contain slowly evolving Pathogen Associated Molecular Patterns (PAMPS) such as flagellin, cell wall glycans, etc

68
Q

what is gene-for-gene immunity

A

Acts largely within the cell using proteins encoded by Resistance Genes (R-genes). These recognize pathogen-specific effector molecules from diverse kingdoms and activate defence responses

69
Q

give examples of PAMPs

A 
bacteria:
- flagella 
- LPS
- elongation factor Tu 
fungi:
- ergosterol 
- chitin
- beta-glucans
70
Q

what is the gene-for-gene hypothesis

A
  • for resistance to occur, complementary pairs of dominant genes must be present in the host and pathogen
  • these genes are referred to as Resistance (host) and Avirulence (pathogen). Altering either of these genes leads to susceptibility.
71
Q

what are avirulence genes

A

genes that encode proteins that are essential for the pathogen to invade and grow in the plant host

72
Q

bacterial and fungal pathogens inject proteins into the cells of their host. what are these proteins called

A
  • effectors – they control host defence responses and are essential for infection
  • the Resistance genes bred into crops usually recognize one or more of these effectors.
73
Q

what is the type 3 secretion system

A
  • it is a protein appendage found in several Gram-negative bacteria
  • it is used as a sensory probe to detect the presence of eukaryotic organisms and secrete proteins (encoded by avirulence genes) that help the bacteria infect them
  • The secreted effector proteins are secreted directly from the bacterial cell into the eukaryotic (host) cell, where they exert a number of effects that help the pathogen to survive and to escape an immune response
74
Q

what is the response to infection in resistant plants

A

localised responses including programmed cell death

75
Q

what is the systematic acquired resistance response most strongly elicited by

A

gene-for-gene responses

  • Salicylic acid (SA) acts as a signalling molecule in SAR.
  • plants with acquired resistance show reduced susceptibility to a subsequent infection by either virulent or avirulent pathogens.
76
Q

describe the synthesis of pathogen related proteins

A
  • include proteins with likely anti-pathogen properties e.g. chitinases (insects), beta1-3 glucanases (bacterial and fungal cell walls).
    1. Synthesis of cell wall structural proteins. Function to strengthen cell walls
    2. Synthesis of specific anti-fungal, -bacterial or -viral compounds.
77
Q

what are boom years

A
  • years in which there was effective disease control, use of specific R genes increases
78
Q

what are bust years

A
  • years in which disease control fails, use of specific R genes decreases
79
Q

how do we convert from bust years to boom years

A
  • plant breeders search for new R gene

- replacement R gene introduced

80
Q

how are boom years converted to bust years

A
  • selection pressure on the pathogen population steadily rises (arms race)
  • prevalence of novel races in which the corresponding avirulence gene is lost or mutates to a non functioning allele increases
81
Q

The P. infestans genome encodes more than ………. effector proteins

A

400 - some of these are targets for resistance genes

82
Q

because many of the effector proteins act redundantly, the pathogen can easily evolve to lose or change the ………….. gene, allowing it to overcome resistance by “evading” the R-gene protein.

A

Avirulence

83
Q

how can we engineer plants for disease resistance

A
  • Conventional Resistance - the use of genetic manipulation methods to introduce existing Resistance genes into cultivars or species in which they do not naturally occur
  • Novel Resistance - the use of genetic manipulation methods to introduce genes that function to limit pathogen spread by mechanisms other than via conventional resistance.
84
Q

what are the non conventional approaches of inducing resistance in plants (not based on R genes)

A
  • Pathogen derived resistance to a virus: Constitutive expression of the major structural protein protects against infection
85
Q

what is Bt

A
  • Bacillus thuringiensis - a gram-negative bacterium which produces proteins called Bt toxins which show species specific toxicity to larvae
  • the proteins are digested by proteolytic enzymes in the gut to form polypeptides which are bound to receptors in the brush border membranes.
  • the toxin irreversibly inserts into the membrane, forming pore
  • epithelial cell lysis leads to gut paralysis and death `
86
Q

how can we make transgenic plants expressing Bt

A

Genes encoding the bt toxin can be inserted into plants using Agrobacterium or Biolistics. Expression of the appropriate protein gives plants that are toxic to the target larvae. The high specificity of bt toxin means that the transgenic plants show negligible toxicity to beneficial insects such as bees

87
Q

Brassicaceae and other oil producing plants naturally contain large amounts of what

A

very long chain monosaturated fatty acids (20-24 carbon chains)

88
Q

which fatty acid has been shown to cause heart disease

A

erucic acid

89
Q

what s different about Brassicaceae compared to other oil producing crops

A

Brassicas are tolerant of low temperatures, and therefore well suited to cooler temperate regions

90
Q

in 1950 plant breeders began a programme to isolate Rapeseed lines with low erucic acid levels. what is the new strain with low erucic acid levels called

A

canola

91
Q

how were the levels of erucic acid reduced

A

by mutagenesis and conventional breeding

92
Q

which fatty acids are healthiest

A

monosaturated (18:1) fatty acids are better than polyunsaturated (18:2) or saturated (18:0) fatty acids

93
Q

what is the effect of knocking out genes from oil seed crops that code for lipid desaturases

A

there is an increase in monounsaturated fatty acids and a decrease in saturated fatty acids

94
Q

what gives margarine a semi solid consistency

A

it contains 30/40% unsaturated fats

95
Q

what is the difference between omega 3 and omega 6 fatty acids

A

omega 3 double bond between 3rd and 4th carbon

omega 6 double bond between carbon 6 and 7

96
Q

what are the health implications of omega 3 and omega 6 fatty acids

A
  • Omega 3 fatty acids are found in fish, olive oil and nuts. omega 3 fatty acids reduce inflammation and stimulate hair and skin growth - they have low intake in the population
  • omega 6 fatty acids are commonly found in the diet in meats and fast food omega 6 fatty acids lessen the risks of diabetic neuropathy, rheumatoid arthritis - too much can increase inflammation.
97
Q

where are omega 3 plant synthesised

A

only in plants

98
Q

which cold water plant produces high omega 6/omega 3 fatty acid ratio

A

cold water algae

99
Q

what is currently the principle source of omega 3 fatty acids

A

fish oils - we could use modified plant oils to ease the pressure on fish stocks

100
Q

what is the precursor for fatty acid biosynthesis

A

acetyl coA - plants contain a cytosolic and plastid enzyme (ACCase) for producing acetly-CoA

101
Q

how do we increase lipid accumulation in seeds

A

activity of both the plastid and cytosolic enzymes is highly regulated in their respective compartments - over expression of either gene does not result in higher lipid yields. Expression of a cytosolic ACCase cDNA in Brassica plastids results in an increase in oil content of seeds

102
Q

what is the reason that many infants lose their sight

A

lack of vitamin A due to their diet being mainly rice

rice originally contains vitamin a but it is removed to prevent rot in storage

103
Q

what can we use to make biodegradable plastics

A

plants

104
Q

what was the result of Gene Editing to delete the genes encoding Fatty Acid Desaturate 2

A

greatly increased levels of the monounsaturated FA oleic acid

105
Q

give examples of plant derived proteins that are available commercially now

A 
trypsin 
beta-glucuronidase
lysozyme 
interferons 
antibodies 
anti HIV drugs
106
Q

describe antibody production in plants

A
  • they are made in the B lymphocytes
  • the variable part of the antibody is generated by gene rearrangements during B lymphocyte development
  • B lymphocytes from mice can be immortalized, generating monoclonal antibodies
  • gens from suitable monoclonal antibodies can be clone and expressed in plants
107
Q

what is the zmapp treatment for ebola

A
  • mixture of three monoclonal antibodies against the virus
  • humanized antibodies were generated as mouse monoclonals. Genes for the light and heavy chains were cloned and expressed in a relative of tobacco then used for treatment
108
Q

what can products of GM tobacco plants fight against

A

drug resistant malaria

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