Is 'My Maryland' diploid?

I was surprised to find that Sarah Van Fleet was listed diploid given its hybrid tea parentage from ‘My Maryland’ but apparently not.

This of course suggests that ‘My Maryland’ is/was triplod or diploid.

Having looked at the parentage of ‘My Maryland’ it could well be diploid as it has more Tea blood than anything else, it only really has around 9-10% tetraploid blood (if that) from Jules Margottin so it seems more than likely.

I just makes me wonder how many diploids and fertile triploids there are among the hybrid teas.

Any thoughts?

Link: 'My Maryland' rose lineage

Try this link for Jink’s message.

Link: www.helpmefind.com/rose/pl.php?n=11462&tab=21&lstTyp=8

About Sarah Van Fleet: Modern Roses 8 that reports it as diploid and says also:

“Reported as R. rugosa x My Mayland but (diploid) chromosome count make this improbable.”

My Mayland seed and pod parents are registered as HT as is Victor Verdier (registered as HP as it predated the HT class) as well as quite prominent grand parent the very fertile Lady Mary Fitzwilliam*.

One can suppose that they have enough not tea features such as more frost resistance, larger flowers, more erect stems, stronger flower neck and are the sturdier more fertile tetraploids that then were bred for.

Surely if not intentionally.

*Being very fertile Lady Mary Fitzwilliam, a Tea x HT cross is evidently a teraploid.

Lady Mary Fitzwilliam: is most likely a fertile triploid or a diploid as its parentage is (Devoniensis (Tea)

Hi Jinks I am just guessing and friendly controversing.

Nevertheless I have a few points

First point:

Fertile triploids roses in my and others experiences never qualify for “very fertile”

Second: Fertile triploids are not so commonly occuring. This is a not very productive route I tried and am still trying as more promising than i.e. diploid x hexaploid crosses.

Third: Much more probable is diploid gamete from a diploid hybrid and instant fully fertile tetraploid seedling.

Well known and quite frequent: a usefull way at gaping ploidy levels.

Is’n it the way HT and Fl originated.

Last: Lady Mary Fitzwilliam ploidy is something David could eventually look at.

I was guessing it was tetraploid due to looking at the descendants of relations of My Maryland.

Also, Sarah Van Fleet may not be following everyday rules. Where did you find this diploid listing? Sometimes I come across conflicting ploidy lists.

The ploidy of ‘Sarah Van Fleet’ comes from Modern Roses

I must admit that I assumed that ‘Sarah Van Fleet’ was triploid and that ‘My Maryland’ was tetraploid.

But when you look at the bloodlines of ‘My Maryland’ it could be diploid, triploid or tetraploid. And as ‘Sarah Van Fleet’ is diploid ‘My Maryland’ must be diploid or triploid.

I think ‘Lady Mary Fitzwilliam’ is the key. If it is diploid (as it could well be) then ‘My Maryland’ would be diploid, if triploid then ‘My Maryland’ could be diploid, or triploid.

Either way it dose suggest that there are more fertile triploids around than we know. We tend to assume that HT’s and floribundas are tetraploid, but they all have fertile triploids in their heritage, some of which are very fertile.

With the mechanism enabling such fertility being transmittable to their offspring, there may well be a large number of fertile triploids among the HT’s and floribundas and possibly a few diploids amongst the older ones.

I just wounder if the ploidy of rose in these classes are as uniform as we assume them to be.

I’m interested in learning the ploidy of ‘My Maryland’ now too. If someone has a young plant or can take some softwood cuttings I can try to root, I can see what its ploidy is. I trust ‘Sarah van Fleet’ is diploid from looking at its pollen diameter and reading Modern Roses. There are a lot of triploids out there and even some triploid roses from crosses between two tetraploids (consider ‘Out of Yesteryear’). I have a handful of seedlings where this is the case. Anyway, there seems to be lots of surprises, especially as we work with roses with complex genetic backgrounds. Chromosome recognition and pairing can be unpredictable and seems to somewhat readily lead to offspring with unexpected ploidy levels.

Sincerely,

David

I think one of the assumptions being made is that tea roses are primarily diploids. This is probably true in most cases but this is not assured. There are more than a few triploid teas floating around. I believe one of the first teas to show up was Adam and if I’m not mistaken it has damask in it’s lineage via Rose Edouard. (So what is the tea rose origins any ways, china x gigantea ??) Maybe.

One could spend quite a bit of time speculating to ploidy but I tend to agree with Dave to be reasonably sure you would probably have to do a root tip squash or at least check pollen diameter.

Quite true John, there are undoubtedly triploid teas.

Having said that most of the tea roses in ‘My Maryland’s’ parentage are known diploids and seedlings of known diploid parents, but that doesn’t rule out mistakes in the recorded parentage.

When trying to establish ploidy by tracing parentage even the most educated guess is little more than speculation.

It is fun to speculate on these things from time to time though (keeps the rose mind active over winter).

Oh yes I do agree: it is fun to speculate on these things from time to time!!!

I grow ‘Sarah Van Fleet’ and its look is rather in the HT x rugosa class. Quite different from the few Tea x rugosa I did grow or look at.

All fertile triploids I met show at best reduced fertility. Among which there are a few thousends from my crosses. The best ones set as much hips as fertile tetraploids but with an average of 3 normal seeds that germinate rather badly. A distinctive feature.

Very fertile seedlings from triploids are suspectable to be tetraploids.

Yes John, Teas are a mixed lot. “Pink Teas” are mostly derived from Hume’s Blush and Bourbons hence often triploids while “Yellow Teas” are from Parks’s Yellow Tea-scented China and Noisettes and mostly diploids.

It has been shown and confirmed that many hybrid roses gametes be they ovules or pollen have unexpected ploidies reflecting some genetical disharmony.

When counted progenies show a steady excess of higher than expected ploidies. So much that I have yet to meet a confirmed diploid from a certainly triploid parent even if haploid gametes are known to be produced. I grew some but suspect the unwanted colaborating bees.

This observed tendency is reinforced by selection of the sturdier seedlings by the hybridizers.

Teas and polyanthas are so much more gracefull and resistant plants than actual HTs and Fls.

I have to agree with your last comment Pierre, that’s why I choose to work on the diploid level.

I’m convinced that there is more to be gained by crossing Teas, Polyanthas and the diploid species than is ever to be gained from trying to cure the HTs and Floribundas of their ills.

Time and experience may prove me wrong, but I’d sooner spend that time making my own mistakes than trying to correct other peoples.