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Gene*cs  in  Agriculture:  Crop  Breeding  

1.  Review  of  plant  reproduc*on  2.  Basic  gene*c  concepts  and  defini*ons  3.  PunneC  squares  4.  Plant  breeding:  goals  5.  Plant  breeding:  strategies  –  Ar*ficial  Selec*on  vs  Natural  Selec*on  –  Gene*c  transforma*on  –  Tradi*onal  breeding  vs.  gene*c  engineering  

Plant  reproduc*on  •  Review  parts  of  a  flower  •  Gametes  fuse  to  form  a  seed  •  Self-­‐pollina+ng  plants  –  pollen  from  anther  transferred  to  s*gma  on  same  flower  

•  Cross  pollina+ng  plants  –  pollen  transferred  to  s*gma  of  another  plant  

DNA,  Chromosomes,  and  Genes  •  Chromosomes  are  located  in  cell  nuclei  

–  Determine  inheritance  of  traits  –  Made  of  DNA  organized  into  genes  –  Contain  thousands  of  genes  

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DNA,  Chromosomes,  and  Genes  •  Genes  made  of  nucleo*des  (A,  C,  G,  T)  

–  Different  forms  of  a  single  gene  are  called  alleles    

•  3  nucleo*de  pairs  form  an  amino  acid  –  Amino  acids  code  for  traits  

Gene*cs:  Terms  •  Genotype  vs  phenotype  •  Homozygous  vs.  heterozygous    •  Dominant  recessive  vs.  co-­‐dominance  

Basic  Mendelian  gene*cs:    PunneC  squares  

What  happens  when  you  cross  a  homozygous  dominant  pea  with  a  

homozygous  recessive  pea?    

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Basic  Mendelian  gene*cs:    PunneC  squares  

Basic  Mendelian  gene*cs:    PunneC  squares  

What  happens  when  you  cross  a  heterozygous  dominant  pea  with  a  

homozygous  recessive  pea?    

Basic  Mendelian  gene*cs:    PunneC  squares  

10/20/15  

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Gene*cs  in  Agriculture:  Crop  Breeding  

1.  Basic  gene*c  concepts    2.  Mendelian  gene*cs:  PunneC  squares  3.  Plant  breeding:  goals  4.  Plant  breeding:  strategies  –  Ar*ficial  Selec*on  vs  Natural  Selec*on  –  Gene*c  transforma*on  –  Tradi*onal  breeding  vs.  gene*c  engineering  

Plant  Breeding:  Goals  

•  Increase  Yield    •  Quality  traits  – Disease/insect  resistance,  compe**veness,  and  drought  tolerance    

•  Persistence  – Factors  that  will  enhance  survivability  long  term  

Many  strategies  to  achieve  same  goal  

1.  Determine  source  of  varia*on  2.  Determine  parent  materials  3.  Combine  parents/gene*c  varia*ons  to  get  

desired  yield  •  Ar*ficial  Selec*on  vs  Natural  Selec*on  •  Gene*c  engineering  •  Tradi*onal  breeding  vs.  gene*c  

engineering  

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Many  strategies  achieve  same  goals  

1.  Determine  source  of  varia*on  2.  Determine  parent  materials  3.  Combine  parents/gene*c  varia*ons  to  get  

desired  yield  •  Ar*ficial  Selec*on  vs  Natural  Selec*on  •  Gene*c  engineering  •  Tradi*onal  breeding  vs.  gene*c  

engineering  

Crop  gene*cs:  How  traits  evolve  

Wild  mustard  can  evolve  several  different  traits  –  each  leading  to  a  different  crop!  

Ar*ficial  selec*on:    Breeding  for  new  traits    

•  Start:  Wild  mustard  •  Want:  Broccoli  

Wild  mustard  (Brassica  oleracea)  

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Ar*ficial  selec*on:    Breeding  for  new  traits    

•  Start:  Wild  mustard  •  Want:  Broccoli  

     How  do  we  get  broccoli  with  the  desired  traits?  

Wild  mustard  (Brassica  oleracea)  

Ar*ficial  selec*on:    Breeding  for  new  traits    

•  Breed  individuals  with  desired  phenotype  with  one  another  

Ar*ficial  selec*on:    Breeding  for  new  traits    

•  How  does  this  differ  from  natural  selec*on?  

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Fig.  22.8  in  Campbell  &  Reece  7th  ed.  (p.  445)  

Reproduc*on  in  a  maple  tree—  boxelder  (Acer  negundo)  

Natural  vs.  Ar*ficial  selec*on  •  Natural  selec5on  is  similar,  but  the  selec*ve  forces  come  from  the  surrounding  environment  – “Cause”  of  evolu*on  is  from  nature,  not  humans  

GMOs  vs.  tradi*onal  breeding    

VIDEO  INTRO    

Hybridiza*on—Corn  •  Breeding  self-­‐pollina*ng  corn  plants  for  several  genera*ons  produces  iden*cal  inbreds  

•  Crossing  two  inbred  plants  with  dis*nct  gene*c  traits  =>  hybrid  

•  Hybrid  vigor:  First  hybrid  (F1)  typically  has  traits  superior  to  those  of  either  inbred  parent  

Hybrid  corn  produc+on.  

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•  Uses  gene  transforma*on  to  transfer  genes  of  interest  – Genes  may  originate  from  wide  range  of  sources  – Transfer  occurs  via  bacterium  or  gene  gun  

Gene*cally  Modified  Plants  

Gene*cally  Modified  Plants:    Friends  or  Foes?  

Benefits  •  Crops’  resistance  to  pests  •  Herbicide  tolerance  •  Adapta*on  to  

environmental  stresses  •  Desirable  func*onal  

characteris*cs    •  Desirable  nutri*onal  

characteris*cs  

Concerns  •  Safety  •  Human  health  •  Outcrossing  with  weedy  

rela*ves  •  Unintended  effects  on  

nontarget  organisms  •  Resistant  pests  

Tradi*onal  Breeding  versus  Gene*c  Engineering  

Tradi+onal  Breeding  •  Takes  years  to  get  desired  varie*es  

•  Transfers  many  genes  •  Uses  only  genes  of  same  or  related  species  

•  Not  prohibited  

Gene+c  Engineering  •  Desired  varie*es  produced  quickly    

•  Transfers  genes  of  interest  •  Can  use  genes  from  any  species  

•  Prohibited  in  organic  agriculture