Did the new poinsettias really have doubled chromosomes?

Factual Questions
1

I read that they have developed many different colors of ponsettias.

Originally, they just cross-bred for natural traits like durability indoors, as Mendelians have for centuries.

But now they irradiate the seeds (or the earlier pollen and ova?) and the result is doubled chromosomes. These are then quicker to produce variations, as the combinations per Mendel’s laws are suddenly squared.

So they have orange and peach and near-white and now purple.

Wouldn’t a change that major make them a new species?

2

Extra chromosomes (called tertraploidy or polyploidy, I think), do not means a new species. For example Down’s syndrome is caused by an extra chromosome 21 in people. While not along the same lines as having every chromosome doubled, you get the basic idea.

IIRC, many plants in fact do have doubled chromosomes (hawksweed, I think is one of them). The best test for whether or not something is a new species is if it can interbreed with the original species and produce fertile offspring. If this is the case, it’s not a new species. If it doesn’t produce offspring, or they are infertile, then it could be a new species.

Hope that this helps.

(And take everything with a grain of salt. I am not a genetsist…geneticsit… gene… genetics type guy, although I did just finish a second year genetics course.)

(I still wake up screaming.)

3

Creating tetraploid varities of ornamental flowers is very common. I know a Hemerocallis (daylily) breeder who claims to have heard rumors that some breeders run plants through an airport xray machine hoping for interesting mutations (this sounds unlikely to me).

Most tetraploidy–in Hems at least–is brought about chemically, rather than through radiation.

There. I’ve exhausted my knowledge on the subject.

4

Negative. F1 Hybrid plants are sterile but they are not new species.

5

Not yet-- They’re working on it though.
http://wwwnlh.nlh.no/ipf/forskning/Plantclb/breeding_of_pot.htm

Many of the newer varieties of Daylillies are Triploids though.

6

Whoops!

Thanks for the correction. As I said, genetics was the bane of my existence.

I was thinking along the lines of tigons, ligers, horses, mules, donkeys, etc. I was running under the assumption that if two animals produced fertile offspring, then they were of the same species, but if the offspring were sterile or nonexistent, then they were of separate species.

Now is this assumption correct, or am I mis-remembering what I was taught yet again?