Orchid Parentage/Reproduction/Genetics

[Cym Ladye]

Jen,

Ray almost said it all with the two photos. A picture is definitely worth a thousand words!

I will add further that the offspring of the same two parents may also have different ploidy allowing some easier to breed and some not so. I think primarily of the original, very successful Cymbidium cross of (Fifi x parishii) which resulted in a known 2n, a known 4n and a majority of 3n, some capable of breeding. I do not know which of the parents was triploid but one was. The cross was later remade using both tetraploid parents.

CL

[Royal]

Originally Posted by Cym Ladye

Jen,

Ray almost said it all with the two photos. A picture is definitely worth a thousand words!

I will add further that the offspring of the same two parents may also have different ploidy allowing some easier to breed and some not so. I think primarily of the original, very successful Cymbidium cross of (Fifi x parishii) which resulted in a known 2n, a known 4n and a majority of 3n, some capable of breeding. I do not know which of the parents was triploid but one was. The cross was later remade using both tetraploid parents.

CL

Triploid pollen is infertile, so the 3n would have to be the capsule parent. Species are almost always diploid, so Fifi must have been tetraploid. Crossing a 4n and a 2n is generally not a good thing. It was a good idea to re-make it with two tetraploids.

While it is true that when you are using parents with dissimilar numbers of chromosomes, the progeny will have ploidy issues but may create a few chance 2n or 4n offspring. But two diploid parents will produce all diploid offspring, and tetraploid parents yield all tetraploid offspring. Of course there are exceptions, chance mutations. But this is probably closer to one in a million than one in a hundred.

In my opinion, triploids should be avoided in breeding all together and only make problems worse. Just my .

[slipperfreak]

I'm wondering what exactly the advantage of breeding triploids is. You see quite a few 3n Phrags, particularly in besseae breeding. In Phrags, 4n crosses tend to be superior to 2n in every way. However, they can sometimes get "teeth" on the sepals and petals. Does anyone know if this occurence is reduced in 3n? What other advantages would there be when 3n are sterile?

[Royal]

There is no advantage. Triploids are breeding dead-ends. If your goal is to sell potted plants by the thousands and without labels, who cares if they're sterile?

Triploids can be fertile as the capsule parent. Tetraploid pollen on a triploid flower could result in some tetraploids, but not as often as one would think. There are some great 3n hybrids out there that people shell out lots of cash for, also many are "claimed" to be 4n but really aren't. Some growers refuse to concede that their prized plant is a genetic abomination and shouldn't be used in breeding. This only perpetuates the use and creation of aneuploids.

[Connie Star]

Fascinating thread. But how do you know if a plant is diploid, triploid or tetraploid? Does someone do karyotyping of the orchids, or is it just assumed somehow? Are there any haploid specimens, or any who are higher than 4N? Also, are there any mosaics with some cells 3n and some cells 4N on the same plant? I would love to be in a lab where they study this!

[slipperfreak]

Originally Posted by Connie Star

Fascinating thread. But how do you know if a plant is diploid, triploid or tetraploid? Does someone do karyotyping of the orchids, or is it just assumed somehow? Are there any haploid specimens, or any who are higher than 4N? Also, are there any mosaics with some cells 3n and some cells 4N on the same plant? I would love to be in a lab where they study this!

You don't really know for sure the ploidy of a plant without confirmation from the vendor (or without taking a sample to a lab), but you can usually tell if a plant is 3n or 4n because the flowers are larger, have better shape, and better color than their 2n counterparts.

I don't know of any haploid orchids. Someone please correct me if I'm wrong, but I don't think haploid angiosperms are possible because one set of chromosomes comes from each parent. I don't know of any occurences of mosaics either, or plants with more than 4 sets of chromosomes.

[ronaldhanko]

Great thread! Here's another example of three cultivars from the same cross:

[ronaldhanko]

Great thread! Here's another example of three cultivars from the same cross:

[cabnc]

From info gathered from phal hybridizers, only ploidy confirmation from a lab is reliable. There is mapping being done of the ploidy of phal hybrids to determine which are 2N, 3N or 4N. To determine which hybrids should then be used in future breeding. The theory that flower / leaf / root size, shape, color is a reliable marker has been proven to be very unreliable.

Charlie

[camille1585]

To get back to the original post, Z1, Z2 and Z3 can be perfectly identical to each other if the parent plants are both completely homozygous. Homozygous is when both alleles of a gene are the same, either both dominant or recessive. Homozygote = AABBCC and heterozygote would be AaBbCc for example.

I really don't know if this is the case in orchids, but in many crop plants, pure lines (homozygotes) are made by taking haploid gamete cells and treating them with colchicine to double it and obtain a diploid. Since you are doubling the single allele, you'll get homozygote diploids.

When you breed two different homozygotes, such as AABB x AABB, all offspring will be AABB. If you breed AABB x aabb, offspring are all AaBb.

But I don't know if many pure lines have been created in orchid breeding by the breeders, and if they have, they are more likely to be used as breeding stock rather than propagated and sold. Also, the fact that all orchids are cloned for mass production eliminates the need for the sexual production of identical offspring.