The red tube phenotype

[john]

At the end of 2006 I bought some seed from Aidan of the hybrids he made that year. A number of the hybrids had S.flava rubricorpora in the parentage and it has given some interesting information on the way the red tube characteristic is inherited.
The first hybrid was Sarracenia flava atropurpurea SF-84-AS from Apalachicola National Forest x Sarracenia flava 'Claret' SF-15-AS (one of Adrian Slack's original clones).
The picture shows four seedlings.

Both of the parents are good red tubed plants, the seedlings split between red tubed and green tubed plants without intermediates. The only interpretation I can put on this is that "red tubed" is inherited as a single dominant characteristic, and that both of the parent clones are heterozygous for the gene.

The second hybrid is Sarracenia flava rubricorpora SF-13-AS, Apalachicola National Forest x S.flava rubricorpora SF-46-AS, Sumatra, Florida.

These all seem to be red tubes. The colour is rather pale because the seedling beds are rather shaded - I am expecting them to be much darker this year.
The implication is that at least one of the parents is homozygous for "red tube". It may just be a matter of chance that there are no green tubed plants among the seedlings, and I am interested in how other hybrids using the parent clones will develop, but my initial assumption is that one of the parents (at least) is homozygous.

The third hybrid is S.flava rubricorpora, SF-91-AS ex Don Schnell x S.oreophila SO-10-AS.

I am interpreting all of the seedlings as red tubed. They have been shaded up to this year, and I think next summer they will be very much deeper in colour. The S.oreophila parent is just a run-of-the-mill plant which presumably carries no "red tube" gene, so the colour in these hybrids is all inherited from the other parent, which is presumably homozygous for "red tube", and as such a good plant if you are interested in breeding red tubed plants - all of its offspring in the first generation will have red tubes.

I am interested in hearing any other interpretations of the results?

And now the controversial bit ... If the "rubricorpora" phenotype is the consequence of a single dominant gene there is little justification for maintaining the plant at varietal level, and it should be demoted in rank to forma. Sarracenia flava f. rubricorpora.

(light blue touchpaper and...)
What do other people think?

[theinactivemoth]

I think they look nice...

[meadowview]

Hi John:

This is something we have been working on for a long time with our controlled crosses but have not published. Yes, intense red pigmentation appears to be (is) a homozygous dominant allele. Furthermore, and we can demonstrate this in our data, the pure red phenotype in S. flava comes from a dominant homozygous allele in S. PURPUREA!! In other words, what we are seeing are introgressed plants with another species. Don't be frightened by this folks since this is a natural process. Folks seems to seek "pure" but nature is not behaving this way with Sarracenia and it is more than likely a very important part of the evolutionary process.

As we gain a greater understanding of the genetic basis of these S. flava phenotypes the designation of form may be most appropriate.

Sincerely,

Phil Sheridan, Ph.D.
Director
Meadowview Biological
Research Station

[Aidan]

Feb 2, 2011 15:56:31 GMT meadowview said:

Don't be frightened by this folks...

Just goes to show that there really is only one species of Sarracenia

[Dave Evans]

Dear Phil,

I have long believed that the red color seen in S. flava comes from S. purpurea since the coloration patterns are the same. Almost like a finger print.

Of course, there is no S. purpurea in the southern end of the range for S. flava, but it is replaced by S. rosea and again, there are different "red color patterns" in the southern populations of S. flava, which again match the patterns seen S. rosea.

I know you're joking Aidan, but some people get really confused about the differences between hybrids and species. I think they might be misapplying animal breeding patterns to plants or something along those lines...

[Alexis]

I suspect 'Claret' is an intraspecies hybrid. Something like rubricorpora x flava.

[John Brittnacher]

Feb 2, 2011 15:56:31 GMT meadowview said:

This is something we have been working on for a long time with our controlled crosses but have not published. Yes, intense red pigmentation appears to be (is) a homozygous dominant allele.

Phil:

Can you define what you mean by "homozygous dominant". Do you mean recessive?

[john]

Hi Phil, thanks for the information (hope I haven't trodden on any research toes). Look forward to seeing your work when you publish.

Interesting that the gene derives from S.purpurea I have been trying to get my head around the range of heritable characters there. Interesting that the red tube colour has persisted but the colour has been eliminated again from the flower - there must be a strong selection pressure for yellow flowers at work.

[Alexis]

I'm sure it would be possible to test yellow vs. red flowers. Sometimes stands of rubra ssp. wherryi have both colour types. I wonder which are more successful?

[meadowview]

Hi John B:

I meant to say that the red allele is simply dominant (which means if the gene is homozygous or heterozygous for that allele you will see the trait). If you just have one big A allele, as in Aa, you will get strong red pigmentation throughout the pitcher. An example of this is actually two of the crosses we sell. We crossed Powhatan (pure red S. flava) with S. jonesii green (anthocyanin-free) and the result in the first generation is Red Viper (pure red) and Black and Tan (normally pigmented Sarracenia). This is an excellent demonstration that heterozygous Powhatan (Aa) crossed with S. jonesii green (aa) resulted in a test cross F1 outcome of 50:50 Aa (red Viper) and aa (Black and Tan). We've got several other crosses into F2 generation involving S. flava and S. purpurea which very clearly show the movement of the big A allele and intense red pigment. Now, John was talking about red tubes which may be a somewhat different or modified situation compared to our pure red S. flava but the mode of inheritance is likely similar (as demonstrated by his results)

No problem John you're not stepping on our toes. These are exactly the kinds of controlled crosses that need to be done by multiple researchers to figure out Sarracenia genetics. I have to tell you that Sarracenia are NOT the model organism to study genetic traits because they are relatively slow growing and there can be inbreeding and loss of seedlings (fruit flies or Arabidopsis have a lot of merit in resolving as model organisms in genetics). All of this means it takes a while to get the plants where you can score them, and even then, you may not have enough plants to assess phenotype inheritance. We've had to repeat experiments several times and still don't have enough progeny to score phenotypes (a long drawn out Ph.D. program didn't help matters). We're into some of our experiments at the ten year mark and I now have to start thinking of my mortality and whether we'll get the answers before I move on!

Best,

Phil

[john]

Thanks for that, Phil. Don't even mention inbreeding to me - I am currently bogged down in the seed data statistics for this year. Spent all day yesterday wrestling with it, and discovered I had "demonstrated" that black was white. Threw the whole lot in the bin and will come back to it when I am a bit more clear headed lol.
Interested in your comments about all red flava. Seems to me we have two quite different genes or gene complexes producing similar phenotypes that we lump as atropurpurea (I'm starting to think that is a meaningless taxon). The first is simply rubricorpora where the green on the lid is reduced to nothing (probably the action of a cumulative polygene). The second produces red colour evenly across the top of the pitcher, sometimes extending to the base of the tube, but usually fading out about half way down (in some ways analagous to cuprea but with red/purple anthocyanin instead of copper). Only recognised the second pattern quite recently and haven't tried raising seed from it yet. Sorry, that's a bit rambling. Two questions, how do you interpret the phenotype "atropurpurea" and is cuprea the expression of a variant anthocyanin - are there 'copper' red tubes, for example, or 'copper' rugelii? I've not seen them in Europe, but that's not the same as looking through wild populations, Certainly there seem to be a few copper and orange tubed hybrids appearing at the moment.

[PHaze]

Feb 2, 2011 15:56:31 GMT meadowview said:

Furthermore, and we can demonstrate this in our data, the pure red phenotype in S. flava comes from a dominant homozygous allele in S. PURPUREA!! In other words, what we are seeing are introgressed plants with another species.

Wow, that is really interesting. I would love to hear about how you were able to determine that S. flava's red originated in S. purpurea. If you would prefer not to share the details before your work has been published, I can certainly understand.

I really admire your patience and persistence in performing such long running studies.

[John Brittnacher]

Feb 5, 2011 16:22:03 GMT meadowview said:

We crossed Powhatan (pure red S. flava) with S. jonesii green (anthocyanin-free) and the result in the first generation is Red Viper (pure red) and Black and Tan (normally pigmented Sarracenia). This is an excellent demonstration that heterozygous Powhatan (Aa) crossed with S. jonesii green (aa) resulted in a test cross F1 outcome of 50:50 Aa (red Viper) and aa (Black and Tan).

What are the odds that the anthocyanin-free mutation is in the same gene that causes S. flava red? I would think it is rather small so your cross is multifactorial. This would mean you don't really know the background for the S. jonesii at the red locus (presuming there is just one locus) because it is hidden by the lack of anthocyanin. Of course with S. jonesii, red tube pattern doesn't exist naturally but the plant could be heterozygous for the gene that causes red S. jonesii.

I wonder if the red S. jonesii allele is the same one as the one that causes black S. alata because my red S. jonesii are almost black or at least dark brown whereas the red S. flava are just red. It would be interesting if the black S. alata is really the same as the red S. jonesii and if they are the same as any of the reds in S. flava. But as you said life is too short to do this via crosses although intercrossing the red/black versions by each other might prove interesting. And DNA sequencing is still a little pricy presuming you even know where to look in the genome.

[Brian Barnes]

Excellent topic gentlemen!

I've been following the thread with great interest. Also, we should have some interesting results coming soon from an ICPS funded Sarracenia genetics study at University of S. Alabama. Having studied the same anomalies of said topic in the field for quite some time, I have run across the instances spoken of here on many occasions. Take for instance at this well-known site of Sarracenia flava var. atropurpurea. One can many specimens that almost seem "stuck" in between the heavily-veined forms and the all red forms somewhat. Also, one will see the plants that are completely blood-red including the lid mixed throughout the colony.



Plus, I've encountered the same genetic mutations or lack thereof at Splinter Hill Reserve and other Sarracenia leucophylla sites throughout the southeast US as well. Even in areas with no interspecies contact for miles.



I've always entertained the hypothesis that there are no pure species except maybe for a few stands of Sarracenia minor that exist over 300 miles from any other species and this is also based on the drastic differences in appearance....but that's just my humble penny's worth.

Happy Growing,

Brian

[Sockhom]

What a fascinating thread. Brian, these two last pictures are killing me. (I know I bring nothing to the topic, sorry... ;-)

François.