I joked that as Citrus get more hardy, they develop more leaves. This gene map seems to point to the opposite. Trifoliate being the elder species and as citrus become more tropical, they lose leaves.
You might like this old article AN ANTIFREEZE FOR CITRUS TREES? ā Orlando Sentinel
"
AN ANTIFREEZE FOR CITRUS TREES?
By Tom Moore Of The Sentinel Staff
Orlando Sentinel
May 30, 1992 at 12:00 am
Now that the Food and Drug Administration has approved a genetically engineered tomato, can antifreeze for citrus trees be in the future?
At the U.S. Department of Agricultureās Agricultural Research Laboratory in Orlando, geneticist Randy Niedz is experimenting with a gene derived from arctic fish that, if inserted into citrus cells, might make citrus plants more resistant to cold weather. The gene, in effect, would be an antifreeze for oranges and grapefruit.
He stressed that although scientists now can clone a citrus plant from a single cell and that recent research has shown that foreign DNA can be inserted into citrus cells, there is a lot of work to be done before developing an antifreeze. The genes would be put into a citrus cell, and a tree would be grown from that cell.
Scientists then would have to determine if the geneās properties are transferred to the plants. The next step would be field tests to check for cold hardiness and to see if the plants grow normally. That testing, to see if the gene works, can be done in about a year.
After that, it would be at least four years before the citrus trees bear fruit. About three years after that, researchers would test the fruit for juice, flavor, nutritional value and other traits. So developing the citrus antifreeze would take from seven to 10 years."
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Thatās true. I get very happy when itās snow and not a clear night dropping into the teens. So far the yuzu have survived to 18 with just leaf drop. A tree in Portland reportedly survives 16 with just leaf drop. From what Iāve seen surviving to 15 is a reasonable expectation for a mature Yuzu. I have killed young Yuzu in zone 9 by exposing them to temps in the high 20ās. They really need to be grown in a greenhouse or brought inside for the first 2 winters minimum. Personally Iād go 3 or 4 winters before planting them outside in a zone 8 or a cold zone 9a. Even in Santa Rosa, Ca where you can literally grow almost anything I managed to kill a meyer lemon and an avocado the first winter because I was distracted and didnāt protect them at 30.
Thatās consistent with some stuff Iāve read. Itās definitely coming thatās for sure. Weird Frankenstein trees. It still weirds me out when I go to buy my pet fish and some tanks have them glowing like a highlighter marker.
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One of the hardiest satsuma/trifolate hybrids is known for having very sparse foliage.
Snow doesnāt rot it. Water might rot it when the snow melts if you have very poor drainage. But the amount of water produced by snow is small and drains into the soil very slowly. Ten inches of snow produces about one inch of water.
Iām looking for poncirus āsnow dragonā
Any chance youāre grafting that?
Scott
They send fragile sticks, that can not handle normal grafting, they are only intended to be used for bud grafting, they crushed when I tried using non bud grafting. That happened when I ordered from both California and from Texas. Yet From Texas the budwood can be requested harder, I am thinking that maybe the CCPP could too. Yet they never answered my e-mail asking them
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These people appear to be the people who made it Poncirus trifoliata 'Snow Dragon' ā Nurseries Caroliniana
A chimera is basically useless for breeding, pollen and seed would be from one or the other fused layers of tissue, not both/intermingled.
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Thank you.
I had one, but it was damaged by a contractor for the cable company (and I didnāt notice it right away)
Where I had gotten mine
Its been sold out everywhere for a couple yearsā¦
Scott
Have you tried contacting them, maybe they could at least tell you something, like when they may be selling it again, who knows maybe they could sell you a cutting.
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Good to know! I am mostly planning to graft them on small potted seedlings that also have very fragile stems, so itāll be a nice double challenge.
My root stock is very hard, I had 100% failure, since I had/have no experience with bud grafting I got very anxious, and I am not good with a knife so I did not think that I could do a successful bud graft, after I gave up regular grafting, I tried to root the remainder, and that was a total failure
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Iāve had very good luck with CCCP budwood. They also last well in the fridge. Iāve both successfully grafted and budded them.
They often send a lot more buds than you paid for.
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So youād get either the part from the trifolate or the satsuma? Thatās makes sense actually. I remember a story about a woman accused of welfare fraud because her children tested as her nephews. Turned out she was a chimera and the sibling part of her dna made the children she had. They even put her in jail until her lawyers finally figured out she was a chimera and got a specialist to testify. This was the state of Michigan and itās a fascinating case. I hadnāt thought about that case until I read your comment. Then it clicked. So cloning is the only way to get an offspring with all the same characteristics.
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Grafting citrus is not difficult but many details have to be correct or it will not work. BuddingNotes - mrtexascitrus
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Exactly. 
I remember that womanās legal wrangling. A chimera is a breeding dead-end, but they, as themselves, can be quite useful.
I have a number of Citrus Hybrids that were recovered as seedling survivors after a low of -12Ā° F. 3 have flowered and one has fruited. The fruits are acidic, but make an excellent beverage when diluted at a 30% juice/70% water ratio. The drink does need to be sweetened. The flesh and juice are both orange in color. The tree is in good condition following 2Ā°F and high winds.
Another selection has been tested for ploidy and has been determined to be Tetraploid. It has neither flowered, nor fruited at this point. There are additional survivors that havenāt flowered to this point.
This group of trees had the first flowers at 3 and 4 years of age. The first fruits were on the same age trees.
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My knowledge of plant genetics is rudimentary. However, I remember from the documentary that in a human chimera they carry two sets of DNA, one that is from the personās mother and father, and one that is absorbed from a sibling made from the same mother and father. So the human chimera has their own ānormalā DNA as well as their absorbed siblingās DNA. And during reproduction some of the chimera womanās eggs will have her own expected DNA as well as the absorbed siblingās DNA. So the offspring of a female human chimera can have children that possess DNA from her and a father, or DNA from the absorbed sibling and a father. So when you test her children they can have the DNA of a typical offspring or DNA that marks them genetically as a niece or nephew.So it isnāt a dead end in humans. I have no idea how chinerism plays out in plants. Hereās a basic overview of chimeric reproduction in humans:
https://www.thetech.org/ask-a-geneticist/chimeras-are-not-more-likely-have-chimeric-children