unreduced gamete formation and its role in plant breeding
TRANSCRIPT
![Page 1: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/1.jpg)
1
Anilkumar. CPALM 3001
![Page 2: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/2.jpg)
2
Unreduced gamete formation
and
Its role in plant breeding
![Page 3: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/3.jpg)
3
Introduction
2n gametes
Sources and mechanisms
Detection and induction
Role in plant breeding
Conclusion
In this mother cell…
![Page 4: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/4.jpg)
Male gametogenesis
4
![Page 5: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/5.jpg)
Female gametogenesis
5
![Page 6: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/6.jpg)
An unreduced gamete has the same chromosome number as the plant that produced it i.e., 2n
They are also called 2n gamets or diplogametes
It is genetically controlled and results of modification of meiotic process
Contributed little to the origin of polyploids
Unreduced gametes
6
![Page 7: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/7.jpg)
Sources of 2n gametes
Interspecific hybrids: both 2n egg and pollen are produced
simultaneously by the same hybrid. but, neither of two
parents of the F1 hybrid nor their F2 sexual polyploidy
progenies can produce 2n gamets.
Ex: Lilium ( Barba-Gonzalez et al., 2005)
Wheat (Xu & Joppa, 2000; Zhang et al., 2010)
Citrus (Chen et al., 2008)
7
![Page 8: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/8.jpg)
Meiotic mutants
A mutant active gene in meiosis
2n pollen can formed independent from 2n egg cells and
vice versa.
Ex: Potato (Jongedijk et al., 1991; Peloquin et al., 1999),
Red clover (Parrot & Smith, 1984),
Alfalfa (Barcaccia et al., 2003),
Wheat (Jauhar, 2003; Roberts et al., 1999)
Arabidopsis (d’ Erfurth et al., 2008; Yang et al., 1999)
8
![Page 9: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/9.jpg)
Odd polyploids :
Crosses with triploids (gametes can be 1x, 2x or 3x) result
in higher ploidy levels of the progeny and mostly act as a
bridge between diploids and tetraploids
(Kohler, et al., 2010) 9
![Page 10: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/10.jpg)
Mechanisms of 2n gamete formation
Mitotic mechanism:
Somatic doubling, either obtained spontaneously or by the
application of chemicals at zygotic, embryonic or
meristematic stage of a plants life cycle.
This will ultimately lead to the production of polyploid tissues
and possibly the generation of polyploid offsprings.
Ex: Citrus Frequency of polyploids in citrus cultivars
(Usman , et al., 2006) 10
![Page 11: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/11.jpg)
Meiotic mechanisms:
Most commonly arise through meiotic defects
Abnormal meiotic processes resulting in gametes that
have the same chromosome number as that of parent
plant
This is mainly due to Meiotic Nuclear Restitution (MNR)
11
![Page 12: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/12.jpg)
1. First division restitution (FDR)
2. Second division restitution (SDR)
3. Indeterminate meiotic restitution (IMR)
4. Post meiotic restitution (PMR)
Other cytological aspects-
FDR and SDR
Cytomixis
Pre-meiotic doubling
4 types-
12
![Page 13: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/13.jpg)
(Brownfield and Kohler, 2010) 13
![Page 14: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/14.jpg)
Products of meiotic restitutions
(Gómez-Rodríguez, et al.,2012) 14
![Page 15: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/15.jpg)
Indeterminate meiotic restitution (IMR)
Display a mixture of FDR and SDR.
Failure of chromosome pairing
A part sister chromosome move to the same daughter cell.
The parental genomes are present in odd numbers.
15
![Page 16: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/16.jpg)
16
![Page 17: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/17.jpg)
Cytological aspects:
Other than FDR and SDR-
Cytomixis : chromatin from the nucleus extrudes to
cytoplasm of adjacent mother cell through cytoplasmic
connections (Sheidai et al., 2006) .
Pre- meiotic doubling: before meiosis
a doubling of the chromosomes occur
(Woogenvoort et al., 1990).
17
![Page 18: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/18.jpg)
Genes involved in 2n gamete formation
1. SWI1/DYAD
2. CYCA1;2/TAM
3. OSD1
4. AtPS1
5. dif1-1
6. PS- potato
7. el - maize
A. thaliana
18
![Page 19: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/19.jpg)
(Brownfield and Kohler, 2010) 19
![Page 20: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/20.jpg)
(A) Metaphase I
(B) dif1-1
(C) swi1-2
(D,E) swi1-2/dif1-1 double
mutant meiocytes.
(D) Sister chromatid cohesion is
lost at the end of prophase I.
(E) The resulting 20 free chromatids at
metaphaseI.
(F) Some cells contained 10
condensed univalents.
(Mercier et al., 2003) 20
![Page 21: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/21.jpg)
Frequency of unreduced gamete production
(Number of individuals producing 2n gametes/total number of individuals examined)
(Bretagnolle and Thompson, 1995) 21
![Page 22: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/22.jpg)
Factors affecting frequency of unreduced gamete production
Stimulated by environmental factors such as temperature,
wounding, water and nutrient stress……
Formation of giant pollen in Brassica inter specific hybrids
more viable than normal.
frequency is high under cold temperatures
these are two times greater than parents in terms of
magnitude
22
![Page 23: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/23.jpg)
(Mason et al.,2011)
Male unreduced gamete production in Brassica species under different temperatures
23
![Page 24: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/24.jpg)
Pollen viability estimates
(Mason et al.,2011) 24
![Page 25: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/25.jpg)
Techniques to increase frequency
25
![Page 26: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/26.jpg)
Detection of 2n gametes
1. Pollen morphology
2. Flow cytometry
3. Analysis of sporogenesis
4. Ploidy analysis of the progeny
26
![Page 27: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/27.jpg)
Pollen Morphology
• Banana, rose (Rosa) and sweet
potato 30% larger
• Chinis jujube (Ziziphus jujube) 1.5
times larger
(Xue et al., 2011)
Search for large pollen in the population
27
![Page 28: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/28.jpg)
28(Xue et al., 2011)
![Page 29: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/29.jpg)
FLOW CYTOMETRY
Direct quantification of pollen
nuclear DNA
-practiced in Lilly, tobacco, maize
and in rape –Pan et al., 2004
Compares the DNA content of pollen nuclei to the DNA content of somatic leaf tissue.
29
![Page 30: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/30.jpg)
(Chen and Gmitter , 2011) 30
![Page 31: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/31.jpg)
• Complex outer exine layer on the pollen surface is the main
obstacle in releasing the nuclei from pollen.
Bohne et al., 2003
Difficulties and solutions
• Bead beating
Roberts, 2007
• Chopping of pollen grains
Laere et al., 2009
• Nuclear isolation protocol which only releases nuclei from
germination tubes
Dewitte et al. (2006,
2009)31
![Page 32: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/32.jpg)
Alternative method to confirm the presence of 2n pollen
Analysis of microsporogenesis
Provide insight in the mechanisms (FDR, SDR) behind 2n
gamete formation.
Molecular cytological techniques like GISH, FISH or AFLP
markers can be used
Draw back: does not provide any information about pollen viability.
32
![Page 33: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/33.jpg)
Ploidy analysis of the progeny
Chromosome counting method
Flow cytometry
33
![Page 34: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/34.jpg)
Induction of 2n gametes
(Dewitte et al., 2012) 34
![Page 35: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/35.jpg)
(Nukui, et al., 2011) 35
![Page 36: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/36.jpg)
(Nukui et al., 2011)
Restoration of fertility in interspecific hybrids by N2O
36
Untreated N2O Treated
![Page 37: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/37.jpg)
(Barba-Gonzalez et al., 2006)
UNTREATED N2O TREATED
Germination of 2n pollen
37
![Page 38: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/38.jpg)
Trifluralin treatment
• Induced 2n pollen by submerging flower buds of Begonia in
a trifluralin solution.
Dewitte et al. (2010)
• Spraying maize tassels with a trifluralin solution before
flowering
Kato, (1999)
• Induction of both 2n pollen and 2n egg cells
38
![Page 39: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/39.jpg)
Effect of temperature
(Pecrix et al., 2011) 39
![Page 40: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/40.jpg)
Hibiscus syriacus Hibiscus paramutabilis
Interspecific hybridisation
X
F1 All are tetraploids
F2 50% are hexaploids
(Van Laere et al., 2009) 40
![Page 41: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/41.jpg)
Tools to engineer 2n gamete formation
Isolation of genes involved in 2n gamete production
Site-directed mutagenesis
Ethyl methane sulphonate (EMS)
Random insertional mutagenesis or irradiation of seeds or buds
41
![Page 42: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/42.jpg)
ROLE OF 2n GAMETES IN PLANT BREEDINGPolyploids that originate through the functioning of 2n gametes
(Peloquin, et al., 1999) 42
![Page 43: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/43.jpg)
Ploidy level manipulations in potato
(Carputo and Barone, 2005) 43
![Page 44: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/44.jpg)
Inter-genomic recombination
(Barba-Gonzalez et al., 2006) 44
![Page 45: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/45.jpg)
Interspecific Lilium hybrids
(Barba-Gonzalez et al., 2008)
2n gamete X diploid F1
2n gamete X tetraploid F1
45
![Page 46: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/46.jpg)
Use of 2n gametes in potato germplasm introgression
(Carputo, et al., 2000) 46
![Page 47: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/47.jpg)
AA
CCBB
AABB AACC
BBCC
B. rapa
B. oleraceaB. nigra
B. juncea B. napus
B. carinata
AABBCC
Super Brassica
Breeding “Super Brassica” cultivars
(Yan and Shyama , 2007) 47
![Page 48: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/48.jpg)
B. napus (AnAnCnCn)
X B. carinata (BcaBcaCcaCca)
AnCn BcaCcaGametes:
AnBcaCcaCn
Unbalanced tetraploidX B. juncea (AjAjBjBj)
Gametes: AnBcaCcaCn AjBj
Unreduced gametes
AnAjBjBcaCcaCn
allohexaploids
(Yan and Shyama , 2007) 48
![Page 49: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/49.jpg)
Amphihaploids in wheat
(Jauhar, 2007) 49
![Page 50: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/50.jpg)
50
Conclusion…
![Page 51: unreduced gamete formation and its role in plant breeding](https://reader036.vdocuments.us/reader036/viewer/2022062420/55c3c5debb61eb476f8b461f/html5/thumbnails/51.jpg)
51