Tobiano - strange happenings...

[Nazarach]

Now that would make absolute sense, so just like Lp, it's a two-gene control, a switch for on/off and then also the actual patterning genes carried separately.

(I've also found no Lp carries without some sort of visible indicators)

I thought we had a couple players that were going to work a little on identifying some of these To genes? I was waiting to see a topic about it, but... did I miss it? All I've seen are 'favorites' patterning posts.

I read the same, but haven't seen anything come of it. The most I've seen is people focusing on facial white, but even then it just looks like people breeding them for fun/to sell them off rather than figuring the genes out. Perhaps we should make one like the leopard topic.

the two-gene control sounds like it could work for these strange cases, but more facts/research in Tobiano would be really nice... Regarding breeding for certain expressions or getting them out of a line it just seems often like to much of a hit and miss for it to be 'simply' dominant :/
And many thanks for your input, I wasn't sure if there were other cases so your feedback helps a lot

[Argent]

All current white markings are minimal expressions of tobiano. RL white markings have been linked to the KIT gene (tobiano, sabino, etc.) or somewhere close to it. Horses can carry genes but not express them; once crossed with another carrier, you get foals with white markings.

[Aela]

All current white markings are minimal expressions of tobiano. RL white markings have been linked to the KIT gene (tobiano, sabino, etc.) or somewhere close to it. Horses can carry genes but not express them; once crossed with another carrier, you get foals with white markings.

Do you know of any studies that have linked white markings to KIT (or close)?

Last thing I heard was that it was speculated the foal's placement and the environment in the womb had some sort of effect (along with an unknown genetic component)

[Aela]

Nevermind, I actually found a study linking white markings close to KIT an MITF + a couple of debates on the topic :)

[Silverine]

So, I thought Tobiano was dominant?
My mare just threw a foal that has a little sock when neither her nor the sire had a To expression...how come?



Sire http://www.horseworldonline.net/horse/profile/1619760
Dam http://www.horseworldonline.net/horse/profile/1378097

So I bred your boy to an AC NAB that I picked up that had no visible To, and they threw a baby with some little socks.




This is mom:



I also bred Roberto to one of my painted mares and they threw a baby with tiny socks as well, rather than the loud markings of the dam (unfortunately I didn't keep the baby, so no pics - this is the mare I bred him to). My current working theory is that Roberto carries To but no white factor. Of course the opposite could be true - the unmarked mares could be the carriers without the white factor - but it makes more sense to me that Roberto would be white factor deficient since he threw the small sock baby with my loud mare.

[redster]

I don't know if it helps, hurts, or doesn't matter at all to the two-gene theory, but I thought it might be interesting. This little filly comes from a mare who has a couple tiny socks in her short lineage, and her sire is an AC guy who was adopted before Tobiano was released. All horses involved were Tarpans.

Tonic

[Argent]

There is, effectively, a gene for every single marking. So not two genes, but very many.

[AltNazarach]

So I bred your boy to an AC NAB that I picked up that had no visible To, and they threw a baby with some little socks.




This is mom:



I also bred Roberto to one of my painted mares and they threw a baby with tiny socks as well, rather than the loud markings of the dam (unfortunately I didn't keep the baby, so no pics - this is the mare I bred him to). My current working theory is that Roberto carries To but no white factor. Of course the opposite could be true - the unmarked mares could be the carriers without the white factor - but it makes more sense to me that Roberto would be white factor deficient since he threw the small sock baby with my loud mare.

Thanks for an effort with your time it's helpfull to know that it was (very likely) the sire.

[AltNazarach]

There is, effectively, a gene for every single marking. So not two genes, but very many.

You mean like a To-variant for the legs, one for the paint-markings and one for the face-markings? But how does this factor in the current case? two seemingly non-carriers having a foal with an expression when To should be dominant? :/

[BlackOak2]

There is, effectively, a gene for every single marking. So not two genes, but very many.

You mean like a To-variant for the legs, one for the paint-markings and one for the face-markings? But how does this factor in the current case? two seemingly non-carriers having a foal with an expression when To should be dominant? :/

The two-gene I was referring to is the 'switch' gene. To turn the expression of the To on or off.
And the pattern gene, which really is the combination of all the rest of the patterning genes for To. This is why there is 'very many' and 'for every single marking' (at least that's what I assumed Argent refers to). This is the same way that Lp was introduced. And quite possibly works very similarly to Lp as well, such as 'when you fill your cup for certain areas, your cup overflows and begins filling other areas'. For Lp, this is how we went from hip blankets to full-coverage leopards.

But that was my suspicion and that is my theory. I don't know if I'm correct or not, but using this theory, it makes sense when applied to these horses.

When one carries To, but no switch = no markings.
When one carries switch, but on To = no markings.
When passed on to the foal, switch & To = markings.
Therefore, two totally unmarked horses, can produce a marked offspring.

That being said,

http://www.horseworldonline.net/horse/profile/1635152

doesn't necessarily fit into the 'cup overfloweth' theory.
This foal from Redstar is the reason why it would be nice to have some research done on the To. So perhaps a bit more understanding can go into what Tobiano genes are likely to produce.