In which one of the following combinations (a-d) of the number of chromosomes is the present day hexaploid wheat correctly represented
Combination Monosoic Haploid Nullisomic Trisomic (a) 21 28 42 43 (b) 7 28 40 42 (c) 21 7 42 43 (d) 41 21 40 43
D.
| (d) | 41 | 21 | 40 | 43 |
The present day wheat is hexaploid, known as triticale (2n = 42) with 3 genomes A, B and D i.e, AABBDD The 3 genomes are obtained from 3 different diploid species.
(i) Triticum aegilopoides -AA (2n = 14)
(ii) Aegilops speltoides - BB (2n = 14)
(iii) Aegilops squarossa - DD (2n = 14)
By crossing of first two diploids sps Triticum dicoccoides (2n = 28) i.e., tetraploid is produced AABB which on crossing with third species gives rise to Triticum aestivum (2n = 42) hexaploid (AABBDD). So its haploid set will have 21 chromosomes, monosomic (2n - I) will have 41 chromosomes, nullisomics (2n - 2) will have 40 chromosomes, and trisomic (2n + I) will have 43 chromosomes.
