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Alba breeding questions.....

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Marco

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If an alba is selfed will that necessarily mean that the offspring will be alba?

If if an alba is sib crossed with another alba which originally came from a self will the probability of having alba offspring increase in subsequent sib crossings of the alba offsprings? i.e. greater in 4th and even greater in 5th generation breeding

Does the probability depend on the species?
 

Candace

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Are you thinking about breeding anything in particular? If it's a micranthum alba you'll be the man of my dreams:>
 

Marco

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sorry i don't own any micranthum album :( Id probably just kill em. Your prince charming is holding onto that paph climbing gold locks somewhere you just have to keep looking. :poke:

I was just wondering about alba flasks that are sold. How can a vendor be sure that the plants will bloom alba?
 
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Eric Muehlbauer

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Most vendors will be honest about the likelihood of getting albas from a cross. In most cases, an alba selfing should produce all alba plants, but I am not an expert on paph genetics. However, most descriptions of album paph crosses only mention a likelihood of albas, rather than a certainty. In many cases, the album is crossed with a non-album, and so far, every description I have read has honestly said that the offspring would not be alba, but could be used for album breeding. Take care, Eric.
 
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gore42

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Marco,

In the most simple, Mendelian terms, albinism is typically a recessive trait (assuming that it's a simple trait). That means that if the plant is expressing albinisms, both alleles are the same (homozygous recessive), and since only recessive alleles are present, the parent can only pass on the recessive condition to its offspring.

Like so: P = dominant allele for pigmentation, p = recessive allele (no pigment)

PP = expresses pigment
Pp = expresses pigment (since P is dominant)
pp = no pigment

So, if the pp is selfed, it can't possibly pass on a P.

Obviously, that's a gross over-simplification, considering the possibility of co-dominance, multi-locus traits, etc, but it works most of the time.

- Matt
 
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paphiness

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selfing of an alba

I have an extensive article series on my website that discusses basic orchid genetics, and uses exactly this very issue of alba's as an example. You can check it out here:

http://www.paphinessorchids.com/index.php?option=com_content&task=view&id=22&Itemid=63

But just to be explicit, consider that you have a micranthum var. alba which has "aa" as its color genotype, where "a" is recessive to the "A" allele, found in normal color micranthums.

If you selfed "aa" -- in other words, you did the following:

aa x aa

...you could ONLY get "aa" as a resulting genotype, which means that you could only get album plants.

If you sib crossed your "aa" plant with ANOTHER "aa" plant, the above situation would repeat itself (as long as we are discussing only that gene on both copies of the chromosome):

aa x aa

So, if a vendor claims that a flask WILL be ALL alba, it must mean that both parents are confirmed alba plants. Whether you believe the vendor's knowledge of genetics or honesty is another issue...

If you cross a known alba with a normal color plant that carries a recessive alba allele, you'd get a cross like this:

aa (known alba) x Aa (carries normal color allele "A" and recessive color allele "a")

and 50% of the plants would be alba (in theory).

If you cross a known alba with a normal color parent that does NOT carry any recessive color allele, then you'd get a cross like this:

aa (known alba) x AA

and 100% of your plants would flower out the normal color form, but carry the recessive "a" allele, giving the POTENTIAL in the next generation of albas, depending on the genetic composition of the other parent.

Have trouble with terms like "recessive", "dominant", and "alleles"? (Don't worry -- some vendors do, too.) They are all painstakingly defined and illustrated at the aforementioned article on the Paphiness Orchids site. Feel free to email me directly with questions as well...
 

Roy

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Marco, if you have a read through the Taxonomy section, Puzzler ,there is a transcript I placed there from Olaf Gruss. Basically, a selfing of an alba / albino
flower ( Paph ), there is definitely no guarantee that all seedlings will be alba / albino. All you can do is grow as many as you can to flowering and see what happens.
 

ScottMcC

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marco, the answers to your questions are no, yes, no.

but to expand, flower color, like most other aspects of phenotype, is not monogenic, nor is it inherited in a purely Mendelian fashion. this leads to occasional frustrations for breeders, as efforts to make an aesthetic, desirable cross from 2 strong parents will sometimes meet with failure (depending on who you ask, the likelihood of this occuring varies :p ). to use an example along my previous lines, this would be paph roth 'awesome-o' x paph roth 'even better' = paph roth 'uggo.'

as for the reasons why this occurs, part of it is not fully understood, and the rest has to do with the fact that genetics is far, far more complicated than Mendel realized. for an example of the above, watch that show on the Learning channel about the family with dwarfism--while both parents are achondroplasts, and some of the children are, not all are, despite the fact that this is a supposedly recessive trait.

as for the effect of line breeding in inducing heterogeneity, this is definitely true, for a simple reason. the first time you make a cross, they have distinct genetic contributions from the father and mother. for instance, paph roth 'awesome-o' x paph sanderianum 'rockin' = paph prince edward of york 'awesome rocker.' clearly evident will be a certain percentage of roth and a certain percentage of sanderianum. now if you self or sib 'awesome rocker,' you're going to get highly variable results, because each parent plant will contribute a varying amount of its respective parents' genes to the offspring. so one plant may be vary roth dominated, one may be very sanderianum dominated, and the majority will be somewhere in the middle, but won't necessarily look like prince edward of york. in the next generation, there will be less variability. over time, if you continue to self the offspring (especially if you selectively self those that fit the phenotype you desire), you will have completely homogeneous offspring. the analogy that I find most helpful for understanding this process is that of mixing a chocolate cake. the batter is first white, and then chocolate is poured in. initially, the contributions of the batter and the chocolate are readily apparent, and if you were to bake it without stirring, you'd get a half white, half chocolate cake. but if you were to gently stir that, you'd get some parts of the cake white, others chocolate, and the majority kinda muddy. over time, and with more stirring, the cake becomes smooth and even.

anyway, hopefully this is clear. If not, let me know and I'll try to clarify.

paphiness, I personally think that if a vendor can guarantee a flask is all alba, then they are at least one of the following: very confident, very deceptive, very ignorant, or a masterful scientist who has managed to mericlone a paph.
 

NYEric

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alba

All this science-sorcery heretical blaspheming is making my head spin!Go ahead and tell 'em what you got. Bill assured me that the plants all came true albas, this was the second selving of albas so they're pretty much sure to be alba, not 1/4 chance. :D
 
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paphiness

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monogenic vs. multigenic traits with respect to color

Good points by Scott McC.

In my post above, I was referring to a monogenic color trait. It is true, for example, that you can have two different genes defective in a color/pigment synthesis pathway, that when combined in one individual results in albinism. A selfing of such an individual could result in color progeny.

I should also qualify that I am referring only to species alba plants; it is well-known that when you deal with hybrids, all bets are off.

Of the paph species I've observed in long-term alba breeding programs, all have inherited in Mendelian fashion.
 

ohio-guy

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Correction

" for an example of the above, watch that show on the Learning channel about the family with dwarfism--while both parents are achondroplasts, and some of the children are, not all are, despite the fact that this is a supposedly recessive trait."

Actually, this is not correct.

The parents of the family on the learning channel have two different kinds of dwarfism. The mother has achondroplasia which is an autosomal dominant trait and as such there was a 50% chance for each of her children she could pass it on. As it happened, only one of her 4 children got the gene. The father has a recessive condition, which is unrelated. He must have two recessive genes to be affected. He passes the gene to each of his children, but since the mom is homozygous dominant, or has 2 'normal' genes, none of the children display the fathers type of dwarfism, even though each of them has a copy of the recessive gene from the father.

At this point each child now has one 'normal' gene from the mom, and one recessive gene from the dad, for his form of dwarfism.
And one of the kids ALSO has one dominant achondroplasia gene from the mom, the rest having gotten the unaffected gene from her.
So, what are the chances of any of the kids having children with the conditions of their parents? All three standard height kids carry the recessive gene for their fathers kind of dwarfism, which is rare in the general population, so it is unlikely they would have children with another carrier of the recessive trait. Also, unless they have a spontaneous mutation of the gene that causes achondroplasia, they cannot have a child with the kind of dwarfism their mother has. (It is true however, that the majority of people with achondroplasia get it from a spontaneous mutation)

The only child likely to have a child with dwarfism is the one with the single dominant gene for achondroplasia. he has a 50 -50 chance of passing the gene on.

Sorry for the lecture, but these are people with real problems, and it is good to understand it correctly.
 
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Eric Muehlbauer

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Another note about achondroplasia....its more than just a dominant gene...all people with achodroplastic dwarfism are heterozygous for the condition- one achondroplastic gene, one normal gene. In the homozygous (two identical genes) conditions, achondroplasia is lethal.....problems go beyond dwarfism to skull and brain abnormalities...I don't believe a homozygous individual can survive more than hours past birth....Take care, Eric
 

ScottMcC

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I stand corrected. I had remembered things wrong regarding achondroplasia, and reviewed the texts, and you're both right. however, the cause of death in homozygotes with achondroplasia is listed as thoracic constriction, not skull problems. however, the leading cause of death among young achondroplasts (at least, of those associated with the disease) is cervico-medullary compression, due to malformation of the bones of the skull base. of course, I find the development of the skull to be fascinating, and achondroplasia to be a good illustrator of this development, because the bones of the skull are formed from multiple different embryonic precursors, some of which dependent on cartilage and others not (membranous vs endochondral bone).

but back to the matter at hand, achondroplasia is a completely dominant trait, with 100% penetrance. therefore, if two achondroplasts have kids, you would expect that 2/3 of the surviving children would have achondroplasia, and the remaining 1/3 would be of normal stature (these numbers are based on 1/4 of the offspring being homozygotes and not surviving). but this is often not entirely the case, in that the non-achondroplastic children also have an increased rate of short stature. so again, something more than purely mendellian patterns must be at work.

and I managed to inadvertently make an even better example of the danger of using phenotype to imply genotype. to a casual observer, both of the parents on the learning channel show have a similar phenotype, yet apparently (and I was actually unaware of this because I haven't watched the show other than the commercials), they have different forms of dwarfism, and thus different genotypes.

so anyway, thanks for correcting my errors.
 
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Eric Muehlbauer

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I highly recommend the book "Mutants" by Armand Marie Leroi...its in paperback for about $12 from Amazon...sounds sensationalistic, but its a very straightforward, highly readable (yet still a little technical) account of the types of genetic mutations that affect people, and how their inherited....Take care, Eric
 

aquacorps

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Ohio-Guy. Your post was very good. Factor V Leiden is responsible for most of my orchid purchases. Rusty
 
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