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BOTANY Higher Secondary Second Year - Textbooks Online

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Autopolyploidy<br />

Ploidy - flow chart<br />

Addition of one or more haploid set of its own genome in an organism<br />

results in autopolyploidy. Watermelon, grapes and banana are autotriploids,<br />

whereas apple is an autotetraploid.<br />

Allopolyploidy<br />

Increase in one or more haploid set of chromosomes from two different<br />

species result in allopolyploidy. Triticale is the first man made cereal. It<br />

is obtained by crossing a wheat Triticum durum (2n = 4x = 28) and a rye<br />

Secale cereale (2n = 2x = 14). The F1 hybrid (2n = 3x = 21) is sterile.<br />

Then the chromosome number is doubled using colchicine and it becomes<br />

an hexaploid.<br />

Parent Triticum durum x Secale cereale<br />

2n = 28 2n = 14<br />

(2n = 4x = 28) (2n = 2x = 14)<br />

F1 hybrid (sterile)<br />

2n = 21<br />

(2n = 3x = 21)<br />

Chromosome doubled<br />

(Colchicine treatment)<br />

2n = 42<br />

(2n = 6x = 42)<br />

Hexaploid Triticale<br />

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