Citrus Growers Forum

GoneBananas · Citruholic Joined: 12 Jan 2006 Posts: 45

I understand the basic genetics, I think. Most embryos are from "mother tissue" and will be clones of the parent tree. But some are not.

Are most seeds totally clonal, with all embryos from the seed parent?
or
Do most seeds have both?

If the second:

Are the sexual embryos outnumbered?
Are they usually out-competed in growth?

Can you tell which sprout is what?

Say in 100 polyembryonic seeds planted, roughly how many plants would be clonal? In reverse, what is your risk of not getting the variety you desired?

Thanks (Some mangoes are polyembryonic and form seed varieties too I recall. It was easy to see the multiple embryos in the husked seed.)

GoneBananas · Citruholic Joined: 12 Jan 2006 Posts: 45

I meant to put a "please" at the end of the title.
Sorry

Jtoi · Citruholic Joined: 29 Dec 2005 Posts: 52 Location: Canada

I think that this may clear up your questions of Polyembryonics (right word I hope):

http://lib.ucr.edu/agnic/webber/Vol2/Chapter2_4.htm#polyembryony

From the Citrus Industry Vol. 2,
Hope this helps,
Sincerely,
James.

JoeReal · Posted: Wed 22 Feb, 2006 2:22 pm

GoneBananas wrote:

I understand the basic genetics, I think. Most embryos are from "mother tissue" and will be clones of the parent tree. But some are not.

Are most seeds totally clonal, with all embryos from the seed parent?
or
Do most seeds have both?

Depends on variety and also if cross or self pollination has occured. Some varieties will not form seeds unless cross pollinated. In some cultivars, the nucellar embryos always outnumber the fertilized embryos on at least a 4:1 ratio while in others, the reverse is true.

GoneBananas wrote:

If the second:

Are the sexual embryos outnumbered?
Are they usually out-competed in growth?

Can you tell which sprout is what?

Say in 100 polyembryonic seeds planted, roughly how many plants would be clonal? In reverse, what is your risk of not getting the variety you desired?

Thanks (Some mangoes are polyembryonic and form seed varieties too I recall. It was easy to see the multiple embryos in the husked seed.)

Again it depends on the cultivar and if cross pollination has occured.
If you have 100 seeds and you planted them, it is quite easy to know which are hybrids and which are nucellar. The ones that are more uniform in sizes and vigor are MOST LIKELY the nucellar or clonal type, the others are MOST LIKELY recombined or hybrids (zygotic). There is a chance that you will misidentify some of them, unless you use gas chromatography analysis or DNA analysis. The outliers are easily identified and usually helps the breeders spot easily the hybrids which they are after.

If you open up a just sprouted Calamondin seed, you can see the multiple embryos when you peel off the seed cover.

GoneBananas · Citruholic Joined: 12 Jan 2006 Posts: 45

Thanks for the link and the explanations. I have interest in two ways. I want to know how certain (or uncertain) I am in having a "variety" from seed, and secondly in sorting out the uncrossed in a future experiment or two.

Malcolm_Manners · Posted: Sun 12 Mar, 2006 9:03 pm

There would never be more than one sexually produced embryo in a seed. And in most citrus, even that one dies out in most cases. So for most varieties, most seeds have nothing but nucellar embryos left. And at worst, you get one hybrid embryo. Most varieties won't produce any nucellars until a sexual (zygotic) embryo gets started, since it is the gibberellin given off by that embryo that stimulates the nucellus to make more embryoids. But then the nucellars tend to outgrow the zygotic embryo, and it ends up dying.