Introduction to Plant Breeding

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14 Δεκ 2012 (πριν από 4 χρόνια και 6 μήνες)

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AGRI 201


Plant Breeding


S.K. Yau

Prof. of Agronomy

Outline of lecture


Introduction


Role of plant breeding in solving the global
food
-
population equation:
Green
Revolution


Role in improving quality



Introduction

What is Plant Breeding ?


“Plant breeding is the
genetic adjustment

of plants to the service of man” Frankel,
1958



Or simply, the
development of new plant
varieties






Breeding ?

How we carry out plant breeding?

Conventionally, by two major methods:

1.
Hybridization

2.
Mutation

Followed by years of selection and testing.


Lately, there is a new technique

What is GMO?


Genetic modified organism



Result of genetic engineering



Insertion of a specific gene from another
organism without using the conventional
techniques

Any urgent questions

on


GM crops?

Production and yield
-


what difference?


Production: amount
produced


For example:

Wheat production of
my farm was 33 t last
year.


Yield: amount per
unit area


For example:

Wheat yield of my
farm was 3300 kg
per hectare last year.


Why do we need plant breeding ?

to

improve

production

and

quality


increase

crop



increase

yield

area

/

intensity




per

unit

area




increase

input

e
.
g
.



improved

cultivar*



fertilizers,

irrigation


without

increasing

input



What advantages does plant breeding have
over cultural practices?


application

of

chemicals

to

control

pests,

irrigation,

&

fertilizers

must

be

repeated

for

each

season
.

Hereditary

improvement

is

more

or

less

permanent
.


usually

cultural

practices

cannot

improve

quality
.


unlike

chemicals,

environment

-

friendly
.





Green Revolution



What was it?

Is this the
Green
Revolution?

Is this the
Green
Revolution ?!

Green Revolution


Coined in 1968 to describe the dramatic impact
on wheat and rice production in developing
countries, especially Mexico, India, Pakistan,
and S.E. Asia by the
semi
-
dwarf varieties


Semi
-
dwarf wheat from the Rockefeller
Foundation


Government of Mexico Program


Semi
-
dwarf rice from the International Rice
Research Institute (IRRI)

N fertilizer (kg/ha)

Yield (t/ha)

What
caused
this
big
jump?

Increase in population and rice
production in Asia (1960 to 1980)

Population

55%

Rice yield

40%

Rice
production

60%

What would have
happened without the
dramatic increase in
rice yield and
production?

Area

Yield

Production

West Asia


and

North Africa

Was there a
green
revolution?


Achievement of breeding

on

quality improvement

Safflower

(
Carthamus
tinctorius
L
.
)

Fatty acid composition

0
10
20
30
40
50
60
70
80
Normal safflower
Oleic safflower
Olive
Oleic
Linoleic
Saturated
Safflower type and yield in
California (1950 to 1995)

Oil content of safflower cultivars
(1940 to 1995)

Bye!


Best wishes!


Hope to see you
again in my courses:

PLSC 255

PLSC 222


Thank you


Plant genetic engineering: why?


Can transfer genes from wide range of sources,
including non
-
plant materials. This is an advantage
over traditional breeding


Much more specific


Another possible advantage: needs shorter time


Major draw back: most breeding problems involve
many genes and cannot be solved by transfer of a
single gene


PLSC 255


Introductory Plant




Breeding



On
-
line course from Spring 2001
-
02
!

Syllabus


How to breed self
-
pollinating crops


How to breed cross
-
pollinating crops


Other techniques: polyploidy, mutation, tissue
culture, haploidy,
molecular markers, genetic
engineering


Important issues: crossing, field trials, genotype by
environment interaction,
germplasm resources and
conservation

Plant genetic engineering


= plant transformation


Transfer a segment of foreign DNA without
sexual hybridization


Products commonly known as genetic
modified (GM) plants

How (cont.)

Direct methods (create pores in plant cell wall to
let in DNA segment):


Incubation in certain chemical (simple, inexpensive,
but survival rate low)


Insertion by a particle gun


Electric shock (electrophoration, use high voltage
for a very short time)

How?

Indirect method via bacteria, virus, etc.:


Put foreign DNA segment into bacterial plasmid (circular
extra chromosomal DNA molecules)


Usually include a marker gene, e.g., an antibiotic gene, to
help selection of transformed plants later


Agrobacterium is the most widely used


Let the bacteria multiply and use them to infect the plants.
Hopefully, the genes will be transferred to the plant
chromosomes.

Be cautious!


There is much activity in the science of molecular
biology (new fashion?)


Some extravagant claims have been made about its
usefulness


Molecular genetic techniques surely will help
breeders, but have not replaced, and probably will not
be able to replace conventional plant breeding in the
foreseeable future.