Title: From out of old fields comes all this new corn:
11
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
22
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
3Early 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
44
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
55
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(No Transcript)
76
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
87
Parents
1
2
3
4
Progeny Testing
1x2
75 Keep
2x3
35 Drop
1x4
90 Keep
98
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
109
Source
Johannsens Experiment
Select Within
Light
Heavy
Light
Heavy
Light
Heavy
1110
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
1211
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
1312
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
1413
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
1514
The Poor Soil of New England
1615
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
1716
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
1817
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
1918
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
2019
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
2120
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
2221
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
2322
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
2423
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
2524
2625
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
2726
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
28The 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)
2928
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.
3029
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
31Principles 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
32Charles 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
3332
England Boston Michigan Illinois Illinois
Illinois, CT Connecticut
1859 1860s 1880s 1890s 1890s 1900 1918
Natural Selection
34A 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
35Inbreeding 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
3635
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
37Composition 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
3837
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
3938
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
4039
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
4140
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