POLYPLOIDY BREEDING

2. POLYPLOIDY BREEDING
It is a type of plant breeding that uses polyploid plants
to produce new hybrid plants. Polyploidy is a condition
in which a plant has more than two sets of
chromosomes. This can happen when a plant’s cells
divide incorrectly, or when a plant is exposé to
radiation or certain chemicals.

4. Polyploidy

5. Suitability of a crop for polyploid breeding
depends on following factors:
⦁ Crops which are not seed propagated(ie, vegetatively
propagated crops where the economic part is not
seeds)
eg: forage crops, tubers, sugarcane, ornamentals
⦁ Allogamy / cross pollination
eg: Poaceae against Leguminosae

6. ⦁ STEP 1
Artificial induction and/or collection of naturally
occuring polyploids and their maintanence.
⦁ STEP 2
Detection of different kinds of polyploids.
⦁ STEP 3
Isolation and handling of polyploids.

7. Polyploid breeding includes:
1. Monoploid/Haploid breeding
2. Autoploid breeding
3. Allopolyploid/Amphi(di)ploid breeding
4. Aneuploid breeding

8. STEP 1 PRODUCTION OF HAPLOIDS
i. By induced parthenogenesis
◦ Using incompatible or irradiated pollen, haploids
can be obtained by parthenogenesis.
ii. Through wide crosses ( cross with distant species)
◦ eg: Hordeum vulgare х Elymus areanus
Monoploid barley

9. iii. Through chromosome elimination technique in
distant crosses
◦ eg: Bulbosum technique
H.vulgare х H.bulbosum
(2n=2x=14) (2n=2x=14)
Hybrid embryo
Haploid barley
(2n=x=7)
(H.bulbosum chr. eliminated)
eg: Solanum nigrum x S.luteum

10. iv. Cell culture/Tissue culture technique
v. Anther culture technique by Guha and Maheswari
◦ Used in Datura, Nicotiana, Brassica, rice, wheat,
triticale etc.
◦ Tanfeng is a haploidy derived rice variety
developed in China(1976)
vi. Through pollen culture
◦ Haploid pollen grains develop into haploid plants.
◦ Nicotiana – readily responding in anther & pollen
culture.
Technique to be followed varies depending on the
species.

11. STEP 2 DETECTION OF HAPLOIDS
i. Detection through genetic markers
◦ Use of recessive & dominant genetic markers
associated with seedling characters such as
hypocotyl colour is useful in early detection of
haploids.
◦ Eg : In potato, a dominant purple spot is present
on haploid embryo-helps to distinguish at seed
stage.
ii. Through plant morphology
◦ Haploid plants are inferior to diploids – shorter,
less longer leaves, reduced in breadth, stomata &
guard cells – smaller in size.

12. STEP 3 DIPLOIDISATION
⦁ Colchicine treatment – most effective & widely used
method.
⦁ Acts as inhibitor of spindle formation during mitosis &
causes duplication of homologus chromosomes
⦁ Colchicine is readily soluble in cold water, alcohol and
chloroform but less soluble in hot water.
⦁ Used as aqueous solution – relatively unstable. So the
solution prepared fresh before each application.
⦁ Affects only dividing cells-applied to actively dividing
meristematic cells repeatedly at brief intervals.

13. ⦁ Includes triploid and tetraploid breeding
I. TRIPLOIDBREEDING
• Produced by crossing tetraploid and diploid (4n x 2n)

15. ⦁ Varieties Shonima & Swarna (2015) released from
Kerala Agricultural University

16. ⦁ Variety Ocean
2x
3x

17. II. TETRAPLOIDBREEDING
⦁ Produced by chromosome doubling from diploid plants

18. ⦁ Possible in tobacco, Petunia etc.
⦁ Autotetraploid maize has 43% more carotenoid
content & vitamin A.
⦁ Successful in forage crops, ornamentals etc.
Pusa giant berseem -1st autotetraploid variety
(Egyptian clover) released for large scale cultivation –
higher green fodder yield
Vetiver variety – Sugandha – 11% more oil yield

19. ⦁ AMPHIDIPLOID – Allopolyploids diploid for all
genomes present.
⦁ STEP 1 Production of F1 hybrids by interspecific
and intergeneric crosses
⦁ STEP 2 Chromosome doubling by colchicine

20. DD)

22. 4

23. ⦁ Developed by Karpechenko
Chr.doubling

24. ⦁ Combines yield potential and grain quality of wheat &
disease and environmental tolerance (including soil
conditions) of rye

25. ⦁ Irregular variation in chromosome no.
⦁ By meiotic irregularities such as non-disjunction or
lagging behind in metaphase plate result in n+1 & n-1
gametes. These gametes fertilized by normal gametes
produce aneuploids.
⦁ In desynaptic and asynaptic plants-a no.of univalents
are seen in mid metaphase instead of bivalents which
produce aneuploids
⦁ Triploid plants produce aneuploid plants
⦁ Tetrasomic plants produce aneuploid gametes resulting
in aneuploid progeny.

26. THANK YOU...