More Evidence for a Blotch Dose Effect in Hulthemias

General Discussion
1

When crossing modern type roses to ‘Tigris’, most seedlings are once blooming and will not bloom during the first year. Some of the seedlings will not have a blotch, while some will have a light blotch and still others will have a good sized dark blotch. This later group seem often to be triploids in the way that they behave. When crossed again with modern tetraploids, most of the seedlings are non-remontant, however, a few will be repeat blooming and will bloom like normal modern rose seedlings after 8-10 weeks from germination. Most of these repeat blooming seedlings will lack the blotch, but a few will show a blotch. In my experience, all of these with blotches will be more attenuated as compared to the best F1 ‘Tigris’ seedlings.

The next step though changes things. If a repeat blooming dim blotched Hulthemia hybrid is crossed with another, there will be a few seedlings in the next generation that exhibit good blotches with intensity comparable to the best F1 ‘Tigris’ seedlings. It is these seedlings that appear to have 2 of the homologous chromosomes having the blotch gene(s).

Finally, when these seedlings with good blotches are crossed with regular modern roses, some of the resulting seedlings will get the 2 dose effect and will have good blotches. Below is an example of a cross that surprised me. It appears to be a regular HT in bud form, but when the petals are removed, you can see the blotch. This is a cross of ‘Gemini’ X “L83-4”.





Jim Sproul

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Interesting Jim!

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Jim, I am also interested in any observations you might have made regarding the interaction of the blotch with various colour as well. Do you think trying to establish diploid lines might help to consolidate the blotch whilst working on developing fertile progeny? Something Paul B said about a change in tack with his bracteata hybrids has me thinking whether a similar approach might be worth trying here with persica hybrids.

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One nice things that the more modern tetraploids can have is petal substance, which can be a con or pro for singles and semi-doubles trying to retain color in heat and rain.

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Jim, what you describe here makes me think of the blotch “gene” as a dominant gene, however it is capable of variable degrees of expressivity, depending on other suppressor genes that may suppress it totally or partailly in the new hybrids.

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Jim I know you said you tried crossing your hulthemias with stripes and it was not ideal. I was thinking that you should try to cross them with something like ‘Song of the Stars’ just to see how that works.

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Robert, this is the first bloom on this seedling, and as you know, the blotch nearly always gets 3 times larger and more intense as the seedlings mature, so I am thinking that the blotch may even be evident on opening buds next Spring.

Simon, I have noticed that certain colors tend to block expression of the blotch. I have seen this when crossing Hulthemias with whites, creams, yellows and multi-colored roses. It may be a single factor in common with these seedlings rather than the particular colors. A yellow non-Hulthemia seedling of mine that I used extensively in 2008 in crosses with Hulthemias having good blotches (producing 1,318 seeds), very few of the seedlings exhibited blotches, especially if the base color was yellow. There were a few good blotches in this group, but all of them had a more muddy tan to light muddy orange coloration - none were a good yellow with a good blotch.

In 2009, however, I did similar crosses with ‘Cal Poly’ at Mr. Moore’s suggestion. I thought that I would probably still wind up with few to no yellow Hulthemias, but to my surprise (from 518 seeds), there are several with a good yellow petal base and red blotches. It seems that my yellow seedling and ‘Cal Poly’, though both are yellow, are behaving very differently with respect to blotch expression.

Here are the petals of one of the seedlings first bloom from earlier this month. If the blotch size increases as expected with maturity, this one will have color and blotch size comparable to ‘Tigris’.



It might be interesting working with Hulthemia persica and other repeat blooming diploids, but I think that between Harkness and Ilsink, there will be repeat blooming Hulthemia-rose tetraploid hybrids widely available soon.

George, yes, I think dominant with variable expression is a good description of what I am seeing. Sometime the blotch is only a “hint” of a blotch - these disappear completely in the heat, so you have to be on the lookout for them in new seedlings.

Adam, I think that it will be interesting trying these with all types of roses. Speaking of stipes, I had a yellow orange stripe yesterday with a smaller red blotch at the base. Incidentally, it was in an open pollinated batch of seeds from a non-striped Hulthemia seedling that I was testing for germination - so a bee brought in the striped pollen!

Jim Sproul

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Jim, do you think crossing hulthemia with Jude The Obscure could result in the blotch expression being somewhat if not totally suppressed, since there is yellow in the petals? Have you dabbled with JTO in your hulthemia work?

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Cal Poly and Joycie are from the same lineage. Gold Badge isnt all that far related to R. foetida. With that said, Gold Badge related roses often bs here. Brass Band was one of the few exceptions.

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Hi George,

No I haven’t used JTO. I have a seedling of similar coloration that I use in English type rose crosses. It behaved very similarly as my yellow seedling mentioned above when crossed with Hulthemias. My guess though is that more than the apparent color of the rose, there is something else that is more “dominant” to the blotch gene(s) that results in little or no expression of the blotch if that other gene/factor is present. So I think that it would be more by trial and error to find whether a particular rose “allows” better expression of the blotch when crossed with Hulthemias.

Jim Sproul

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Ok, thanks Jim. It would be nice to know one day what mechanism(s) in the rose genome modulate the expression of this hulthemia “blotch gene”.

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Another example of what you say is Tigris itself, where its cream colored pollen parent(Trier) matched to persica did transmit the blotch.

13

My first hulthemia of the Livin Easy X Persian Sunset bloomed…

No evidence of a blotch. It looks nothing special I would expect from Livin Easy seedlings–

A very dark red.

although the leaves are very nice and Tigris-like. If it weren’t for the leaves, I would have though these were self pollinations.

If this is the only repeat blooming seedling of the batch, then I will keep it because I know it could be useful in the future. I could backcross it with another perisca hybrid in the future when more become available to the market.

14

Here is another repeat bloomer from this year’s batch. Both parents are repeat blooming Hulthemias. This one has few thorns, fairly upright habit at this stage, and sets hips well. This photo is from a cutting that I took of the original seedling.



I have used the original seedling in crosses both ways, even though uncertain of its fertility at this stage.

Jim Sproul

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Jim, that seedling is beautiful, congratulations.

Jim P

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It is a magnificent bloom.

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Looks great. Reminds me of, ‘Roses are Red’.

Link: www.helpmefind.com/gardening/l.php?l=2.38241&tab=36

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Jim very nice. it certainly has a very rich coloring. How color fast is it.

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Thank you all for the kind comments.

Robert, it reminded me of ‘Roses are Red’ too, the first time that I saw it. This one will be more compact I think and possibly with larger blooms. The petal count hints that it may be more semidouble when it matures. This photo was taken earlier this month, so the blotch is showing good heat stability.

Adam, the color looks great for most of the first day, but fades after that! There are others that do better with the fade factor, but this one has other characteristics that are looking good.

Jim Sproul

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Here is another new Hulthemia seedling that is showing good heat stability - we’ve been in the 100’s again…



It is a mini that seems to bloom a lot. It has upright bushy habit that is more rose-like than Hulthemia-like. There are others in this family that look good, but I think that this is the best. Both parents are repeat blooming Hulthemias.

Jim Sproul