Triploid R. pomifera seedlings to share

Rosa Pomifera is a Caninae section species which typically is tetraploid. It should have 3 sets of chromosomes in the egg and one in the pollen due to being a Caninae section species. I obtained a 3x seedling through parthenogenesis. This 3x seedling is quite fertile and selfs readily. The limited number of these selfs I confirmed are also 3x. So, it may be producing 2x eggs and 1x pollen. This is very interesting in light of some recent report describing the two chromosome sets which pair in order to produce the 1x pollen in general in Caninae section species are very similar and preferentially pair. This 3x fertile R. pomifera seedling may suggest that another set of chromosomes or various homologs can substitute for one of these sets which typically preferentially pair. In any case, crossing these triploids as females with 4x modern roses will probably produce tetraploid hybrids having half R. pomifera chromosomes. If one used the standard tetraploid species that one would offer 3 sets of R. pomifera in the egg. It may be easier to develop repeat blooming descendants by limiting the female contribution of R. pomifera genes using these triploids.

R. pomifera is shade tolerant, hardy, has velvety fragrant leaves, and is an early bloomer. It may produce some very unique hybrids. In addition, the orginal 3x hybrid and its seedlings seem more vigorous than 4x plants. This may be due to a reduction in ploidy and faster growth rates conferred by reduced ploidy. Increased ploidy is often associated with larger plant parts, but also at times reduced growth rates.

If you would like some seedlings of this 3x R. pomifera (selfs- very early bloomer and only thing in bloom at the time), please contact me with your name and mailing address. The seedlings are in 6-packs now. I’ll try to send each person a few plants. I think these seedlings are a great resource and have more than I can handle.


David Zlesak

Four people are interested in some seedlings. There are more left. I hope to send them out this Monday or Tuesday and then this coming week clean up the basement and toss the extras. If someone else would like some let me know soon. Thanks, David

Very interesting… How did you induce parthenogenesis?

Hi Jim, Yeah! I was excited to find it. For those that don’t know what parthenocarpy is, I came across this definition online “the growth and development of an embryo or seed without fertilization by a male”. There were twin embryos with one 4x seedling and one 3x seedling. They shared the same testa (papery covering inside the hard seed. Often with twin embryos one is fertilized normally and the other is haploid derived from a synergid, so it is genetically the same as the egg that was fertilized. With many other twin sets from modern 4x roses, the weaker twin often dies (for me at least). These weaker twins need to be babied along and unless someone is transplanting very young germinating seedlings they are often overlooked and may not even emerge from the soil with the larger seedling. Perhaps since this 3x R. pomifera is a Caninae section species and the egg would be 3x, it happened to be healthier and have less unmasked, deleterious genes. I wish I had the resources and connections to collaborate with the Europeans who are doing cytology work with Caninae section species and following meiosis. These triploids may offer some insight into pairing and genes on the genomes contributing to Caninae section roses and their unique meiosis. I’m glad to share them now just to help ensure that if something bad happens to my plants (or me) others will have it and know what it is and also begin to make progress hopefully with this line.