Seedless Cherimoya article- 2011

[Adacaosky]

Seedless Cherimoya, the Next Banana?
ScienceDaily (Mar. 15, 2011) — Mark Twain called it "the most delicious fruit known to man." But the cherimoya, or custard apple, and its close relations the sugar apple and soursop, also have lots of big, awkward seeds. Now new research by plant scientists in the United States and Spain could show how to make this and other fruits seedless.
Going seedless could be a big step for the fruit, said Charles Gasser, professor of plant biology at UC Davis.
"This could be the next banana -- it would make it a lot more popular," Gasser said. Bananas in their natural state have up to a hundred seeds; all commercial varieties, of course, are seedless. A paper describing the work is published March 14 in the journal Proceedings of the National Academy of Sciences.
Researchers José Hormaza, Maria Herrero and graduate student Jorge Lora at the Consejo Superior de Investigaciones Cientificas in Malaga and Zaragoza, Spain, studied the seedless variety of sugar apple. When they looked closely at the fruit, they noticed that the ovules, which would normally form seeds, lacked an outer coat.
They looked similar to the ovules of a mutant of the lab plant Arabidopsis discovered by Gasser's lab at UC Davis in the late 1990s. In Arabidopsis, the defective plants do not make seeds or fruit. But the mutant sugar apple produces full-sized fruit with white, soft flesh without the large, hard seeds.
The Spanish team contacted Gasser, and Lora came from Malaga to work on the project in Gasser's lab. He discovered that the same gene was responsible for uncoated ovules in both the Arabidopsis and sugar apple mutants.
"This is the first characterization of a gene for seedlessness in any crop plant," Gasser said.
Seedless varieties of commercial fruit crops are usually achieved by selective breeding and then propagated vegetatively, for example through cuttings.
Discovery of this new gene could open the way to produce seedless varieties in sugar apple, cherimoya and perhaps other fruit crops.
The discovery also sheds light on the evolution of flowering plants, Gasser said. Cherimoya and sugar apple belong to the magnolid family of plants, which branched off from the other flowering plants quite early in their evolution.
"It's a link all the way back to the beginning of the angiosperms," Gasser said.
The work was funded by grants from the Spanish government, the European Union and the U.S. National Science Foundation.

http://www.sciencedaily.com/releases/2011/03/110314152912.htm

[Mike T]

Cherimoyas may be catching up to atemoyas.This 5lb or so mammoth had only a couple of non viable slips.Top atemoyas have a proportion of seedless fruit already and mammoth lines with few seeds have been around for 100 years.

Just what fruit Mark Twain was referring to from Hawaii and if he tasted it himself has been open to speculation.

[FlyingFoxFruits]

wow! impressive!

I love the pic...it reminds me of a bread fruit some how

Once again, your glass table has seen more amazing fruits than most people I know.

[JF]

Cherimoyas may be catching up to atemoyas.This 5lb or so mammoth had only a couple of non viable slips.Top atemoyas have a proportion of seedless fruit already and mammoth lines with few seeds have been around for 100 years.

Just what fruit Mark Twain was referring to from Hawaii and if he tasted it himself has been open to speculation.

Dario from cherimoya.com had a table full of 4-5pound Pierce last year at the Cherimoya taste testing event . Check out the pics in that thread,

[fyliu]

Dr. Gasser was the featured speaker at last year's annual cherimoya association meeting. He came up with several ways to get to the end goal of seedlessness and a number of members offered to grow out the experimental trees if he's able to produce them.

[Californiatropicals]

Dr. Gasser was the featured speaker at last year's annual cherimoya association meeting. He came up with several ways to get to the end goal of seedlessness and a number of members offered to grow out the experimental trees if he's able to produce them.

That would be amazing,... even a low seed cherimoya would be great... definitely something that would be worth growing IF they could do it without compromising the amazing flavor.

In general I don't mind the seed count of named varieties.. they slow the eating process and allow me to savor the flavor more.. however, I've had seedling grown cherimoyas (from a local asian market) and they had a ridiculous amount of seeds.. I'd say at least 50 in a small/ medium fruit.. less than a pound.. That was not enjoyable!

[fyliu]

I've had seedling grown cherimoyas (from a local asian market) and they had a ridiculous amount of seeds.. I'd say at least 50 in a small/ medium fruit.. less than a pound.. That was not enjoyable!

Yeah, I had the same experience with sugar apple in China last October. Nice and ripe but 50+ seeds in an average-sized sugar apple is too much. The seeds were thicker than the spacing between them.

[Guanabanus]

Sounds very interesting.

I hope that seedless cherimoyas are not lower in flavor than seedy ones, as is the case with sugar-apples.

[fyliu]

Wait, the Thai seedless sugar apple has less flavor than the average? I was told it was the same size as regular ones but nobody mentioned flavor. Maybe that's why. Or we're you talking about some other less seedy sugar apple?

[Josh-Los-Angeles]

Does anyone have an update on the seedless Cherimoya project? Last news I could find of it online was back in 2011.

[fyliu]

Dr. Gasser is still developing it the molecular way (same species GM). I think he is (or is assisting in) simultaneously going the conventional route. DNA(PCR) can be used to figure out if the seed development gene is absent in a seedling before it ever fruits.

The Spanish are one or a couple generations ahead with the conventional breeding.

[Josh-Los-Angeles]

Thanks for the info. I'm completely on board with GMO for this exact reason -- I can't possibly see what the downside is of speeding up the incredibly lengthy process of hybridization and trait selection. Seedless cherimoya, seedless mango, seedless everything.

[Bush2Beach]

Square watermelons, fruit that never spoils and tree ripens year round....er naah not for me.
Apparently Chuck the molecular biologist that works at UC davis separated the INO gene. The same mutant he worked on with the Spanish. The Spanish took this information and are a generation ahead of creating the seedless cherimoya , which is well in its way. So the Spanish will get there first and they have the commercial orchards and infrastructure to go big when it happens.

[ben mango]

Lol could be the next banana except they won't fruit year round and this not much of a food staple

[fyliu]

With traditional breeding, they get seedless atemoya (cherimoya x sugar apple). Then cross it back with cherimoya several times to get it to as close to cherimoya as possible. They want cherimoya, not atemoya. So start with 50%, then 75, 88, 96, 98, 99. That's 5-6 generations. But maybe they can do some selection during that process to get a good tasting fruit out of it.

With Gasser's method, it's 100% cherimoya from the first generation. The trick is messing up that gene without affecting anything else. Ideally just add a single DNA pair in the middle of it so the protein is no longer the correct shape. Not sure how easy that is.
It would still take some breeding and selection to get good quality.