Author Topic: How can I tell if my key lime is a mutant or polyploidic?  (Read 795 times)

Melenduwir

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How can I tell if my key lime is a mutant or polyploidic?
« on: March 29, 2022, 04:39:09 PM »
I thought it would be interesting to try making bonsai - or at least dwarfed potted trees - at home, so I gathered seeds from local trees and from purchased fruit, and set about trying to sprout them.  I'd never had much luck growing citrus of any kind, but I had visited a different grocery and purchased some organic key limes and miniature pink lemons, and to my surprise and excitement I had a very good response, to the point that I had to give away some of the seedlings.

I kept four key lime seedlings, and after a year (warm season outside, cold indoors in a sunny window) three are between 8" and 11" tall.  The fourth, though, grew so rapidly that I had to move it out of the fast food soft drink cup I'd started it in and into a multigallon pot.  It's now roughly two and a half feet fall, and unlike the others hasn't branched.  Lately I've noticed signs that a new branch is budding near the top.

I did a little research and learned a lot about citrus genetics (special thanks to citruspages.free.fr, your site is great!) and was disappointed and intrigued to learn about polyembryony and nucellar citrus.  So all my key limes are clones of the original plant, and probably can't be crossed with most other citrus types available to me, oh well.  But that fourth...

I know for a fact it came from the same key limes as the others, and its leaves are similar enough that I'm sure it's the same species.  But its behavior... they all ought to be more or less identical, right?  How can I tell if I have a mutant or polyploidic version of the key lime?  And if this plant really is genetically different, what are the chances that it might be worth keeping?  (Not in a monetary sense, but as an interested gardener.)

pagnr

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #1 on: March 29, 2022, 05:31:31 PM »
Key lime produces highly uniform seedlings. If you examine a group of seedlings, you will see they all have the same leaf size and shape, leaf margins, thorn size, foliage colour etc etc. None will jump out re seedling vigour, although there may be slight differences due to seed size. If you visually examine your seedlings, as you have, and one stands out in the above characters, including vigour, it must be genetically different. It could be derived from mutation or cross pollination.
Visual examination is the most used method of grading Citrus seedlings, and is commonly used to discard off type Citrus rootstock seedlings highly clonal seedling lots.

Walt

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #2 on: March 29, 2022, 11:37:53 PM »
Sounds like a cross.  Crosses are extremely rare in Key limes, but not impossible.
Mutants are also possible in any variety.  But without radiation or certain chemicals, they are rare too.
Don't throw it out. 
If it doesn't branch. use a single edge razor blade to make a cut into the cambium just above a bud.  The bud should start growing a branch.

pagnr

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #3 on: March 30, 2022, 07:12:03 AM »
Mutants are also possible in any variety.  But without radiation or certain chemicals, they are rare too.
Citrus can produce offspring with different chromosome numbers, i.e. ploidy, resulting from the movement of chromosomes at cell division. These plants can quite different to the normal chromosomal numbered plants.
True mutations are probably quite rare, although sunlight and Ag chemicals could be factors.
« Last Edit: March 30, 2022, 07:15:35 AM by pagnr »

hardyvermont

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #4 on: March 30, 2022, 12:48:17 PM »
Polyploid plants often have thicker leaves and more serrated leaf margins

pagnr

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #5 on: March 30, 2022, 03:46:50 PM »
A photo of your off type key lime would be welcome. Interested to see it.

Melenduwir

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #6 on: March 31, 2022, 05:45:57 PM »
I'll work on that.  Gotta find the charging cable for my flip phone so that I can upload photos to my laptop.

I measured them again this morning.  The 'normal' seedlings have gained a little height over the last six months, but they've been on a windowsil while the potted seedling has necessarily had less light and heat.  It's still twice their size.

Millet

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #7 on: April 01, 2022, 11:47:00 AM »
melenduwir, the growth pattern of the sun light and the non sun light seedlings is common.  The seedlings in the non-sunlight area are reaching for light, thus taller than the sun seedings.

Melenduwir

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #8 on: April 01, 2022, 03:44:23 PM »
But the tall one got that way when I had them all outside in the same place.  It hasn't done much of anything since I brought it indoors, which doesn't surprise me - it's alive and healthy enough, but it hasn't had enough heat and light to do much growing.

The three right next to a windowsill and above a heating vent have put on a little height, but they're distinctly smaller.

Egggh, I've gotta find that cable...

Melenduwir

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #9 on: April 08, 2022, 10:25:10 AM »
A photo of your off type key lime would be welcome. Interested to see it.

Finally got the phone working this morning!

Here's all four of them lined up:


The first, which is smaller than the others, bushier, has branched multiple times, and has smaller, softer thorns: 


The second plant has gained roughy two inches over the winter.  It's like the third, only a bit larger: 


The fourth had to be repotted because it kept falling over in the breeze.
 

A closer view of #4's half-inch-long thorns.
 

[edit]  That method of adding images didn't work... let's try this one.
« Last Edit: April 08, 2022, 10:31:17 AM by Melenduwir »

pagnr

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #10 on: April 17, 2022, 07:30:55 PM »
Thanks for the photos. Overall they look like seedling West Indian Limes to me.
#1 looks interesting, seems to have thicker leaves, but hard to tell from the image ?
#4 seems more vigorous.
I grew a few hundred W I Limes last year, hoping for some variation, you seem to have done better than me.
I don't think my seedlings are very thorny. The presence of thorns may just be a reversion in that trait, or maybe linked to the vigour.
As I recall thorny Citrus in the tropics can be a problem, where any spiked fruit on own thorns quickly get fungus and go off in humid weather.
Perhaps lack of thorns has been selected for in W I Limes, and yours threw back.
Although they are clonal from seed, There are quite a few selections of W I Limes in horticulture, and where I found them in the Queensland rainforest, a fair range of fruit sizes on different trees.
Generally they are fairly fast to fruit from seed, looking forward to further updates.

Melenduwir

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #11 on: April 17, 2022, 07:54:11 PM »
Thanks for the response.  I might have gotten lucky and had some zygotic seeds, although I can't find any statistics on how often Key limes are nucellar.

Kevin Jones

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #12 on: April 24, 2022, 07:28:28 PM »
For wha it's worth... I've had several Key Lime/Finger Lime crosses that have matured and fruited.
Bumble Bees did the crosses for me.

Kevin


BohicaBob

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #13 on: April 24, 2022, 08:00:57 PM »
How about Key Limes that were grown, generation after generation based on their size?  One fruit club member planted the seed of the largest key lime fruit he found in 1951. Then when this tree produced fruit, he planted the seed of the largest fruit on that tree.  On and on.  I got the 10th generation Key Lime tree from our fruit club's raffle table.  Most of the fruit on this tree are 2"x1".  But in 2019, one fruit on my tree was 3"x2" but it had only one seed which I planted and keep it a pot, waiting for fruiting.


pagnr

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #14 on: April 25, 2022, 05:09:30 AM »
"How about Key Limes that were grown, generation after generation based on their size?"
Genetic Science would probably say no difference, in selecting seed from individual large fruit from plants, rather than going further and selecting offspring plants with larger fruit in further generations.
That said, you could also consider that larger fruit may often have larger seed with larger embryos, and these may be genetically larger fruiting plants ?
So there may possibly some transmission of fruit size increase by this method.
You could also select larger seed from out of any of the fruit for the same result, if seed/embryo size does transmit vigour.
It is known that seed size in Citrus does relate to the genetics of the embryo inside, and small seed are often screened from rootstock seedlots to get rid of off types.

pagnr

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #15 on: April 25, 2022, 08:08:48 PM »
For wha it's worth... I've had several Key Lime/Finger Lime crosses that have matured and fruited.

Very interested to see some photos if possible, A friend is also trying those crosses.

Melenduwir

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Re: How can I tell if my key lime is a mutant or polyploidic?
« Reply #16 on: April 26, 2022, 03:52:25 PM »
Were the Key Limes the pollen or seed parent?  Several important citrus varieties are known to have been derived from Key Lime pollen, but its seeds seem to be highly nucellar.

 

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