Leen Leus's Resistence Breeding Rose Disease Ph.D Thesis



Link: archive.ugent.be/retrieve/2345/PhDLeenLeus.pdf

Very intresting Henry, thanks. They have R. Kordesii as being diploid, I thought I saw somewhere that it was tetraploid. can someone clear this up. Thanks.


“of the amphidiploid R. x kordesii in 1952.”

R. kordesii is listed in Modern Roses 11 as a tetraploid. However, I was also surprised to see Calocarpa listed as a triploid as Modern Roses 11 lists it as a diploid.

To have ones that differ from the Modern Roses 11 values (and not to state it) was unexpected because in the footnotes for Table 5.1, he states that when the ploidy level was different than found in the literature the alternate value was given in brackets.

Good question about ploidy levels. Leen is a wonderful woman and I really enjoyed meeting her last fall in Santa Barbara at the International rose meetings and visiting over supper one night. I think that part of the issue is that flow cytometry for many of the clones was used to estimate ploidy instead of direct chromosome counts. The overall quantity of DNA per cell can sometimes vary and lead to misclassifications. I counted and then recounted to make sure Bonica is triploid after Leen told me it’s tetraploid. I still count only 21 chromosomes. It’s sport ‘Royal Bonica’ also has 21 chromosomes. Perhaps for some of the clones listed the difference may be due to just flow cytometry being an indirect method known to lead to some misclassifications. Maybe labeling sometimes can get mixed up in gardens or at nurseries and actually different roses are being assessed under the same name.


It also says setigera is triploid. Im confused =P