All the unreduced cells in the flower would thus be Tetraploid.
From these approaches we now have a number of Tetraploid synthetic banana hybrids
and some have proved to be resistant to TR4.
If a Tetraploid wheat with 28 chromosomes is crossed with the diploid rye,
the result is a hexaploid plant with 42 chromosomes.
An example is the chimera built off of ES cells and Tetraploid embryos, which are artificially made by electrofusion
of two two-cell diploid embryos.
Ramsey compared the performance of the transplanted yarrows and found that the
hexaploid mutants had a 70 percent survival advantage over their Tetraploid siblings.
Some breeding programs have made Tetraploid plants by crossing triploid and diploid varieties,
but this depends on infrequent genetic events, and so it takes time and effort.
To test that idea, Ramsey took first-generation,
mutant hexaploid yarrow that were screened from a Tetraploid population, and transplanted them to the sandy habitat in the south.
The same result can be achieved by taking an infertile cross between species, the plant equivalent of a mule,
and exposing it to chemicals that cause it to double its chromosomes and become Tetraploid.