1N, 2N, 3N, 4N What is meant by these designations when seen on a plant's tag?
I've most recently seen it (4N) on a phragmipedium given to me. Thank you.
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Jenkins,
Onesy, twosy, threesy, foursy-ploid. Or, as Latin and "proper" orchid people say singular, diploid, triploid, tetraploid. Most orchid people like tetraploid orchids (for show) and pay big money for them. "Tetras" (4N) have four times the haploid number of chromosomes inside the cell nucleus. Bis, Tris, and Tetras often look more husky and robust... sometimes the flowers are bigger, the leaves feel more leathery and thicker (esp Cattleyas). Many times these plants will not be good breeders however and can be a shooting star (ie mules) as their breeding line dies out with that plant... unless you can clone it. Mick HBI, Producers of Fine Orchids in Flask www.OrchidFlask.com ================================== wrote in message . .. I've most recently seen it (4N) on a phragmipedium given to me. Thank you. |
Ploidy refers to how many sets of chromosomes a cell nucleus contains.
Usually, every cell has two copies of a chromosome, and is designated 2N. Usually, higher ploidy number means more robust plant (sequoiae are 6N and are huge trees, and some of the most robust)- if some genes get damaged, they have more backup genes to work with. However, a 3N plant can only produce progeny with a 3N plant, and 4N plants, preferably with other 4N plants. Cheers, Xi wrote: I've most recently seen it (4N) on a phragmipedium given to me. Thank you. |
Very rarely, if ever, will a 3N X 3N produce any off spring. In orchid
breeding I have learned to never say never. Instead, 3N are most often crossed with 2N with the hope that the 3N will produce a few unreduced gametes (6N pollen or ovule). This type of cross is in fact looking for a 6N X 2N (or 2N X 6N) mating producing 4N offspring. When flasking a crossing like this, you hope for a couple of viable plants out of a pod. In my experience, most times the cross will not take . . . but it could happen. Most 4N Phrags can be traced back to the Eric Young Foundation. The foundation converted 2N besseae (and other phrag species) to 4N using colchicine. The various 4N phrags were then crossed to produce some stunning 4N hybrids. The Foundation sold a lot of 4N besseae hybrid flasks a while back (Baltimore EOC timeframe). We are now seeing what came out of those flasks as well as the next generation of hybrids on the market. They seem to plentiful, inexpensive, and very high quality this year. Pat "Xi Wang" wrote in message news:Ujt0e.767329$6l.713106@pd7tw2no... Ploidy refers to how many sets of chromosomes a cell nucleus contains. Usually, every cell has two copies of a chromosome, and is designated 2N. Usually, higher ploidy number means more robust plant (sequoiae are 6N and are huge trees, and some of the most robust)- if some genes get damaged, they have more backup genes to work with. However, a 3N plant can only produce progeny with a 3N plant, and 4N plants, preferably with other 4N plants. Cheers, Xi wrote: I've most recently seen it (4N) on a phragmipedium given to me. Thank you. |
"Mick Fournier" wrote in message ...
Jenkins, Onesy, twosy, threesy, foursy-ploid. Or, as Latin and "proper" orchid people say singular, diploid, triploid, tetraploid. 1N would be "haploid," not "singular." Bis, Tris, and Tetras often look more husky and robust... sometimes the flowers are bigger, the leaves feel more leathery and thicker (esp Cattleyas). "Bis" (i.e. diploid) are typically the normal, wild type plants with one pair of each chromosome. Haploidy will only be found in pollen and egg cells. Many times these plants will not be good breeders however and can be a shooting star (ie mules) as their breeding line dies out with that plant... unless you can clone it. Tetraploids should be fully fertile with other tetraploids of the same species. When crossed to diploid plants, you will get sterile or semi-sterile triploids. IIRC, H&R nurseries has a habit of breeding 4N to 2N in their cattleya seedlings. I'm not sure if this is a deliberate strategy for generating attractive but sterile plants. Nick |
Xi Wang wrote:
Ploidy refers to how many sets of chromosomes a cell nucleus contains. Usually, every cell has two copies of a chromosome, and is designated 2N. Usually, higher ploidy number means more robust plant (sequoiae are 6N and are huge trees, and some of the most robust)- if some genes get damaged, they have more backup genes to work with. However, a 3N plant can only produce progeny with a 3N plant, and 4N plants, preferably with other 4N plants. 3N plants (triploids) are notoriously infertile. Regardless of what you cross them with. Even ploidy (2,4... etc) are more fertile because they can properly pair off chromosomes during meiosis. Rob -- Rob's Rules: http://littlefrogfarm.com 1) There is always room for one more orchid 2) There is always room for two more orchids 2a) See rule 1 3) When one has insufficient credit to obtain more orchids, obtain more credit |
A big thank-you to all of you who responded with such succinct info re
'ploidy'. I've had quite a bit of experience, genetically, with certain mutations of the gouldian finch (Chloeiba gouldiae), but never had to wonder if any progeny were a 'grex' or whether their chromosome pairing/distribution represented genotypic 'mules'. Alleles and loci seem pretty mild compared to orchid pollen! Thanks again. |
Hi,
Thanks for the info, that's news to me, and I guess I'll have to do some reading. I knew that 3N was bad for breeding because if you cross a 3N with a 2N/4N, you get an aneuploid. But I still thought that most of the time, the gametes would be okay. During meiosis one, there is chromosome doubling and one reduction, and then another reduction in meiosis II, what is it about 3N that makes the second reduction difficult? If a nucleus had just one chromosome, during metaphase 1, it would pair up with it's copy and separate, and then in metaphse 2, there is no pairing required, but merely separation of the tetrad....right? Cheers, Xi Rob Halgren wrote: Xi Wang wrote: Ploidy refers to how many sets of chromosomes a cell nucleus contains. Usually, every cell has two copies of a chromosome, and is designated 2N. Usually, higher ploidy number means more robust plant (sequoiae are 6N and are huge trees, and some of the most robust)- if some genes get damaged, they have more backup genes to work with. However, a 3N plant can only produce progeny with a 3N plant, and 4N plants, preferably with other 4N plants. 3N plants (triploids) are notoriously infertile. Regardless of what you cross them with. Even ploidy (2,4... etc) are more fertile because they can properly pair off chromosomes during meiosis. Rob |
Myrmecodia,
That's some right fine scientifical talk there... but down here in Florida I just know that when any orchid seller starts talking that ploidy stuff... I tighten up my butt cheeks and run south cause the next thing to follow means some orchid buyer (in close proximity to the seller) is going to get a good "greasing" and a follow-up screwing price-wise on that fancy ploid plant paying di-as-much, tri-as-much or tetra-as-much as it should have cost.... and, I don't want it to me. Mick PS, now I am going to go Imploid. |
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