In this chapter, you read that bread wheat (Triticum aestivum) is an allohexaploid, containing two sets of chromosomes from each of three different parent species. Genetic analysis suggests that the three species pictured following this question each contributed chromosome sets to T. aestivum. (The capital letters here represent sets of chromosomes rather than individual genes, and the diploid chromosome number for each species is shown in parentheses.) Evidence also indicates that the first polyploidy event was a spontaneous hybridization of the early cultivated wheat species T. monococcum and a wild Triticum grass species. Based on this information, draw a diagram of one possible chain of events that could have produced the allohexaploid T. aestivum.

Short Answer

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The hybrid crosses are done among three-parent species of wheat (Triticum monococcum, wild Triticum, and wild T. tauschii), contributing to the production of T. aestivum. The spontaneous cell division error will lead to the doubling of diploid chromosome number and result in the formation of a sterile hybrid zygote.

Step by step solution

01

Bread wheat

Bread wheat possesses the scientific name T. aestivum. It resides under the grouping of the most significant crops in the world. Its domestication corresponds with the commencement of farming, and ever since, it has been continually under the choice of human beings.

02

Einkorn

Einkorn is another name for the species of wheat Triticum monococcum. These species fall under the category of diploid ancestral wheat. They exhibit an association with durum and bread wheat.

03

Diagram that indicates the spontaneous hybridization of the early cultivated wheat species T. monococcum and a wild Triticum grass species

The ancestral species of wheat are described as T. monococcum, Wild Triticum, and wild T. tauschii. So, first, the fusion of species T. monococcum and Wild Triticumoccurs. This results in the formation of AB which is sterile species.

Afterward, both species (T. monococcum and Wild Triticum) fuse with the third species, which is wild T. tauschii. This results in the formation of ABD, indicated as T. aestivum. It is also called bread wheat. This is again a sterile species.

So, the above diagram explains this process. The species named T. aestivum is formedfrom the fusion of the ancestral species of wheat.

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