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Sporting back to a species

Posted by brianmkerr S/CoastQLD Aust (My Page) on
Sun, Feb 27, 05 at 22:38

Hello Everyone, Don't know if this topic is appropriate for this site, but was wondering if anyone has an opinion on whether or not a Hibiscus Variety known as Snowflake could possibly sport back to a species called Schizopetalus.

A friend of mine has shown me exactly this. I have checked for where the sport is and it is growing well above the flowering Snowflake.

Regards from a mystified Brian Kerr.


Follow-Up Postings:

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RE: Sporting back to a species

Brian,

It looks like 'Snowflake' (and 'Roseflake') is just a variegated version. So, the reversion is just the loss of variegation. Are the flowers the same?

Loss of variegation is not unusual.

Karl


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RE: Sporting back to a species

Hello Karl, Thanks for your reply.
Bloom on 'sport' is exactly the same as the original species, not at all like Snowflake, other than both being red.
Knowing enough about traits passed down to Schizopetalus seedlings, I can say with reasonable certainity that Schizopetalus would be a parent of Snowflake, most likely the father.
Re loss of variegation, Snowflake does do this, but the bloom on the resulting 'green' leaf version of Snowflake, is almost exactly the same as Snowflake. The green leaf version is at the moment being investigated to see if is the same as what we know as either Andersonii or Archerii.

Thanks again for your reply.

Regards, Brian Kerr.


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RE: Sporting back to a species

Brian,

It is sometimes found that an F1 hybrid may express "pure" parental traits as mosaics -- the seed parent trait in some tissues, the corresponding pollen parent trait in adjacent tissues.

For example, some blackberry-raspberry hybrids produce some fruit that are firmly attached to the core (like blackberries), some loose (like raspberries) and others that are partially attached (the "hybrid" condition). If the parents differ in trichomes or stomata, the parental types may segregate in adjacent tissues.

Charles Naudin, the French hybridist, studied and wrote about this phenomenon in the 19th century, but Mendel -- who read Naudin's papers -- did not see it in his pea experiments. Or at least he did not discuss it.

So, it is possible that your sport is of this type -- somatic segregation.

Somatic segregation seems to include at least two distinct phenomena. One type may involve changes in gene activation. That is, a gene or chromosome segment is silenced in one parent, while the corresponding region is active in the other. If the silencing is copied to the active partner, the "sport" or mosaic region will tend to resemble the parent with the silenced segment. But if unsilencing is copied, the expressed trait will tend to resemble that of the other parent.

The second type involves physical segregation resulting from somatic meiosis -- with or without spindle formation. Crudely stated, a cell may double its chromosomes in anticipation of mitosis, then "forget" to divide. If the cell was originally diploid, it will now be tetraploid and may continue as such for a mitosis or two. Then, it (or they) can "remember" and do an extra cell division to bring the chromosome number back to normal. Just like meiosis.

I have an old report on this type of somatic segregation on a rabbit.

It is possible to stimulate somatic segregation by feeding cells unpolymerized deoxyribonucleic acids or caffeine (which is easier to acquire). Apparently the cells are tricked by the free DNA (or caffeine) into "thinking" that chromosome duplication has already occurred, and slipping an extra cell division into their cycle. The haploid cells may then correct themselves by skipping the next cell division, which brings them back to their normal diploid condition.

Here's a link to an article on caffeine and somatic meiosis in Arabidopsis thaliana.

I think the caffeine trick should be used on sterile hybrids to obtain segregation without relying on flower formation.

Caffeine could be introduced via an IV drip, if you can get the needle into the cambium. Or you might try Michurin's layering tube.

Karl

Here is a link that might be useful: Mosaic Rabbit


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RE: Sporting back to a species

Hello Karl, Thanks so much for your information. It will be great to work on this new direction - lots of irons in fire !

Thanks again. I appreciate your input.
Regards, Brian Kerr. For your interest, I'll attach a web site with some of my hybrids.

Here is a link that might be useful: Brian Kerr's Hybrids


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