Question for David


Regarding your rose that has three alleles for repeat bloom, are there any outward signs that it may have three alleles? Like a limited repeat in the fall or a prolonged bloom in the spring? Anything that gave you an inkling. Or were you just pleasantly surprised when you crossed it with a repeat blooming plant and 50% of the seedlings had repeat bloom?

If there are any signs then that would help in the culling and selection process for which seedlings to keep for future breeding purposes.



That’s a great question Paul. No, there is no obvious signs for most of them I have that are Rrrr. Most do not have stray fall repeat bloom. Their repeat blooming seedlings are very good repeaters though. Roses that typically do not have any fall rebloom I suspect are better in segregating for good repeaters later surprisingly.

Those that are one time bloomers for the most part, but do throw some stray repeat towards fall sometimes (Rosa laxa for instance), I think are more challenging at times to work with. I think that there are additional genes that modify or influence the one time blooming gene to modify expression of that rebloom trait. In the future these additional genes and alleles can bring about stingy repeaters or awkward repeat. I think the genes that modify Rosa rugosa’s true repeat gene/ alleles to supress it while the seedlings are juvenile, keep segregating and result in poor or limited rebloom in many of the Explorer (Kordesii types) rose offspring (not all of course) even once they are mature. I suspect mixing the rugosa genetics with other classes of roses can mess up turning those off after the plant is mature. I think the clearly non-repeat bloomers (like my Rosa virginiana, R. setigera, and R. palustris clones) give better repeaters later because they don’t have extra genes and influences that interfere with the major one time blooming gene to allow for a bit of rebloom or supressor genes for the major repeat blooming allele in rugosa.

I just do some progeny tests in advanced seedlings to see what ratio comes out of repeat bloomers and then focus on those as parents eventually that give more repeaters and have other good traits. By the time I select for disease resistance and hardiness, there really aren’t too many left to do progeny tests with.



Hi David,