Polyploidy in Plants: Formation, Types, Examples by Andreas Madlung and Luca Comai Note: This...
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Transcript of Polyploidy in Plants: Formation, Types, Examples by Andreas Madlung and Luca Comai Note: This...
Polyploidy in Plants:
Formation, Types, Examples
by Andreas Madlung and Luca Comai
Note: This powerpoint slide show is made available for teaching purposes for anyone interested. Some pictures are taken from the internet and may have copyright limitations. All slides can be customized to suit and are annotated with comments using the “Notes page” function in the Edit menu.
I. Autopolyploidy arises from genome duplication
species A
species A X
I. Autopolyploidy arises from genome duplication
species A
species A diploid(fertile)
X
I. Autopolyploidy arises from genome duplication
species A
species A diploid(fertile)
X
autotetraploid(fertile)
spontaneousgenome duplication
I. Autopolyploidy arises from genome duplication
species A
species A diploid(fertile)
X
autotetraploid(fertile)
spontaneousgenome duplication
Causes of genome duplication:a) meiotic non-reduction of gametes (both in egg and sperm)
b) genome duplication w/o cytokinesis (after fertilization)
species A
species BX
Duplicated genomes are fertile !!Botanical term: Allopolyploids
aborted gamete production
Hybrid ABbody cells
Hybrid ABduring meiosis
spontaneousgenome duplication
(fertile)
successful cell division
Hybrid AABB“allopolyploid”
II. Allopolyploidy arises from hybridization plus genome duplication
II. Allopolyploids are special kinds of hybrids
species A
species BX
III. Homologous pairing is predominant in allopolplyoids
sterile fertileGenome duplication
homologous pairing homeologous pairing
IV. Homologous pairing is predominant in allopolplyoids
V. Nomenclature for autopolyploids
Base number of chromosomes: X Humans: X=23
Gametic number: N Humans: N=23
Somatic number: 2N Humans: 2N=2X-46
VI. Diploid vs. Allopolyploid hybridization
selfing generations genomes maintained separately
Fluoresecent In Situ Hybridization (FISH) analysis can identify progenitor
chromosomes
A. arenosagreen probe
A. thalianared probe
Species-specific fluorescent probes made to two species: Arabidopsis thaliana and A. arenosa
Centromeric probe
Centromeric probe
What is the genomic composition of allopolyploid hybrids of A. thaliana and
A. arenonsa ?
Comai et al., Chrom. Research, 2003
sample 1
sample 2
sample 3
Allopolyploid cells
FISH: fluorescent in situ hybridizationred: A. th centromeric repeatgreen: A. are centromeric repeatblue: chromosome arms (DAPI stained)
Pollen mother cells: early Anaphase I
Black mustard
Chinese cabbage, Bok Choi
Cauliflower, broccoli, kale
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
rape seed
Indian mustard
Collard greens
Brassica nigra
Brassica rapa
Brassica olarecea
Brassica carinata Brassica juncea
Brassica napus
BB
AABB
AAAACC
BBCC
CC
picture sources: various www.
Allopolyploidy may lead to speciationExample: Speciation in the cabbage family
The cabbage family: “Triangle of U”
Black mustard
Chinese cabbage, Bok Choi
Cauliflower, broccoli, kale
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
rape seed
Indian mustardCanola-type oil seeds
Collard green, good for cold climatesbiodiesel
Brassica nigra
Brassica rapaBrassica olarecea
Brassica carinata Brassica juncea
N=8
N=9 N=10
N=10+8
N=10+9
Brassica napus
BB
AABB
AA
BBCC
AACC
N=9+8
CC
picture sources: various www.
In some cases allopolyploid speciation is a recurring phenomenon
Example: Tragopogon
picture
credit:http://www.botany.org/plantimages
Tragopogon dubius2N=12
Tragopogon miscellus2N=24
Tragopogon pratensis 2N=12
Tragopogon mirus2N=24
Tragopogon porrifolius 2N=12
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture. QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.