Breeding for improved beta-carotene

[crmauch]

I plan to breed for improved beta-carotene in a paste tomato. I know to some degree the presence of the desired genes can be discerned by the color of the tomato, but I believe to be truly accurate, the tomato would have to be tested. Does anyone have an idea where this testting could be done, and how much it would cost (I'm far from that point, but would like to prepare). Also is there any 'home-made' or home chemistry testing that could be used? (Even if not as accurate, it would be useful for discriminating between segregating lines.)

[joseph]

Very easy to test for carotenes at home with commonly available materials.

Extract the pigments with a solvent.
Run a paper chromatography test.
If you keep the concentrations of your tests consistent, you would be able to dry the test strips, and compare them one against another to determine which has the highest concentration of carotenes.

You could even make it semi-quantitative by using β-carotene vitamin pills to make control solutions of known concentration.

For example: http://www.hsu.edu/pictures.aspx?id=1653 will give you ideas about what keywords to search for additional details. "Paper chromatography carotenoids" is a great search term.

[ChrisK]

Joseph is correct. Paper chromatography is a good way to separate plant pigments and can be done easily, it was one of the favorite lab exercises I used to teach. Making it quantitative will require some work and careful measurement. You should be able to get relative differences if not an absolute quantities. if you can get your hands on real chromatography paper that would be best. I would also recommend a dot instead of a line of extracted pigment, the smaller the better.

Depending on how fancy you want to get, old spectrometers can be found on Ebay for a couple hundred dollars...would be able to do quantitative analysis easily.

The attached doc is not mine but is a reasonable overview of the process.

[crmauch]

Thanks! This is the kind of start I'm looking for.

Chris

[Fusion_power]

You might start by finding the variety 97L97 which is a 40X carotene variety.

DarJones

[tlintx]

Just googling the terms in this thread has made me smarter. Not that that's saying much, but still.

Would a "spectroscope" work for this purpose? Or does it have to be a spectrometer?

Also... it's truly amazing what you can buy on Amazon in the Industrial & Scientific section.

[Fusion_power]

To get really accurate results would require a gas chromatograph. Fortunately, it is not necessary to get that detailed, a recent study showed that visual examination can lead to significant genetic gain when selecting for lycopene which just happens to be a red carotenoid.

[tlintx]

Interesting, so you'd basically be looking for the orangest, most carrot-colored (or reddest, for lycopene) tomato you could get. In that case, could you use a digital camera plus color balance strip to make photos to compare to other attempts? Maybe use the one you referred to earlier and a carrot as reference points?

Thinking "cheap" and "no volatile chemicals" here.


Tl

[joseph]

I am breeding for high carotene corn and butternut squash. A visual test is sufficient. Of course I don't have red lycopene interfering with my color tests.

[crmauch]

Originally Posted by joseph

I am breeding for high carotene corn and butternut squash. A visual test is sufficient. Of course I don't have red lycopene interfering with my color tests.

Plus you can get orange by more than one path.

But your corn is beautiful, as I remember, a local museum (Landis Valley) sold a form of popcorn that appeared 'pre-buttered'. I like your squash as well, however, as I'm the only one in my family who likes squash, I only inflict a small amount on them.

[crmauch]

Originally Posted by tlintx

Interesting, so you'd basically be looking for the orangest, most carrot-colored (or reddest, for lycopene) tomato you could get. In that case, could you use a digital camera plus color balance strip to make photos to compare to other attempts? Maybe use the one you referred to earlier and a carrot as reference points?

I would have thought this too, however in doing online 'research' I've found that not all orange tomatoes are created equal. Anything in the 'yellow' to white (often noted as r) reduces all carotenoids.

There is an 'Apricot' gene (noted as at) that seems to show a very slight increase in beta-carotene.

There is a 'tangerine' gene (noted as t) that has reduced beta- and and increase in something called zeta-carotene (and other different carotenoids

And there is Del which has 'normal' beta but much increase delta-carotenoid (I can find information about beta (of course) and have found out that alpha carotenoid is considered 'half' as effective for conversion to vitamin A, but there doesn't appear to be any information on whether delta-carotenoid can be converted to vitamin A in the body.

The article about breeding these is here: http://www.genetics.org/content/62/4/769.full.pdf

There is another article about breeding with B (high beta-carotene) and Del here:
http://www.genetics.org/content/56/2/227.full.pdf

However there doesn't appear to be articles about breeding these newer very high carotene tomatoes with both B and MOG [the G should be subscripted] and how they interact with the other 'orange' genes. An article about the USDA introduction of breeding stock with these high carotene genes notes that B (which is dominant) and the dominant form of the linked modifier gene MOG+ reduces beta-carotene from 90% of the carotenoids to 50-60% and increases lycopene to less than 50% giving red-orange tomatoes. That article is here: http://hortsci.ashspublications.org/...2/387.full.pdf

The 'safest' way (it seems to me) to preserve high beta would be to breed the high betas only to red (or pink) varieties, and select them back to orange.

[joseph]

The other thing that might work well is a set of standard color strips like you might find at a paint store, or on the back of the box for a pool test kit.

[tlintx]

Or you could eat twice as much of the super 40x beta carotene tomato Fusion mentioned above.

Beats liver any day!

[Fusion_power]

There is a possibility that I can get a Del tomato to sell plants for next year. I'll see what can be done.

Meantime, look up "Stommel carotene" if you want to read about some interesting breeding work.

As an fyi, ramping up beta carotene has a drastic impact on flavor.

[joseph]

Originally Posted by Fusion_power

As an fyi, ramping up beta carotene has a drastic impact on flavor.

I haven't played with high carotene tomatoes, but I've certainly noticed improved flavor in muskmelons, squash, and carrots due to higher carotenes.