Double Bloom as a Dominant Trait

[Darkhorse]

So, I've been casually doing research on this topic for the past few months.  Not formal research by any means, but spending time on my computer looking through hibiscus family trees. 

My tentative theory-- I say tentative because I'm still not 100% on this-- is that being a double is a dominant trait in hibiscus blooms.  Dominant, for the genetics layperson, means that if an organism has that particular gene, it is always expressed.  In other words, if a hibiscus can bloom as a double, it must have at least one parent that can also bloom as a double. (i.e. lots of doubles have Rosalind as a parent, for instance)

I also feel that the penetrance of the "double" gene varies greatly.  Penetrance is how much the gene actually shows up.  For example, a hibiscus that has the gene for blooming as a double sometimes will only express this through having extra petals, or petaloids (take Longhorn Pride, for instance, a Rosalind child that appears as a single but has lots of extra petals). 

I have only found one exception to my theory so far.  This is Aztec Treasure, whose parents are Montserrat and Jayella.  I have a couple of ideas as to why this might be. 

idea #1--- Although Montserrat and Jayella both appear to be singles, Monsterrat does have a double blooming grandparent (Sunburnt Sally).  Maybe the penetrance of the double gene in this family is low, as Sunburnt Sally only shows petaliods and Evelyn Howard (pollen parent of Montserrat, child of Sunburnt Sally) has a little bit of a ruffly texture.  Maybe ruffly texture has something to do with the double gene?  Montserrat is extremely ruffly.  Who knows?


idea #2--- Genetic mutation, plain and simple.







Thoughts...?

[helixturnhelix]

Interesting idea Jordan.

Sadly, I dont have much time to read and respond to these posts anymore, but it is possible that penetrance is the reason for variation in number of petals, etc. 

However, it is entirely possible that this is due to epigenetics, which are changes in gene expression due to environmental induction.  This differs from your idea of penetrance in that it is not one gene that makes a flower a double or single, but rather a group of genes.  Furthermore, these genes can be expressed or repressed depending on environmental conditions, like temperature, water, nutrition.  It seems that this could be the reason why there is such variation in number of petals are development of petaloids under conditions in which these parameters are unstable.   

It is difficult to understand which of these ideas is correct, penetrence and epigentics are both difficult ideas to test, but i think that your idea of the penetrance of is entirely feasible.  An interesting idea that would be very hard to test, but cool to think about.

Thanks for sharing!

[Charlie]

Very cool, indeed. Thanks to both of you for sharing!

Unless I am forgetting something, the double flowers all started with Hibiscus rosa-sinensis, the double red that John Piper showed a photo of recently. It has never been found in the wild but is thought to have originated in southeast Asia - China, India, or maybe Vietnam. It was then crossed with single flowered species found off the east coast of Africa and much later with the single flowered species species found in Hawaii and Fiji. Many of the crosses made after the 18th century were between hybrid varieties of the above species.

Charlie

[helixturnhelix]

Hi Charlie,

I think that this trait had to have been introduce by H. rosa-sinensis too.  The variability in these new hybrids depending on temperature. nutrition, water, etc... Makes me think that this trait is regulated by some sort of inducible set of genes.  Its pretty interesting overall, in fact I am curious if you know how often you have double offpsring from two singles, or if you ever get offspring from a cross like that. 

[Cindy]

I can't say how often it happens but getting a double from 2 singles does happen. I can't check my records until I get my computer back from the shop to find examples but this is known to occur.

Charlie

[Darkhorse]

Hmm, I'm curious to find out how often that does happen.  On that note I should revise my theory.  It must be correct that a number of genes control double vs. single of a hib flower, something like what controls human skin color.  Chris I definitely agree with you about the epigenetics too.  Environmental factors seem to control almost everything about a hibiscus flower!

[Charlie]

Happily, I am getting my iMac back today. I'm pretty pleased with the Apple Store in that they first told me a circuit board would have to be replaced for about $600. I would have bought a new computer before going that route but I had not backed up my data for months and could not afford to lose some of it so said, go ahead and fix it. Then yesterday they called back and said it was only the power supply that needed replacing and the charge was less than $100. All in all, a nice experience. I also bought a new backup drive from Apple which will make the 4th attempt to get something to work reliably for backing up.

Sorry for the preamble, I only meant to say I will soon be able to check my own results for singles that made double flowered varieties. It's not too surprising when you consider that one double flowered species was crossed with half a dozen single flowered varieties to give us the ancestors of today's hybrids.

Charlie

[Nievesgirl]

I can't wait too see the results from your computer I always wonder about this as well.

[Charlie]

Well, my old computer came back, worked for a few hours, then developed the same problem again. We decided to just order a new one since the old one was 5 years old and probably going to cause more problems. I don't have the new one yet, maybe today, and then will have to get the old one working well enough to transfer data over. Usually Macs are very reliable, so much so that you get lulled into thinking nothing will ever go wrong. The best thing about the new Macs is a new monitor technology. The previous display was far better than on any of my Windows computers but this new one is super bright and sharp.

Anyway, I will look into this when I get the data again.

Charlie

[Nievesgirl]

Someone on THML list has a great article about adding more K2O to get petaloids on single CV's.

I posted and shared my HBH with petaloids and gator pride with petaloids.

I think they where caused by the HVH booster I used with the HVH special blend.  I only used Bart's formula once and this seemed to make the hibiscus have more intensed colors also.