Okay, I understand how caninea meiosis effects my breeding work in a partical way, but I have no idea what is actually going at the cellular level. My current biology teacher at the college is primarily a zoologist, and didn’t even know that there were plants which did such goofy things with their chromosomes, so I can’t find anyone to explain it to me, nor and reference material that explains it. Does anyone what exactly is going on? Is there a different meiosis process for producing eggs and pollen or what?
Here is a paper that describes some aspects of Caninae meiosis.
Thanks! The first was a tad over my head, but I’m going to sit down with it and get it all figured out. I love learning new things!
Caninae meiosis is really intriguing! From the papers I’ve read I boiled down this odd type of meiosis to there being only two sets of seven chromosomes pairing in meiosis. The rest of the sets of chromosomes remain as univalents (all by themselves). The paired sets of chromosomes form seven bivalents (seven pairs of two chromosomes). The paired bivalents segregate as normal. In the female gamete all the univalents plus one set of chormosomes that were bi valently paired are found and in the male gamete the univalents are lost and only one set of chromosomes from the bivalent is found. This way the female has all but one set of chromosomes and the male has just one set of chromosomes.
It’s interesting how the univalents behave on the female side and are retained. In general univalents tend to lag behind during meiosis and are often lost. Somehow they are lost on the male side and retained on the female.
I don’t understand how Albas (hexaploid) can have two sets of chromosomes in the pollen and four in the egg. They do have R. canina as a founding species. Perhaps instead of having just two sets of chromosomes pair they have four sets pairing two by two (as bivalents instead of tri or quadrivalents) and the rest of the chromosomes are univalents. In the egg one set of chromosomes from each of the two sets of bivalents plus the 14 univalents allow the egg to have 28 chromosomes and the male gamete is able to have 14 chromosomes because the univalents are lost and one set of chromosomes from each set of bivalents are retained. Does someone know if this is this the case?
If there are only 14 chromosomes in the pollen dose this make it diploid and easily mated with r. rugosa?
A diploid like R. rugosa has only 7 chromasomes in the pollen. It should be supposidly possible to cross R. rugosa (seed) with pollen from any Caninae section rose (except the Albas) and get a diploid offspring. Caninae meiosis does produce a large number of un-viable pollen cells, so it may take some work to get that to happen.
Isn’t this cool stuff!
As Joan indicated R.rugosa will produce offspring from Caninae pollen. I had rugosa x eglanteria seedlings that were pathetic little things but definitely hybrid; and rugosa x glauca which are still alive and well and also definitely hybrid. Both of these hybrids, although technically diploid (14 chromosomes) had fertility problems. The rugosa x eglanteria was very sterile (never producing a single seed); the rugosa x glauca produces occassional seeds but the resulting seedlings have so far been disappointments. I’m thinking that conversion to 28 chromosome level using chemical treatment (trifluralin or colchicine) may be the best direction to head in with the rugosa x glauca F1. Or backcrossing to the rugosa, to increase chances of obtaining healthy, more fertile, repeat blooming hybrids.