Lecture 4
mendel studied inheritance of 7 single genetic traits
Independent assortment: allele pairs separate independently during the formation of gametes. This
means that traits are transmitted to offspring independently of one another.
Has practical applications in assembling useful genes in modern crop varieties by breeding.
(agricultural genetics)
Prior to mendel's crops, people would just take the plants that were good in the crop. Post mendel,
breeders realized they can breed with phenotypes they want. Ex: Xa4/Xa4 = dominant risease
resistance, but sub 1/sub 1 flooding tolerance. The other plant has xa4/xa4 (no disease resistance)
and Sub1/Sub1 (flood resistance). You can cross them, some of the progeny will have both flood
and disease resistance.
How to guarantee whcih ones are homozygous for both traits, self them and select for the progeny
that show both genes. Keep selfing and selecting until you make the inbred line that is homozygous
for both of the wanted traits. Farmers who try the traditional stuff may get plants wt unwanted
traits.
This process lead to the Green revolution, when breeders started to apply Mendel's second law,
creating inbred lines from those hybrids. This is why wheat yield has increased so much since the
50s.
Irish potato famine was due in large part that only a certain genotype of potatoes was grown in
ireland, a genotype that had suscueptibility to a certain blight, they got this blight, and many died.
This happened on a smaller scale in the Southern Corn Leaf Blight. Currently, we are having the
Cavendish Banana blight (the bananas will die?!?!?!?!?)
Want of genetic resources...Svalbard seed vault (doomsday seed vault)
Svalbard Global Seed Vault Deep inside a mountain on a remote island in the
Svalbard archipelago, halfway between mainland Norway and the North Pole, lies the
Svalbard Global Seed Vault. It is a fail-safe, state-of-the-art seed storage facility, built
to stand the test of time – and of natural or manmade disasters. Reservoir of genetic
resources.
Permanent protection for the world’s food crops The purpose of the Vault is to store
duplicates (‘back ups’) of all see
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