This document discusses gene pyramiding as a tool for developing durable resistance in crops. It defines gene pyramiding as combining two or more genes from multiple parents to develop elite lines with simultaneous expression of multiple genes. The objectives of gene pyramiding are to enhance traits, meet deficits in elite cultivars, and increase durability. Types of gene pyramiding include conventional pedigree breeding and backcrossing as well as molecular marker-assisted selection and transgenic methods. Gene pyramiding provides advantages like wider disease resistance and improved elite cultivars, while limitations include difficulty achieving multiple gene incorporation. Examples and applications in rice, wheat and other crops are also provided.

1. PRESENTED BY-
SACHIDANANDA BISSOYI
16LS05
MSc. LIFE SCIENCES
GENE PYRAMIDING:-
As novel tool for developing durable resistance
crop
1 4/5/2018

2. Topics covered
2
 Introduction
 Objective of gene pyramiding
 Types of gene pyramiding
 Examples
 Advantages of gene pyramiding
 Limitation of gene pyramiding
 Conclusion

3. Gene pyramiding -Introduction
 The development of molecular genetics and associated
technology like MAS has led to the emergence of a new
field in plant breeding-Gene pyramiding.
 The gene pyramiding aims at the derivation of an ideal
genotype that is homozygous for the favorable alleles at
all the loci.
 The term gene pyramiding is used in agricultural
research to describe a breeding approach to achieve
pest control and higher crop yield.
 It is mainly used in improving existing elite cultivars.3

4. 4
 Gene pyramiding or stacking can be defined
as a process of combining two or more genes
from multiple parents to develop elite lines
and varieties.
Or
 Pyramiding entails stacking multiple genes
leading to the simultaneous expression of
more than one gene in a variety.
Definition

5. Objectives of gene pyramiding
 Enhancing trait performance by combining
two or more complementary genes.
 Meeting the deficits by adding genes from
other sources to existing elite cultivar.
 Increasing the durability.
5

6. Types of gene pyramiding
• Pedigree breeding
• Backcross breeding
• Recurrent selection
Conventional technique
• Marker assisted selection
• Transgenic method
Molecular technique
6

7. Types of gene pyramiding
1. Conventional technique:
Serial gene pyramiding: Genes are deployed
in same plant one after other
 Pedigree breeding
 Backcross breeding
 Recurrent selection
7

8. 2. Molecular technique
Simultaneous gene pyramiding: Genes are
deployed at a time in a single plant.
Marker assisted selection
Transgenic method
8

9. 9

10. Marker assisted selection
 The use of molecular marker technology in
breeding to select progenies with the desired
genes is called marker assisted selection
(MAS),marker-assisted breeding or ‘smart
breeding’
 Marker-assisted selection (MAS) is a method
of rapidly incorporating valuable traits into
new cultivars.
 Pyramiding with the use of MAS is called as
Marker assisted gene pyramiding.10

11. 11

12. 12
F2
P2
F1
P1 x
large populations consisting of thousands
of plants
ResistantSusceptible
MARKER-ASSISTED SELECTION (MAS)
MARKER-ASSISTED BREEDING
Method whereby phenotypic selection is based on DNA markers

13. Distinct gene pyramiding
scheme
13

14. Marker-Assisted Backcrossing (MAB)
MAB has several advantages over conventional
backcrossing:
 Effective selection of target loci
 Minimize linkage drag
 Accelerated recovery of recurrent parent
1 2 3 4
Target
locus
1 2 3 4
RECOMBINANT
SELECTION
1 2 3 4
BACKGROUND
SELECTION
TARGET LOCUS
SELECTION
14

15. Conventional back crossing
DonorElite cultivar
Desirable trait
e.g. disease resistance
P1 x F1
P1 x BC1
P1 x BC2
P1 x BC3
P1 x BC4
P1 x BC5
P1 x BC6
BC6F2
Discard ~50% BC1
Repeat process until BC6
Recurrent parent genome recovered
Additional backcrosses may be required due to linkage drag
Bert Collard & David Mackill. MARKER-ASSISTED BREEDING FOR RICE IMPROVEMENT
• High yielding
• Susceptible for 1
trait
• Called recurrent
parent (RP)
P1 x P2
15

16. Concept of ‘linkage drag’
 Large amounts of donor chromosome remain even
after many backcrosses.
 Undesirable due to other donor genes that
negatively affect agronomic performance.
Donor/F1 BC1
c
BC3 BC10
RECURRENT PARENT
CHROMOSOME
DONOR
CHROMOSOME
TARGET
LOCUS
LINKEDDONOR
GENES
TARGET
LOCUS
16

17. Conventional backcrossing
Marker-assisted backcrossing
F1 BC1
c
BC2
c
BC3 BC10 BC20
F1
c
BC1 BC2
 Markers can be used to greatly minimize the
amount of donor chromosome….
TARGET
GENE
TARGET
GENE
Bert Collard & David Mackill. MARKER-ASSISTED
BREEDING FOR RICE IMPROVEMENT17
Only two BC generation, the
target segment can narrowed down
by 2cM by MAS and completely
diminish linkage drag of donor
parent.

18. Backcrossing strategy
 The marker assisted backcross based gene
pyramiding can be performed in three strategies.
Fig. 4: Different schemes of backcrossing for gene pyramiding. RP-
Recurrent parent; DP- Donor parent; BC- Backcross; IRP- Improved recurrent
parent. A. Stepwise transfer; B. Simultaneous transfer; C. Simultaneous and18

19. Table 1 below shows the successfully pyramided genes with
their traits of some important crop plants, rice, wheat, cotton,
pea, barley, broccoli, soyabean and chickpea.
19
Examples

20. Gene Pyramiding for three genes of
rice blast resistance in rice
Jian-Long Xu, Institute of Crop Sciences, CAAS. Molecular Marker-assisted Breeding in Rice
20

21. Advantages gene pyramiding
1) Widely used for combining multiple disease
resistance genes for specific races of a
pathogen.
2) Important to develop 'durable' disease
resistance against different races .
3) Main used to improve existing elite cultivar.
4) Eliminates extensive phenotyping
5) Control linkage drag
6) Reduces breeding duration
21

22. Limitation of gene pyramiding
22
 Lots of efforts have to made to incorporate
several major gene into single cultivar.
 Pyramiding is extremely difficult to achieve using
conventional methods.
 It is very difficult to interrogate one gene from one
cultivar or one species to another one by
conventional method.
 Stability of all desired gene in one plant is another
issue which limited the “Gene pyramiding”

23. CONCLUSION
23
 Gene pyramiding is an important strategy for
germplasm improvement.
 Gene pyramiding with marker technology can
integrate into existing plant breeding programmes
all over the world to allow researchers to access
transfer and combine genes.
 MAS based gene pyramiding has the potential to
increase the rate of genetic gain.

24. REFERENCES
24
 Gene Pyramiding: An Overview Ashok Kumar Malav*, Indu and Kuldeep
Singh Chandrawat. Int. J. Curr. Res. Biosci. Plant Biol. 2016, 3(7): 22-28
 Allan, R. E., Peterson, C. J. Jr,, Rubenthaler, G. L., Line, R. F., Roberts,
D. E., 1989. Registration of „Madsen‟ wheat. Crop Sci. 29, 1575-1576.
 Ribaut, J.-M. & Hoisington, D. 1998 Marker-assisted selection: new
tools and strategies. Trends Plant Sci. 3, 236-239.
 Durable Resistance of Crops to Biotic Stresses Mekonnen et al., J Plant
Pathol Microbiol 2017, 8:6
 Jian-Long Xu, Institute of Crop Sciences, CAAS. Molecular Marker-
assisted Breeding in Rice
 Gene Pyramiding Using Molecular Markers- Francis etal., 2012
 Gene pyramiding-A broad spectrum technique for developing durable
stress resistance in crops.- Joshi et al.,2010

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