I've got twins!

Rose Genetics Ploidy Level
, , , , , , , , , ,
1

In late January I noticed a seed with a root so planted it and watched carefully for the emergence of the seed leaves. They seemed slow to arrive so I periodically uncovered it to see what was taking it so long. The root grew longer but was thin and didn’t look well. On one of my checks I noticed what looked like another root emerging from the seed (half the outer shell was still in place along with the brownish inner seed skin–thingy). I waited a couple more days then decided to help it along. With tweazers I carefully pulled on the skin-thingy and the long thin root held firmly in the soil and its two little seed leaves emerged. But the shorter stubby root was still coming out of the thingy. So, again with the tweazers, I pulled away the thingy and a second set of seed leaves attached to the stubby root emerged. Voila! Twins…by C-section no less!

As of today the stubby one has got its second true leaves coming on but the first seedling hasn’t got any true leaves and is very, very small. And then my 3 year old climbed on to the washer and dug it up. So, even with the best of care, it wasn’t thriving. And I seriously doubt it will survive the attention of “the girl who must touch everything”.

I emailed Dr. Byrne at Texas A&M who said he hadn’t seen twins in roses but had heard of them in peaches. Has anyone else out there seen anything like this? I’d love to hear any input. Also last year I had a seedling with a photosynthetic mutation. It couldn’t photosynthesize at all. Needless to say it didn’t survive long. It was fascinating in its pale yellow spookiness though.

I’m pretty sure theres nothing radioactive in my back yard but I’ve got a pretty high rate of wierdness for only 8 seedlings (last year and this combined).

Any comments will be welcome.

Julie

2

Do you think it might have actually been two seeds that fused together somehow inside the hip?

3

See:

http://www.rosehybridizers.org/forum/message.php?topid=3531#3531

Link: www.rosehybridizers.org/forum/message.php?topid=3531#3531

4

Hi Julie,

Yes, Twins happen often enough. If the seedling were in the same papery covering there is a strong chance that the smaller twin is a haploid- with the same genetic makeup as the egg. In an ovule the haploid nucleus divides to make 8 copies. One copy is used for the egg, two more are called synergids, 3 for antipitals, and the last two for the central cell which becomes fertilized to form the endosperm. Sometimes a synergid can form into an embryo. I have gotten two haploids out of ‘Dorcas’ this way and also some more from some seedlings of mine. The haploids are often very weak and often are challenging to have survive.

More commonly, there are two separate embryos with their own papery covering and genetically distinct within a rose seed when twins occur. However, it sounds like yours may be in the same papery covering.

Often twins, especially those from the same testa, are hard to identify. People growing rose seedlings commercially or in a large way have technicians doing the hands on work that may not be aware of the significance and also the weaker one may not emerge and survive.

Hope your smaller baby survives.

Keep us posted.

Sincerely,

David

P.S. I have a manuscript that will be coming out where I mention and include data from a couple of these haploids derrived via twin embryos. I’m excited to get it in print. I also had twin embryos with separate testas that I think are identical twins from looking at them morphologically and also running them on a couple extra lanes in one of my DNA gels.