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Old November 15, 2012   #1
tedln
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Default How to determine a sport!

How can you tell if you have a "sport" of an open pollinated variety versus an accidental cross of that variety and another variety?

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Old November 15, 2012   #2
bower
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I'll hazard a guess, and then find out what the real answer is.

I think by "sport" you mean a spontaneous mutation. That would be a plant with a single trait that is different from the parent plant. The "sport" would be identical to the parent in all other traits, including unchanged recessive traits (eg PL, yellow fruit, etc)

An accidental F1 cross would be an equal mixture of traits from both parents, and completely heterozygous, so a dominant trait from either parent would be expressed (eg RL, red etc).

I guess this is why the sometimes appearance of PL seedlings from RL 'mothers' is concluded to be a 'sport'. Any cross would be expected to express the mother's RL dominant trait, so the change of leaf type had to be a spontaneous mutation. The same goes for any single recessive trait, that appears in seedling from a 'mother' with the dominant trait - it could not occur in the F1 cross, so must be a mutation - unless the parents were not actually homozygous/stable varieties.
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Old November 15, 2012   #3
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that sounds good to me
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Old November 16, 2012   #4
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Thanks Bower,

I've read peoples comments stating they had a "sport" appear in their tomato plants with a number of different traits from the parent plant. Those have included fruit size, fruit color, and leaf type. It always seemed more like F1 crosses they were describing, but they never report if the offspring of the multi trait "sport" grows true the following year. I suppose Kellogg's breakfast and KBX would be an example of a true sport appearing.

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Old November 16, 2012   #5
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I'm not too familiar with the KB-KBX case, although I thought the 'X' referred to a cross. I'm also not sure about the 'sport' business and recessive traits like PL - it would require 2 mutations wouldn't it, for RR to change to pp, and I don't know enough about the mutation process to understand if this is likely or not.

I must admit, it's confusing when your plants are not true to type, and the mystery is more when you didn't grow the seed yourself! There may be too many unknowns to be certain of the reason.

For example, I had two of three Anna Russian seedlings which weren't true to type: all three were different. The third one was RL, not wispy leafed, and got stuck in the garden as an afterthought - the fruit were not heart shaped, but red and ruffled. I checked the other seed offerings by that company and found Costuloto Genovese as the most similar and likely parent of a cross. Except that, with all dominant traits making the F1 so similar to the parent, I really don't know if a wrong seed could have slipped into the package, either. I'll have to grow some out, to see if any of them are wispy leaved, or if not, I'll guess they are plain CG.
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Old November 16, 2012   #6
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If I remember the story correctly, a lady found a single PL KBX plant in her garden of KB plants. All other traits appeared to be equal except the PL plant has been reported to have more disease resistance and better taste. The KBX also reproduced true to type in its first generation from seed. That seems to fill the bill for a sport instead of a cross.

I grew Fred Limbaughs Potato Top this year and harvested a lot of seed. I germinated six seed in paper towels to check for viability (100% germination). One seed produced an RL plant while the other five were true to type PL. I didn't intend to grow them, but I was really interested in how they would compare in a growout. The RL plant grew at double the rate of the PL plants. While both have some small green tomatoes, I don't think they will produce viable seed before our first freeze. I will probably germinate 10 or 15 seed in the spring to see if I can get another RL plant from the seed and grow it out.

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Last edited by tedln; November 16, 2012 at 04:32 PM.
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Old November 16, 2012   #7
delltraveller
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I always thought a sport was something different on a normal plant, a branch or a single fruit that was different than the rest.
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Old November 16, 2012   #8
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tedln,

If the RL FLPT is a "sport" it would be one of a kind - not much chance of getting a second one if you can't get seed from this one. What a shame!

If the RL FLPT is a cross, you might get more of the same in your seeds. Or you may get crosses that are completely different, as I did (apparently) in the Anna Russian seed. The first one I had was a red heart with insipid taste and very corky center - not a keeper at all.

Either way, if you really don't want to lose this one, is there a chance of protecting it from frost? (C'mon, don't tell me you actually get hard frost in Texas! )
Or another thing you can do, is to take cuttings from the plant and root them in a glass of water. You can keep the 'clone' going on your windowledge if necessary, until it's safe to plant outside again. Hey, that's what we do in Newfoundland.

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Originally Posted by tedln View Post
If I remember the story correctly, a lady found a single PL KBX plant in her garden of KB plants. All other traits appeared to be equal except the PL plant has been reported to have more disease resistance and better taste. The KBX also reproduced true to type in its first generation from seed. That seems to fill the bill for a sport instead of a cross.

I grew Fred Limbaughs Potato Top this year and harvested a lot of seed. I germinated six seed in paper towels to check for viability (100% germination). One seed produced an RL plant while the other five were true to type PL. I didn't intend to grow them, but I was really interested in how they would compare in a growout. The RL plant grew at double the rate of the PL plants. While both have some small green tomatoes, I don't think they will produce viable seed before our first freeze. I will probably germinate 10 or 15 seed in the spring to see if I can get another RL plant from the seed and grow it out.

Ted
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Old November 16, 2012   #9
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I always thought a sport was something different on a normal plant, a branch or a single fruit that was different than the rest.
Good question and I have no idea. I guess I asked the question originally to get a clear answer in how to identify a "sport".

Bower,

Hey! I had four snowstorms winter before last and no snow last winter. That is the fun of winter in Texas, you never have any idea what winter will bring.

I've thought about taking some cuttings of the RL plant and growing them through the winter. I would need to grow them on the light table until I start germinating my spring garden seed in December. We don't have enough winter sunlight to do a good job of keeping a plant alive in a window sill. I may do it to see what happens.

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Old November 17, 2012   #10
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Quote:
Originally Posted by tedln View Post
I germinated six seed in paper towels to check for viability (100% germination). One seed produced an RL plant while the other five were true to type PL. I didn't intend to grow them, but I was really interested in how they would compare in a growout. The RL plant grew at double the rate of the PL plants.

Ted
That sounds like hybrid vigor, I would strongly suspect a crossed seed.
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Old November 17, 2012   #11
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Quote:
Originally Posted by delltraveller View Post
I always thought a sport was something different on a normal plant, a branch or a single fruit that was different than the rest.
It can be this, or it can also be the whole plant that is affected, if the mutation point occurs low down on the plant, or in the seed itself.
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Old November 17, 2012   #12
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"That sounds like hybrid vigor, I would strongly suspect a crossed seed."

Have you ever noticed how one answer leads to more questions? Hybrid Vigor? If two different varieties have genetically stable growth rates, how or why would crossing them create a hybrid with either a faster or slower growth rate? Is hybrid vigor a common trait of newly created hybrids? Will stabilization of a hybrid result in the loss of hybrid vigor?

"It can be this, or it can also be the whole plant that is affected, if the mutation point occurs low down on the plant, or in the seed itself."

Very interesting, but it still leaves the question of how to visually identify a "sport" versus a "hybrid" in your garden. I suppose if only one branch exhibits traits different from the remainder of the plant, it would be easy to identify as a sport. If the entire plant or seed of a plant produce a "sport", how is it identifiable as a sport?

Ted

Last edited by tedln; November 17, 2012 at 10:39 AM.
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Old November 17, 2012   #13
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The best way to tell is grow it out. Is the "sport" stable or does the growout produce only those 2 variations? Or does it produce a wide variety of different offsping like a hybrid would?

But I agree with maf. The fact that it showed BOTH increased growth AND a change in leaf type would suggest it is most likely an accidental cross. If the tomatoes are different or if you find yet another trait that differs it would pretty much be a certainty.

The odds of a spontaneous mutation is incredibly small. The odds that mutation would be beneficial is even smaller. The odds that mutation would cause 2 identifiable unrelated traits to vary is astronomically small. But if you find 3 or more traits affected you can say with a very very very high degree of confidence that it is an accidental cross or "rogue".

That's about the best anyone can say without doing an actual genetic test.

So the conclusion is you have an accidental cross or stray seed unless proven otherwise.
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Old November 17, 2012   #14
tedln
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Thanks Scott,

My interest doesn't lie so much in identifying my FLPT oddity. It lies more in being able to visually identify the difference between a sport and a F1 cross in any tomato plant.

I think the fact that multiple trait variants instead of a single variant would lend credibility to it's being a hybrid. I believe that is the point you were making. A single variant from the parent would have a higher, but not definitive probability of being a sport. Stable reproduction in successive generations will provide the highest probability of a sport.

Is that accurate?

Ted
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Old November 17, 2012   #15
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Quote:
Originally Posted by tedln View Post
Thanks Scott,

My interest doesn't lie so much in identifying my FLPT oddity. It lies more in being able to visually identify the difference between a sport and a F1 cross in any tomato plant.

I think the fact that multiple trait variants instead of a single variant would lend credibility to it's being a hybrid. I believe that is the point you were making. A single variant from the parent would have a higher, but not definitive probability of being a sport. Stable reproduction in successive generations will provide the highest probability of a sport.

Is that accurate?

Ted
Yes, in general terms, excluding extremely rare exceptions, that is accurate. It is theorectically possible for one gene change to have a cascading effect on other genes. So it is theorectically possible to get a sport with changes to more than one trait. But that is realistically not going to happen in yours or my lifetime unless we were specifically TRYING to make it happen. Even then it might not? That would require a genetics guy to explain. I work with real world stuff and as has been pointed out by some others at tomatoville in another thread, my knowlege of genetics is somewhat outdated and lacking to say the least.

I have however worked for a seed research company that developed seed corn (both sweet and field), soybeans, and tomatoes for commercial use. Whenever they saw a multiple variant "sport" it was automatically destroyed right away without even hesitation, unless it was in a very specific plot designated for that purpose. In fact, in most plots even one trait change got the plant destroyed. We called them "rogues" and they were ALWAYS destroyed no matter how pretty they looked. So real world practical experience I do have.
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