Amoa 8 Blood Mandarin…woah!

[Tortuga]

Anybody eaten or grown this cold hardy citrus? Just got mine in the mail. I see that it’s pretty seedy. Bummer. Cold hardy to 15 on flying dragon rootstock

https://citrusvariety.ucr.edu/crc4237

[Till]

I have it. It is really dark red every year and tastes sweet. A bit small the fruits and not the complex special aroma of Moro blood orange but definitely tasty. Blooms willingly.

But I do not believe in the hardiness claims. Such a hardiness is totally unlikely given the parents of Amoa 8. I would assume that it is not hardy at all, not more than any common citrus. I have seen that Italian nurseries often make totally exaggerated claims of hardiness. I do not know how they come to these data. They even state that pure Pumelo is hardy to -10°C (14°F) or sour orange hardy down to -15°C (5°F) which is foolish. I shall believe that they survive such temperatures for one hour without any wind when temperature is then again above freezing. But that is not the hardiness we use to speak about here. If Italian hardiness claims were true noebody would waste a thought about (really) hardy citrus.

[vnomonee]

is anyone trying to cross these with trifoliate? blood citrandarins

[Till]

Yes, myself. I am not sure if there are hybrids among the seedlings from last year.
Amoa8 is largely nucellar. But I had seeds with pale color besides the normal green seeds in one year. Unfortunatelly, I lost all seeds in that year.
I still wonder why we have no colorated citranges although Ruby Red was often used in breeding. I fear that Poncirus blocks pigmentation. We will see what happens with Amoa 8 crosses.

[mikkel]

just a thought I suspect Ruby Red / Pt hybrids backcrossed with Ruby Red should show some "Blood" genetics

[vnomonee]

just a thought I suspect Ruby Red / Pt hybrids backcrossed with Ruby Red should show some "Blood" genetics

This sounds about right. I don't know much about genetics but perhaps the pigmentation needs 2 copies of the gene? So maybe an amoa8xpt citrandarin crossed with another amoa8xpt citrandarin or one of the existing ruby pt hybrids = offspring w pigment?

[Till]

Concerning the genetics of the blood oranges, I have read the following:
1. All Sweet Oranges contain only one functional copy of the Ruby gene. It is though inactive in all of them except the blood oranges. The blood oranges possess a mutation that activates the Ruby gene under cold stress so that it produces the color of the fruits. Its original function seems to have been rather different, namely light protection in young shoots and leaves. 2. Poncirus possess two functional copies of the Ruby gene. Poncirus does, however, not produce red fruits because the Ruby gene is only active for light protection. 3. Mandarins do not posses a functional Ruby gene.

So all crosses of blood oranges with Poncirus contain at least one functional copy of the Ruby gene, the one from Poncirus. 1/4 of them should contain the mutation attached to the Ruby gene that causes red coloration of fruits. 1/4 posses the Ruby gene for light protection from Poncirus and a dysfunctional Ruby gene from the orange part.

So no F1 cross of Poncirus with Blood Oranges possesses more of the Ruby gene (with mutation) than Blood Oranges themselves. The difference is only that thoses F1 crosses having the Blood Orange gene also posses another functional copy of the Ruby gene in its original state, where Blood Oranges have a dysfunctional copy.

The big question is now why we do not have blood citranges. The answer can in my view be threefold: 1) By chance. When only 1/4 of all crosses have the genes for bloody fruits then we perhaps just had bad luck and got only the 3/4 without the desired genes. 2) The functional copy of the Ruby gene in its original state undermines the activity of the mutated Ruby gene. 3) Citranges just do not feel the cold stress that is needed for activation the Ruby gene from Blood Oranges.

So far my memories and conclusions. I am looking forward for your comments / critic, and sugestions.

[mikkel]

This suggests a backcross

[Ilya11]

Could be because  other regulator genes (bHLH) from poncirus required for anthocyane synthesis do not functionally match MYB factors from blood orange.

"It has been observed that there is
a requirement for the presence of a suitable bHLH partner to
achieve full functionality in the heterologous system"

link

[Till]

...what would be an annoying problem for breeding.

I try to make crosses between Moro and C. ichangenesis and Amoa8 and C. ichangensis. I hope that helps. One hybrid so far but I don't know if it has the gene for coloration.

[Lauta_hibrid]

https://citrusvariety.ucr.edu/crc301



about hybrids with Ruby orange and poncirus I remember this part of the text, but no one has Rusk citrange that I know of, does anyone have it to confirm?

[bussone]

https://citrusvariety.ucr.edu/crc301



about hybrids with Ruby orange and poncirus I remember this part of the text, but no one has Rusk citrange that I know of, does anyone have it to confirm?

Stan McKenzie and Oscar Tintori carry it. I'm not sure that helps you in Argentina, though.

[Till]

I have it since last year. It is just a small rooted cutting. I do not know importation rules of Argentinia. But you may ask me in summer when it is hopefully so big that I can cut off a twig for you.

[Lauta_hibrid]

With will, everything is possible hehe, but it is difficult to import.  Maybe my curiosity is theoretical, since I don't know if that red blush on the fruit is an expression of the Ruby gene.  You should see a fruit that has been cold, because Óscar Tintori has a greenhouse and I don't think it is that cold.  Has anyone already had or seen the fruit?  or tried it to buy with Morton?

[countryboy1981]

I have it. It is really dark red every year and tastes sweet. A bit small the fruits and not the complex special aroma of Moro blood orange but definitely tasty. Blooms willingly.

But I do not believe in the hardiness claims. Such a hardiness is totally unlikely given the parents of Amoa 8. I would assume that it is not hardy at all, not more than any common citrus. I have seen that Italian nurseries often make totally exaggerated claims of hardiness. I do not know how they come to these data. They even state that pure Pumelo is hardy to -10°C (14°F) or sour orange hardy down to -15°C (5°F) which is foolish. I shall believe that they survive such temperatures for one hour without any wind when temperature is then again above freezing. But that is not the hardiness we use to speak about here. If Italian hardiness claims were true noebody would waste a thought about (really) hardy citrus.

I have a few of these in the ground.  My place hit 16 degrees this winter on the 17th of January.  I banked soil around the young trees to protect them but it was not needed.  The branches above the banked soil survived with damage to the thinner parts.  It did warm up the next day well above freezing temperatures.  It was one of our colder lows for this area but not with prolonged temps barely above freezing for several days.

[Till]

A short time of freezing but nonetheless amazing how it survived.