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APS206: Biotechnology & Food Security > Lecture 5: Traditional crop breeding > Flashcards

Lecture 5: Traditional crop breeding Flashcards

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1
Q

the varieties of plants we real on are of fundamental importance for

A

human survival

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2
Q

how are seeds stored around the world?

A

large seed banks

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3
Q

was domestication of plants achieved once?

A

NO, it was achieved a number of times across the world independently

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4
Q

how do we date when domestication has occurred? & e.g.

A
  • Archeological records

- cucurburbita pepo peduncle 14C date of 7340 +/- 60 years BP

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5
Q

Characteristics of wild plant populations:

A
  • species are genetically diverse
  • within a local region, genes which confer a selective advantage will be predominant
  • ECOTYPE
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6
Q

sub-population of wild plants which share local region, genes which confer a selective advantage reulsting in predominance is known as an

A

ECOTYPE

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7
Q

Characteristics of wild plant populations: a balance is set up between:

A
  • adaptations to the local environment which tend to REDUCE local genetic diversity
  • A requirement to respond to altering conditions which INCREASES genetic diversity
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8
Q

the traits we want in crops are often not those that have evolved naturally so humans

A

Selected traits

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9
Q

Traits selected for by humans for domesticated plants:

A
  • High carbohydrate (or oil) - STAPLES
  • Possess traits that are useful in an agricultural environment (seed retention, size etc)
  • Therefore there were multiple domestication events occurred throughout human history
  • creating a more reliable food supply
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10
Q

seed retention allows you to

A

harvest your crop all at the same time

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11
Q

Why were crops domesticated?

A
  • MORE RELIABLE FOOD SUPPLY
  • provides for a more predictable food supply
  • -location
  • -uniformity
  • Gives greater yields since conditions can be controlled
  • -irrigation
  • -fertilisation
  • -protection
  • Select FOR beneficial traits, AGAINST undesirable traits, FOR new traits
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12
Q

What were the consequences of domestication of crops?

A

-yield increase
-population increases
-people stop moving , they live in settlement (villages, towns, cities)
-people have more time (science, art, communication)
Higher densities = more disease
-We want what others have = WAR

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13
Q

what do Cauliflower, Kale, Broccoli, Brussel sprouts, Kohl rabi, Cabbage have in common?

A

SAME SPECIES

-we’ve selected different traits

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14
Q

The agricultural environment is different to the wild environment, meaning the selection pressures are

A

also different

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15
Q

selection of a wild population in an agricultural environment generates

A

LANDRACES

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16
Q

continued selection from one individual plant will give rise to an

A

INBRED CULTIVAR.

Breeding introduces new genes into these cultivars

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17
Q

cultivation of potatoes was introduced to Europe in the

A

mid 16th century

18
Q

potatoes originated in the tropical highlands of

A

South America

19
Q

original varieties of potato compared to European varieties

A

ORIGINAL VARIETIES:
-diploid
-low yield
-flower when days are short (flowers in Autumn in Europe > no tubers)
-High alkaloid content (good for pest resistance but toxic)
EUROPEAN VARIETIES:
-tetraploid
-high yield
-flower when days are long(flowers in Summer in Europe)
-Low alkaloid content
-not toxic

20
Q

Wild beet is:

A

leafy & is thought to be Beta maritima

21
Q

Wild beet was domesticated in

A

prehistoric times

  • leafy plants= swiss chard
  • Root crop = beetroot
22
Q

by 18th century sugar beet had been developed with

A

6% sucrose content

23
Q

Beet & Napoleon & Achard

A
  • in 1799 Achard developed a process for extraction sugar from sugar beet
  • in 1811 Napoleon decreed that beet should be grown as an alternative to cane sugar (in response to British naval blockade)
24
Q

sucrose content in beet over time:

A
  • sucrose content rose steadily as a result of selection
  • limit eventually reached
  • genetic diversity exhausted
  • physical max reached
  • root sizes still increased further
25
Q

where is sugar from today?!

A

still a division between cane (Tate & Lyle) and beet (British Sugar) manufacturers

26
Q

illinois long-term selection experiment, maize tested for oil & protein content OUTLINE

A

-started in 1896
-163 ears of the maize variety Burr’s White (an open-pollinated variety) were tested for oil and protein content
-a subset of the grains were grown & re-selected every year
(• Illinois High Oil (IHO)
• Illinois Low Oil (ILO)
• Illinois High Protein (IHP)
• Illinois Low Protein (ILP))
-At various times the selection was changed e.g high protein varieties were selected for high oil etc.

27
Q

illinois long-term selection experiment, maize tested for oil & protein content RESULTS - Protein

A
  • Upper biological limit not attained, lower biological limit reached at certain level
  • Can continue adding proteins but basic level required for cell to survive
28
Q

illinois long-term selection experiment, maize tested for oil & protein content RESULTS - OIL

A
  • lower biological limit reaches 0
  • those which are switched, first selected for low then changed to high, never read high again as some genes are lost by selecting for low originally
29
Q

potato eelworm:

A
  • nematode pest
  • major limitation to production in Europe in 1930’s
  • 1200 different potato accession screened, 6 were found to be resistant
  • -resistance due to the H1 gene
  • -interferes with the reproductive lifecycle of pest. Eggs hatch but do not develop
  • Nematode population also diverse, H1 gene only conferred resistance to sub-population
  • other genes were found which gave resistance to other nematode races
30
Q

How do we breed? (i.e. carrots)
commercial= good yield, good colour, susceptible
old = poor yield, poor colour, resistant

A

1) commercial variety & old variety CROSS
2) lots of outcomes in F1, repeated rounds of crossing and selection to achieve NEW commercial variety (good yield, colour + resistant)

31
Q

hybrid vigour =

A

HETEROSIS
a hybrid between two genetically different parents which can give better yields than either parent.
-BECAUSE the plant is heterozygous
-an inbred line will be homozygous i.e. true breeding. Both copies of chromosome will be identical

32
Q

crossing two different inbred lines gives rise to a

A

hybrid (F1)

33
Q

hybrid vigour in Maize

A
  • need to control pollination (to avoid self-pollination)
  • plant male & females in alternating rows
  • make females produce no pollen
  • this was done using a natural mutation (but also made pants susceptible to Southern Corn Blight, unintended consequence)
  • with maize u can also hand emasculate (cut the hassles off)
34
Q

F1 hybrids in Maize hybrid vigour development:

A
  • Naturally occurring male sterility allowed F1 hybrids to be generated on a commercial scale.
  • The mutation which lead to sterility also lead to susceptibility to Southern Corn Blight.
  • Crop losses were devastating.
35
Q

modern agriculture uses monocultures of genetically uniform plants as the result in _ but ___

A

high yield but disease outbreaks can be devastating

36
Q

IRRI was established in

A

1960 and released various rice lines

37
Q

lodging in cereal =

A

more nitrogen results in elongation of stem which then collapse

38
Q

____ genes resulted in the Green Revolution in agriculture

A

Dwarfing

39
Q

The introduction of a dwarfing gene into rice reduced lodging problems:

A

• Yields of 11 tonnes/hectare with 150 kg N/hectare applied were achieved.
• The line was called IR8 and its cultivation spread rapidly.
• It is estimated that it replaced up to 5000 landraces and cultivars of rice in India alone.
-However, the IR8 line was susceptible to many pathogens and an intensive breeding programme followed.
• The IRRI collected 100,000 lines of rice for use in breeding programmes.

40
Q

phonemics:

A

measuring the phenotype of a plant using automation

APS206: Biotechnology & Food Security (19 decks)

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