Orchid Parentage/Reproduction/Genetics

[JenHowlett]

Okay, so this is more a general question than a specific one.

Say a breeder crosses Phal X with Phal Y to produce "children" Z1, Z2, Z3...and so on. To avoid any confusion, obviously, X, Y, and Z in this case are simply variables- you can insert any specific species/hybrid you choose. Lets assume that the "children" of Phal X and Phal Z are diploid like their parents (yes, I know that plants, orchids included can be diploid, triploid and so on, but not all are and for argument's sake, we'll just assume that they are in fact diploid).

Think of it like two human children born of the same parents- their DNA is a product of the DNA from the parents, but because crossover and recombination at the molecular level is more or less random, the same two sets of parental DNA produce two different sets of offspring DNA. The kids may look similar and have the same parents, but they have their own unique DNA sequence and are not identical.

Obviously there are physical and chromosomal differences between plant sex and animal sex but at the molecular level it all pretty much functions the same.

Now here's my question: Will hybrid Z1 be identical to Z2 and Z3, or will it look almost alike but not quite? Remember these are seedlings produced from the pairing of the same two plants, Phal X and Phal Y, though a result of seperate flowerings and different seedpods.

For those who are wondering, I ask this question because I've seen internet pictures of several orchids, labeled as the same hybrid. They do look quite similar but under close examination one can discern subtle differences (such as the distribution of one or another color) that cannot be attributed to such things as photo angle, lighting, etc. Is one or more of the plants actually a similar looking (but different) hybrid and somebody misidentified it or are they really the children of the same parents (thus the same hybrid) who look slightly different?

[slipperfreak]

Z1, Z2, Z3, etc. are the same hybrid (or species) but are different cultivars - there is always genetic variation amongst the offspring of an event of sexual reproduction. Therefore yes, there are subtle differences between them. Essentially, propagation works like this:

Asexual reproduction = no genetic variation; offspring genetically identical to parent

Sexual reproduction = genetic variation; offspring inherit traits from both parents

[JenHowlett]

Originally Posted by slipperfreak

Z1, Z2, Z3, etc. are the same hybrid (or species) but are different cultivars - there is always genetic variation amongst the offspring of an event of sexual reproduction. Therefore yes, there are subtle differences between them. Essentially, propagation works like this:

Asexual reproduction = no genetic variation; offspring genetically identical to parent

Sexual reproduction = genetic variation; offspring inherit traits from both parents

Obviously, yes, there has to be genetic variation in any form of sexual reproduction. However, are such differences discernable to the naked eye (i.e. do the orchid flowers look slightly different) or is the genetic variation more subtle and discernable only through molecular testing?

[slipperfreak]

Originally Posted by JenHowlett

Obviously, yes, there has to be genetic variation in any form of sexual reproduction. However, are such differences discernable to the naked eye (i.e. do the orchid flowers look slightly different) or is the genetic variation more subtle and discernable only through molecular testing?

It depends on how observant you are. Technically yes, they are discernable to the naked eye. That's why some cultivars of a given species or hybrid get flower quality awards and some don't. If you're a "picky" person, you can see the differences. Many people, however, don't.

[cabnc]

Yes, the genetic variations are discernible to the naked eye. In the past, the few seedlings that survived and flowered AND were awarded (ie, judges chose them to have desireable characteristics) were very expensive, they were one of a kind.
Today, that awarded hybrid is cloned, and everyone can own an awarded hybrid.

Charlie

[Ray]

Sometimes the differences can be subtle, and at other times less so. Here are two cymbidiums from the same capsule, for example:

Then, unlike animal sexual reproduction, things can get more complex when you swap the parental roles of the two blossoms.

[cb977]

Interesting thread!

[trdyl]

Nice discussion.

[slipperfreak]

Nice example Ray. Some crosses can definitely be extremely variable.

[Royal]

Hi Jen,

Sounds like you got your answer. Just to add to the discussion, some species/hybrids breed rather predictably and others vary wildly. The way orchid cultivars are identified is with single quotes, usually when they will be bred further and need to be indentified so you know which Z was used in a particular cross.

X x Y = Z All of the Z's may look very similar, but a few may stand out. You (the grower) may decide that certain offspring are exceptional and decide to assign cultivar epithets. You may have:

Z 'Jumbo'
Z 'Pink'
Z 'Stripes'

All the rest may be junk and need composting, or they may be nice but just not worthy of breeding on. If Z 'Jumbo' is award quality and it gets cloned vegetatively, all of these clones would carry the 'Jumbo' cultivar epithet as they would be genetically identical.