Allopolyploids are polyploids that contain genetically distinct chromosome sets from two or more species. Natural allopolyploids originate from chromosome doubling of an F1 hybrid produced by natural hybridization between distinct species. Experimental allopolyploids are produced by doubling the chromosomes of an F1 hybrid using colchicine. New world cotton (Gossypium hirsutum) is an example of an allopolyploid, as it originated from an F1 hybrid between old world cotton (G. herbaceum) and American cotton (G. raimondii) that had its chromosomes doubled. However, the original F1 hybrid was sterile with abnormal meiosis and could not

1. An assignment on
ALLOPOLYPLOIDY IN COTTOn
Submitted to : Submitted by:
Dr. K.K Panigrahi Rajendra Kumar Ojha
Asst. Professor 2nd year B. Sc (Ag)
PLANT BREEDING AND GENETICS 42C/15

2. ALLOPOYPLOIDS
• Allopolyploids: A polyploid containing
genetically different chromosome sets from
two or more species is known as
allopolyploid.
• The prefix “allo” indicates the involvement of
non-homologous sets of chromosomes

3. ORIGIN OF ALLOPOLYPLOIDS
Natural allopolyploids most likely originate through
chromosome doubling of F1 hybrid produced by chance
through natural hybridization between two distinct species
of the same genus or from different genera. Experimental
production of allopolyploids is achieved through
chromosome doubling of F1 hybrid with the help of
colchicine. Such allopolyploids are often called synthetic
allopolyploids. The synthesis of allopolyploids involves two
steps.
1. Production of F1 hybrids by crossing two distinct species
and
2. Chromosome doubling of such F 1 hybrids. The man made
cereal Triticale is an example of synthetic allopolyploid

4. VARITIES OF COTTON

5. • The new world cotton (Gossypium hirsutum) is an
interesting example of allopolyploidy.
• J.O. Beasley crossed old world cotton (Gossypium
herbaceum) with American cotton (Gossypium
raimondii) and doubled the chromosome number in
F1 hybrids.
• The allopolyploid thus produced resembled the
cultivated new world cotton (Gossypium hirsutum)
and when crossed with it gave fertile F1 hybrids.
• These results thus suggested that tetraploid cotton
(Gossypium hirsutum) originated from two diploid
species namely Gossypium herbaceum (2n = 26) and
Gossypium raimondii (2n = 26).

6. A= G.herbaceum, B=G. raimondii, C=F1 hybrid
F1 hybrid
•Characters obtained from A= The colour of glands,anther
cases,pollen and corolla.
•Characters obtained from B= The colour of staminal columns and
filaments.

7. DRAWBACKS
•THE F1 HYBRID OBTAINED WAS STERILE.
•THE HYBRIDS COULD NOT PRODUCE BOLL-SET.
•CYTOGENETIC ANALYSIS CONFIRMED ABNORMAL
MEIOTIC BEHAVIOUR EXISTED IN HYBRIDS.

9. REFERENCE
•Dr. Kaushik Kumar Panigrahi
Asst. Professor
Plant breeding and genetics
(C.A. Chiplima)
•Wikipedia
•www.ncbi.nim.nih.gov
•scholar.google.co.in