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Old 24-03-2005, 02:48 AM
 
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Default 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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Old 24-03-2005, 03:56 AM
Mick Fournier
 
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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.




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Old 24-03-2005, 07:43 AM
Xi Wang
 
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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.


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Old 24-03-2005, 01:27 PM
Pat Brennan
 
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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:[email protected]
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.



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Old 24-03-2005, 02:55 PM
Myrmecodia
 
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"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


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Old 24-03-2005, 03:48 PM
Rob Halgren
 
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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

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Old 25-03-2005, 12:32 AM
 
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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.


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Old 25-03-2005, 02:40 AM
Xi Wang
 
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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


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Old 25-03-2005, 03:57 AM
Mick Fournier
 
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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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