Select the correct statements about origin of the tetraploid and hexaploid wheat:
• [A.] The tetraploid species Triticum turgidum is an allopolyploid.
• [B.] The hexaploid species Triticum aestivum is an allopolyploid.
• [C.] Triticum turgidum arose from a combination of Triticum monococcum and Triticum timopheevii genomes.
• [D.] Triticum aestivum arose from a combination of Triticum turgidum and Aegilops tauschii genomes.
Select the correct statements about origin of the tetraploid and hexaploid wheat:
• [A.] The tetraploid species Triticum turgidum is an allopolyploid.
• [B.] The hexaploid species Triticum aestivum is an allopolyploid.
• [C.] Triticum turgidum arose from a combination of Triticum monococcum and Triticum timopheevii genomes.
• [D.] Triticum aestivum arose from a combination of Triticum turgidum and Aegilops tauschii genomes.
Show Hint
- A genome donor: Triticum monococcum
- B genome donor: Aegilops speltoides relative
- D genome donor: Aegilops tauschii
- (A), (B) and (C) only.
- (A), (B) and (D) only.
- (A), (C) and (D) only.
- (B), (C) and (D) only.
The Correct Option is B
Solution and Explanation
Cultivated wheat evolved through natural hybridization events followed by chromosome doubling, a process known as allopolyploidy.
Step 3: Detailed Explanation:
Let us analyze each statement regarding wheat evolution:
- Statement A is correct: Triticum turgidum (durum wheat) is an allotetraploid (\(2n = 4x = 28\)) with the genome formula AABB.
It arose from the hybridization of diploid einkorn wheat Triticum monococcum (AA) and a wild diploid grass related to Aegilops speltoides (BB).
- Statement B is correct: Triticum aestivum (common bread wheat) is an allohexaploid (\(2n = 6x = 42\)) with the genome formula AABBDD. It contains chromosome sets from three distinct diploid ancestors.
- Statement C is incorrect: Triticum turgidum (AABB) did not arise from Triticum timopheevii.
Triticum timopheevii is a different allotetraploid wheat species with the genome formula AAGG.
- Statement D is correct: Triticum aestivum (AABBDD) arose from the hybridization of tetraploid wheat Triticum turgidum (AABB) with the wild diploid goatgrass Aegilops tauschii (DD).
Therefore, statements A, B, and D are correct, while C is incorrect.
Step 4: Final Answer:
The correct combination of statements is (A), (B), and (D) only, matching Option (B).
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