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سيمينار المعهد
1. Agricultural Research Central
Plant Pathology Research Institute
Wheat Disease Department
Classical and molecular approaches in
wheat breeding to rust diseases
By
Dr. Mohamed Abdelkader
2. Introduction
• Wheat is the most widely grown and consumed
food crop in the world with a current annual
production level of more than 651 million tones on
a total production area of 217 million hectares.
• By the year 2050, the world population is
estimated to be 9 billion and the demand for wheat
will exceed 900 million tones (FAO 2012).
• Fulfilling this demand is very challenging in the face
of climate change, increasing drought, heat stress,
and emergence of new virulent diseases and pests.
3. Breeding progress
Breeding better cultivars has become a highly efficient way to improve plant
production for yield, quality and reduced input
Classical variety breeding
Determination of the ideotype, breeding
objective
Assesment of genetic variation, genetic
resources
Crossing + Evaluation + Selection
Screening, data management
Release of new variety
Maintenance breeding – stability of traits
Photoperiod insensitivity
cultivars
Shuttle breeding program at two
contrasting locations in Mexico,
wide adaptation
Semi dwarf cultivars
Norman
Borlaug
Borlaug was a plant
pathologist/breeder work
in developing new
varieties of wheat starting
in the 1940s spawned the
“Green Revolution,” and is
credited with saving at
least a billion lives.
4. Wheat Breeding Objectives
• High yield potential and broad adaptation
• Resistance to major diseases and insects
• Drought, heat, cold and salinity tolerance
• Grain quality
5. Pre breeding Program
• Commonly known as Genetic Enhancement or Germplasme
Development
• Pre-breeding is the most promising alternative to link genetic
resources and breeding programs.
• Pre-breeding refers to all activities designed to identify desirable
characteristics and/or genes from un adapted (exotic or semi-exotic)
materials, including those that, although adapted have been
subjected to any kind of selection for improvement.
1. Multi test locations even inside or outside the country at rust hot
spot
2. Estimate yield components and grain quality
7. Identification of wheat rust
resistance genes
Should be done at
pre breeding
program
Promising
lines
8. Identification of wheat rust resistance genes
• 1- Gene postulation( probable)
• 2- Genetic analysis
• 3- Using DNA markers
Advantages:-
1- Analysis can be done in several weeks
2- Easy when only a few genes are present .
Gene postulation
9. Disadvantages:-
1- A collection of races differing in virulence is required.
2- The presence of a gene is indicated but not proven.
3- This method used only in identification of resistance
genes that express in seedling plants and not
appropriate for the identification of resistance genes that
are expressed in adult plants.
4-When more than one effective resistance gene is present in a
cultivar or breeding line, the characteristic infection types of
the individual genes are often altered due to interaction
between the resistance genes.
10. 2- Genetic analysis
Advantages:-
1- Very accurate.
2-This method used for identification resistance
genes that express in seedling plants and also
appropriate for the identification of resistance
genes that are expressed in adult plants.
Disadvantages:-
1- This method needs at least 3 years for
identification any resistance genes .
11. Advantages:
• Detects variations directly at DNA level
• Not influenced by environment
• Numerous in number
• Automation is possible
Disadvantages:-
• Costs
• Trained peoples
Molecular techniques
12. Sources of variation
• Introductions: either as varieties or agermplasm
• Selection: Mass selection or individual plant selection
Hybridization: Genetic recombination through intra- and
inter- specific crosses
•Mutations
13. Efficient breeding program depends on
Definition of clear and priority objectives
Cultivar
resistance
Monogenic
resistance
Polygenic
resistance
Fast last
Durable
One specific race More than one race
15. • Understanding of genetics of traits.
• Availability of genetic variability and of parental
material.
• Selection effectiveness including team work, quality
testing, agronomic and molecular techniques.
• Breeding methodologies and population
characteristics.
• Adequate funding and respect of breeders property
rights.
16. We need to know about the pathogen population structure
and the available resistance sources in order to design a
resistance breeding program.
Collection of isolates
Phenotyping on host differential sets
Race structure
of pathogen
Sources of resistance
from host
17. Selection of Parents
“Mega-Varieties” with wide adaptation
ICARDA/CIMMYT lines with high yield
potential, disease resistance, and
grain quality
Regional or global performance in
International Nurseries
Disease reaction globally or in “hot spots”
Physiological characterization
DNA Marker data (specific primers)
18. Hybridization
1- Parents should be planted as single plant as possible
2- Parents should be planted in three successive
sowing dates at 15 days
3- Suitable spike must be taken
20. Single /Simple Cross
Bulk method
Pedigree method
•F2 plants planted
individually
•Each selected plant have a
number
•pure line
From f2 plants to f6
plants all of them
planted as bulk
25. Marker assisted selection (MAS)
•Marker-assisted selection (MAS) provides
opportunities for enhancing the response from
selection because molecular markers can be
applied at the seedling stag
•with high precision and reductions in cost
Molecular techniques
26. Marker assisted selection (MAS)
•For detecting single-major gene resistance, MAS
could be easily applied
• Marker-assisted selection is an efficient tool to
speed up plant breeding. It helps also in
pyramiding of resistance genes
