These fruits are not seedless, as was expected, but produce some nucellar bud embryos, as do many citranges after the development of the ovules has been stimulated by pollination. Triploid limes are usually seedless.

Bob,

I would expect an embryo rescue could be done if someone wanted to see if a plantlet could be grown in a lab. Seedless grape breeding is done this way at SunWorld as I witnessed when I worked for them.

I expect that serious variety introductions will occur from embyro rescue tissue growth attempts in many seemingly seedless creations.

Tom

Tom,

Thank you for your comments. I've much to learn about embryo rescue but I'm sure you are correct about serious varieties being introduced from embyro rescue tissue growth attempts in seemingly seedless creations. I'm reading that it is not an easy procedure for the home enthusiast because of the sterility issues.

Bob

Citrus classification and nomenclature was and still is a mess, but has been cleared up a bit since 1948.

This is not a true trigeneric hybrid, since only 2 genera (Fortunella and Citrus) are involved--and even then it is only marginally bigeneric. Recent studies indicate that Fortunella should probably be included in the genus Citrus. The two are certainly closely related.

Poncirus (hardy or trifoliate orange) is a very closely related genus and will also cross with this group; I suppose a lumping taxonomist might place it too within Citrus. The fruits are certainly citrus-like. This genus is interesting because it imparts greater cold-hardiness to hybrids.

However, there are many examples of trigeneric hybrids (and more!) in Orchidaceae. Since there is no objective definition of "genus" and generic circumscriptions are artificial, I'm not sure how much this means anyway. I suspect it means the orchid genera are over-split.

Hum... could this be a trigeneric hybrid:

(Tripsacum doctyloides x Zea diploperrenis) x maize

A few newer articles that I've read on the net said that one fertile hybrid has been secured. I forgot what link it was, but I'll search for it. I'm so intrested in this that I have obtained seeds of tripsacum and diploperrenis in my own attempts of creating my own hybrid. Tripsacum is coming from Sweetbriar Nursery in Texas, and diploperrenis is coming from an nice Austrailian woman.

Enrique

Good News regardless, Bob and Tom; you won't have to mess with embryo culturing in this case.
"Nucellar bud embryos" means just that the embryos were produced entirely from the mother plant and don't include genetic material from the pollen. They produce normally viable seed in Citrus.
In fact, when you plant seeds of many common Citrus fruits from the grocery, you'll notice often 2 or 3 seedlings from one pit- the largest and most vigorous are usually the nucellar ones.

V

hi does anyone know of any embryo rescue information on the net or can anyone send me some please as i cant wait to create something new using this method thanks kevin.

can anyone put some info on embryo rescue on this forum please.

Hurray, I've gotten both Zea diploperennis, and Tripsacum Doctyloides. I have planted a few Tripsacum seeds, as winter is coming soon, and think they will stratify like that. The others are in bags of moist soiless mix. I will not plant ZD until next coming spring. I enjoy collecting seeds, and throwing them at odd places lately. This year, purple morning glory vines wrapped around climbing rose Sombrieul. What a perfect combo! Purple againts pure white roses. It helped slightly to cover its bare leggy canes. I have a tone of beans by throwing them. They climbed up a television cable, and I have so much beans from one plant. This year, I have thrown some open pollinated black hollyhock seeds, passion flower, etc,.. Doubt all of them will grow to survive. Lets see what will survive by itself.

Enrique

We may note that embryo rescue isn't the only possibility with difficult seeds. Endosperm can be cultivated on a callus inducing medium, then encouraged to develop adventitious shoots.

Some hybrids fail to develop roots, but this technique has proven successful in some cases. It might even be used with hybrids that degenerate before the seeds have ripened (like some tomato hybrids). Endosperm is a hybrid tissue, but is formed from different cells than the embryo.

http://www.i-a-s.de/IAS/botanik/kranz/St-Louis.htm
http://www.agron.missouri.edu/mnl/66/123faranda.html

Here is a link that might be useful: Recovery of callus lines

Also important to note is that the endosperm is 3n. This leads you down another merry path of problems.

Plant Geek,

But if the pollen parent is a tetraploid and the seed parent a diploid, then the endosperm could be tetraploid -- two sets from the seed parent.

Yet another path for amusement.

Karl King

From folks I've talked to who've been there, Sun World is indeed doing a serious amount of embryo rescue. It's a labor intensive, relatively low yield task, but if you're breeding for seedless table grapes, one must compare that effort to the amount of time and resources that would go into growing out hundreds or thousands of seedlings which would ultimately be rejected once they proved to be seeded.

To my knowledge, Sun World is the only grape breeding program attempting this on any scale. There were one or two embryo rescue seedlings kicking around when I was at Cornell, but we never did any while I was there.

Hmm, I wonder why it wouldn't be cost effective to hybridize seedless grapes and raise the seedlings --
I read over 15 years ago that some seedless grapes produced
seeds that are viable. Something like "Thompson Seedless" where the seeds are almost invisible specks would not be, but "Canadice" a popular home variety of 'seedless' grape, actually has quite large seeds, they just never harden. And there is a range of seedlessness between these extremes. I would think that crossing something like "Thompson Seedless" as a pollen parent with something like "Canadice" as seed parent would produced a high rate of viable seedling with most of the plants being seedless(and cheaper than embryo rescue). I would also think that a rescued embryo would not be guarenteed to be seedless.

Two reasons I can think of why this would be more effective for them: The genes that make "Thompson" and "Canadice" 'seedless' may be different mechanisms, so that in crossing them, the resultant seedlings might actually be seeded.

2nd reason: For SunWorld, maybe only the miniscule/nonexistant pips like in "Thompson" are acceptable commercially, so that they concentrating on only the most seedless types.

About grape breeding: you gotta answer the question of whether the seedless characteristic is either dominant or recessive!