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From out of old fields comes all this new corn:

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Title: From out of old fields comes all this new corn:


1
1
Early Knowledge of Pollination
  • Smyrna Fig and Date Palm, both dioecious
  • Male and female trees grown separately, 2400
    b.c.e.
  • Near Eastern Deity presided over pollination,
    1000 b.c.e.
  • Separation of sexes discussed by Aristotle
  • Sexual process in plants understood only in very
    limited fashion despite manipulation in
    agriculture
  • Specific nature of sexual organs and elements
    described in 17th century

2
2
Sexual Reproduction in Plants
  • Nehemiah Grew described anthers in 1676
  • Camerarius described sexual process, 1694
  • Kolreuter studied the pollination process,
    1761-1766
  • Described diversity of pollen grains, studied
    pollen germination
  • Thought he had identified half-hybrids or
    plants from two different pollen sources
  • Similar to Aristotles belief about fertilization
    as a mixing of fluids between the parents

3
Early Research on Hybridization
3
  • Kolreuter (1776) interspecific crosses hybrid
    vigor ...never has anyone seen more magnificient
    tobacco plants than these were.
  • Knight (1799) ...nature intended that a sexual
    intercourse should take place between neighboring
    plants of the same species.
  • Wiegmann (1828) heterosis in crucifers
  • Gartner (1849), Focke (1881) crossing
  • Naudin (1865) heterosis, segregation
  • Mendel (1865) heterosis

Cotton Mather
4
4
19th Century Research
  • Darwin discussed the sexual process in plants and
    animals simultaneously, a new concept for the
    time
  • Gartner crossed more than 700 species (1839-1849)
  • Demonstrated increased variability in the F2 over
    F1
  • Studied effects of backcrossing
  • Herbert showed wide crosses often sterile,
    crosses between varieties often fertile
    (1819-1847)
  • Mendel, 1865, fundamental laws of heredity, pea
    crosses

5
5
Gregor Mendel
  • Irony of celibate monk who discovers laws of
    heredity
  • Orel (1996) definitive work on life of Mendel
  • Mendel had broad interests in natural science
  • Collected climatological data and other natural
    data
  • Had clear interest in fruit and vegetable
    breeding
  • Life as a scientist protected in monastery
  • Pea experiments outlined fundamental laws of
    heredity
  • 1865 paper dormant for 35 years, rediscovered
    1900

6
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7
6
At the Beginning of the 20th Century
  • Pedigree records were kept by breeders
  • Vilmorin introduced statistical valuation of
    lineages in these pedigrees, thereby bringing in
    the era of the progeny test
  • The progeny test introduces predictability
  • Because individuals are valued based on the
    quality of their progeny
  • Led to data-driven decisions in plant breeding
  • Although unknown, genes regulated inheritance
    from parent to progeny, thereby making it
    predictable

8
7
Parents
1
2
3
4
Progeny Testing
1x2
75 Keep
2x3
35 Drop
1x4
90 Keep
9
8
Johannsens Pure Line Theory
  • Grouped Princess seeds based on weight into 10
    centigram classes self-pollinated them
  • Heavier seeds gave rise to heavier progenies
  • Established 19 lines with different seed weight
  • Each line self-pollinated for 6 generations
  • Lines showed no change in mean seed weight

10
9
Source
Johannsens Experiment
Select Within
Light
Heavy
Light
Heavy
Light
Heavy
11
10
Importance of Johannsen
  • Statistical valuation of seed weight both within
    lines and among lines
  • Lack of statistical significance for seed weight
    within lines
  • Correlation between parent and offspring
  • Suggested genetic control of seed weight
  • Suggested genotype remains constant each gen.
  • Original population must have been a mixture of
    pure lines selection ineffective in a pure line
  • Relationship between genotype and phenotype

12
11
Continuous and Discontinuous
  • Mendel found an explanation for inheritance of
    discontinuous variation
  • Johannsen found explanation for manipulation of
    continuous variation
  • However, he did not find any Mendelian factors
  • This was left to Nilsson-Ehle (1909) and East
    (1916), who demonstrated that continuous
    variation was due to multiple, Mendelian factors

13
12
Importance of Nilsson-Ehle
  • Statistical valuation of segregating progeny from
    colored by non-colored strains of wheat
  • Found that with 3 loci segregating, the F2
    distribution approached a normal curve
  • F2 individuals with 0,1,2,3,4,5,6 red alleles
    showed ratio of 1615201561
  • Led to multiple factor hypothesis

14
13
Importance of East
  • Statistical valuation of segregating progeny from
    long x short corolla length cross in Nicotiana
  • Corolla length a quantitative trait, but
    variability in F2 could be explained by 1, 2, 3,
    and 4 segregating genes
  • Suggested quantitative traits were really
    multiple Mendelian factors segregating in the F2
    generation

15
14
The Poor Soil of New England
16
15
Justus von Liebig (1803-1873) and Agricultural
Chemistry
  • Great tradition of European research in soil
    fertility
  • Liebig trained Samuel Johnson
  • Samuel Johnson began CAES, 1875
  • First of its kind in U.S.
  • Promises made...

www.uni-giessen.de/gi04/justus.html
17
16
Edward East and Inbreeding
  • Edward East, chemistry student, was assistant to
    Hopkins in 1900
  • Hopkins was breeding for oil and protein
  • East was influenced by Hottes and the new
    Mendelian heredity
  • In 1904, East noticed that all selected ears that
    were high in protein traced back to a single ear
    of the original population!

East and Jones, Genetic Studies on the Protein
Content of Maize, Genetics
18
17
Chemistry and Biology
  • E.H. Jenkins, chemist, hires East as breeder at
    CAES in 1905
  • Goal was to use breeding to
  • improve New England crops
  • East brings Illinois strains
  • Works on corn, tobacco
  • Begins era of applied genetics

E.M. East
Crabb, Hybrid Corn Makers, Fitzgerald, Business
of Breeding
19
18
Harvards Ag School
  • Busseys will of 1835 a school
  • for practical agriculture and horticulture
  • Anticipates Morrill Act by 27 years
  • Bussey Institution in Jamaica Plain begins in
    1872

Benjamin Bussey Merchant, Farmer,
Philanthropist
Wheeler, Bussey Institution, In Morison, The
Development of Harvard University
20
19
The Bussey Does Not Succeed
  • Rental properties to fund school
  • Fire of 1872 reduces funds
  • Students forced to grow vegetables and cut wood
  • Fewer than 12 students each year, few degrees
    granted

The Bussey Institution, 1872 Jamaica Plain, MA
Wheeler, Bussey Institution, In Morison, The
Development of Harvard University
21
20
Graduate School of Applied Biology
  • Reorganized in 1908 as a graduate school
  • Tackled the new frontier of genetics
  • Castle hired in mammalian genetics, East in plant
    genetics

W.M. Wheeler, Dean
Wheeler, Bussey Institution, In Morison, The
Development of Harvard University
22
21
44 Ph.D.s Granted, 1908-1936
  • Mammalian Genetics
  • Detlefsen, Little, Wright, Dunn, Reed
  • Plant Genetics
  • Emerson, Jones, Hayes, Anderson, Sax, Brink,
    Mangelsdorf, Smith, Sears
  • 14 Members of National Academy of Sciences
  • 1 Nobel Laureate

Weir, 1997 Wheeler, Bussey Institution, In
Morison, The Development of Harvard University
23
22
East
Brink Gaines Jones Hayes Emerson Mangelsdorf
Stadler Sax White Sears
Munger
Anderson
McClintock Burnham Lindstrom Beadle Sprague Rhoade
s
Immer Murphy Smith
Smith
Wilkes Laughnan
Wolff Swanson Rick Stebbins
Bringhurst
Srb
Hallauer
Gabelman
Allard Peloquin Nilan Neal
Harlan Garber Khush
Tanksley
Jain Kahler
Merz Young
Patterson Weber Schwartz
Russell Phillips
Love
Cornell California-Davis California-Berkeley Wisco
nsin Minnesota Iowa Missouri Illinois
Brown Duvick
Andrew
Freeling
Galinat
24
23
The Birth of U.S. Plant Genetics
  • Easts 1st student is R.A. Emerson
  • Studies limits of mass selection
  • Studies inbreeding
  • A new understanding of quantitative genetics
    emerges
  • Plant breeding has a firmer scientific foundation

R.A. Emerson
25
24
26
25
Heterosis in Animals The Mule as a Case Study
  • Donkey x horse cross mule
  • Heterosis for size, endurance
  • Sumerians, 3000 B.C.E.
  • Donkey x onager crosses
  • Zebra x donkey mules

27
26
Exploitation of Heterosis by Native Americans?

...The Indians in the region of
Quezaltenango...and the Hopi Indians...make a
regular practice of placing seeds of more than
one local variety in each hill, with the idea
that larger yields can be obtained in this
wayCollins, 1909
  • DNA from 700 yr. old Anasazi corn cobs
  • Identical RFLP patterns for each sample
  • Multiple fragments detected
  • Suggestive of heterozygosity Helentjaris, 1988

28
The Debt to Darwin
27
  • Nature thus tells us, in the most emphatic
    manner, that she abhors perpetual
    self-fertilization
  • On the Various Contrivances by which British and
    Foreign Orchids are Fertilised by Insects, and on
    the Good Effects of Intercrossing. (Darwin, 1862)

29
28
Long After the Galapagos...

I often asked myself how these many peculiar
animals and plants had been produced the
simplest answer seemed to be that the inhabitants
of the several islands had descended from each
other, undergoing modification in the course of
their descent and that all the inhabitants of
the archipelago had descended from those of the
nearest land, namely America....But it long
remained to me an inexplicable problem how the
necessary degree of modification could have been
effected, and it would have thus remained for
ever, had I not studied domestic production, and
thus acquired a just idea of the power of
Selection.
30
29
The Fanciers
  • Sir John Sebright
  • Pamphlet on selection
  • Nature infinitely more sagacious than man
  • These enthusiasts could judge to 1/16th of an
    inchand these differences formed the raw
    material to be accentuated through selective
    breeding
  • the most beautiful part of my theory

31
Principles of Natural Selection
30

Fecundity no district, no station, not even
the whole surface of the land or the whole ocean,
would hold the progeny of a single pair after a
certain number of generations. The inevitable
result is an ever-recurrent Struggle for
Existence.
Heritable Variation Differential Reproduction
and Survival Identical to mechanism of genetic
change in plant breeding populations with the
exception of human goal-directedness
32
Charles Darwin, Inbreeding, and Hybrid Corn
31
  • Darwin makes 37 different crosses
  • Observes increased height in 24 crosses
  • Observed decreased height in selfs
  • Shows that mechanisms exist to avoid inbreeding
  • Shows inbreeding may be a disadvantage
  • Shows no permanent injury through inbreeding
  • Shows effects reversed in progeny of first
    cross-pollinated generation
  • Inspiration of Asa Gray

33
32
England Boston Michigan Illinois Illinois
Illinois, CT Connecticut
1859 1860s 1880s 1890s 1890s 1900 1918
Natural Selection
34
A Culture of Inbreeding
33
  • Beal stressed pollination control
  • Trained Davenport and Holden
  • Early heterosis concept was only to prevent
    selfing
  • Deleterious, not advantageous, effects duly noted

35
Inbreeding at the University of Illinois, ca. 1900
34
  • Dean Eugene Davenport had worked with Beal at
    Michigan
  • Appointed Perry Holden (1896) and Archibald
    Shamel (1898)
  • Influenced by Beals work (pollination control)
    on inbreeding
  • Appointed Edward East (1900) and H.H. Love (1904)
  • Hottes returns from study Correns, De Vries, von
    Tschermak
  • Rediscovery of Mendels laws
  • Influences E.M. East to consider line uniformity

36
35
The Decline of Inbreeding Research

...We know what inbreeding does and I do not
propose to spend peoples money to learn how to
reduce corn yields. -Hopkins to East, as
told in Cannons Farm Quarterly Great Men of
Modern Agriculture cited in Fitzgerald
37
Composition of a Field of MaizeG.H. Shull, 1908
36
  • A variety is a complex mixture of hybrids
  • Each plant is of a different biotype (genotype)
    isolated by inbreeding
  • Reduction in vigor and variability due to
    segregation into homozygous types
  • F1 yield from line crosses exceeded the parental
    varieties from which lines came

38
37
The Centrality of Maize in Hybrid
DevelopmentSimmonds, 1979
  • Historical accident
  • hybrid method came at a time when new methods
    were needed
  • Economic weight
  • corn quickly becoming important US crop
  • Biological accident
  • simple emasculation technique

39
38
Hybrids Other Benefits
  • Overlooked benefit of uniformity
  • Coincidence of mechanical harvesting (1920s)
  • Consumer appeal
  • Lodging and disease resistance
  • Drought tolerance during droughts of 1934, 1936
  • Maturity, quality, storage duration

40
39
Hybrids and Private Enterprise
  • Shull expresses F1 non-renewability in 1908
  • East and Jones (1919) ...correspondingly less
    incentive for the production of improved
    types...
  • Lewontin OP improvement overlooked
  • Berlan and Lewontin Expression of class interest
  • Klopenburg Hybrid corn as agricultures
    Manhattan Project
  • Flow of germplasm from public to private sector

41
40
Distribution of Breeders
  • Frey survey (1996) showed 51 of SYs devoted to
    plant breeding RD in private sector
  • 5 years 2.4 loss in SAES, 10.7 gain in private
  • Private spends 338 M, public spends 213 M
  • 94 of corn SYs in private sector
  • 25 of all US plant breeding SYs in corn
  • Public soybean (35), wheat (59), cotton (23)
  • Pure line crops- public hybrid crops- private
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