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Post by gilbert on Jan 13, 2018 10:44:38 GMT -5
There are high oleic varieties of sunflower available, in which the bulk of the oil produced is monounsaturated instead of polyunsaturated. It seems the available varieties are all commercial hybrids. So, to develop an open pollenated strain that expressed this (invisible) trait, how would one proceed?
More generally, how would one breed for any non-obvious nutritional characteristics? I'm sure one could do lab tests, but tests on each individual would be almost impossible, and in the case of sunflower, only possible after seed set, at which point it would be too late to eliminate undesirable pollen donors.
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Post by walt on Jan 13, 2018 14:53:06 GMT -5
While wild sunflowers are almost all self incompatible, and OP domestic also, the rare (origionally) self compatible sunflowers have been selected and bred from so inbreds can be made, and from them F1 hybrids can be made.
So all those high oleic sunflowers are self cfompatible
So a breeder will self a bunch of sunflowers and test them at maturity. Those with higher oleic content are intercrossed and the cycle repeated.
If you want an OP high oleic sunflower, intercross some high oleic hybrid varieties and you have a high oleic OP variety. I guess you could just do one hybrid variety and have an OP variety, but it would be highly inbred. But sunflowers do tolerate inbreeding better than most self incompatible crops.
In the F2 there will be some male sterility, but that will decrease over genertions.
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Post by gilbert on Jan 13, 2018 15:12:52 GMT -5
Would the segregating material from such a selfing include low oleic types? If so, would they dominate over time? Which would confer a greater advantage, monounsaturated or polyunsaturated fats? There must be some reason almost all temperate plants have polyunsaturated oils, while tropical ones have mono or saturated types . . .
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Post by tpeltan on Jan 14, 2018 14:25:38 GMT -5
There are high oleic varieties of sunflower available, in which the bulk of the oil produced is monounsaturated instead of polyunsaturated. It seems the available varieties are all commercial hybrids. So, to develop an open pollenated strain that expressed this (invisible) trait, how would one proceed? More generally, how would one breed for any non-obvious nutritional characteristics? I'm sure one could do lab tests, but tests on each individual would be almost impossible, and in the case of sunflower, only possible after seed set, at which point it would be too late to eliminate undesirable pollen donors. From this paper www.researchgate.net/profile/Juan_Dominguez10/publication/226137656_Genetic_analysis_of_the_high_oleic_acid_content_in_cultivated_sunflower_Helianthus_annuus_L/links/0deec5368c063654c9000000.pdf it seems the high oleic acid is based on the genotype of the seed, not the maternal plant. The paper suggests you can directly choose the desired seed (but you need the laboratory). See the end of the paper. |
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Post by gilbert on Jan 15, 2018 15:03:19 GMT -5
I bought two different kinds of sunflower oil; one a high oleic type with 11g of monounsaturated fat per tablespoon, the other a standard type with 3 grams. The standard type has half a gram more of saturated fat, which could skew the following test . . . in any case, I'm putting them both in the refrigerator, to see if the difference is obvious.
If it is, all I'd need to do is save each sunflower head separately, press 3/4 of the seeds from each, and put them in the refrigerator. Then I'd plant the remaining seeds from the heads that solidified best.
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Post by walt on Jan 15, 2018 15:12:06 GMT -5
I look forward to hearing your results.
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Post by gilbert on Jan 15, 2018 16:58:58 GMT -5
I just skimmed through the paper tpeltan posted; thanks for that!
Two things stand out, if I'm understanding it correctly; there are three genes controlling oleic content, with high oleic being dominant in each; and, the seed oleic content is determined by the embryo genotype, not the maternal genotype. This would make my suggested procedure above less effective, but would it make it totally ineffective?
Let's say I made an initial cross (or started with a commercial hybrid) and planted out the F1 seed. The F1 seeds would all be high oleic. The F2 seeds would start segregating out. However, would a head in which the maternal genotype was homologous for oleic content produce a higher percentage of seeds with a high oleic genotype (and thus expression) than one in which it was not?
If I kept selfing a bunch of lines from an initial cross, in each case saving seed from the heads with the highest oleic content as shown by the oil from 3/4 of the seeds hardening at low temperatures, would I eventually establish a number of strains that would be homologous for this trait? I could then let these strains mass cross to restore diversity and vigor to the population.
I'm no expert at genetics, and would appreciate some advice.
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Post by tpeltan on Jan 16, 2018 13:35:01 GMT -5
I just skimmed through the paper tpeltan posted; thanks for that! Two things stand out, if I'm understanding it correctly; there are three genes controlling oleic content, with high oleic being dominant in each; and, the seed oleic content is determined by the embryo genotype, not the maternal genotype. This would make my suggested procedure above less effective, but would it make it totally ineffective? Let's say I made an initial cross (or started with a commercial hybrid) and planted out the F1 seed. The F1 seeds would all be high oleic. The F2 seeds would start segregating out. However, would a head in which the maternal genotype was homologous for oleic content produce a higher percentage of seeds with a high oleic genotype (and thus expression) than one in which it was not? If I kept selfing a bunch of lines from an initial cross, in each case saving seed from the heads with the highest oleic content as shown by the oil from 3/4 of the seeds hardening at low temperatures, would I eventually establish a number of strains that would be homologous for this trait? I could then let these strains mass cross to restore diversity and vigor to the population. I'm no expert at genetics, and would appreciate some advice. If I understood the paper well you can select the F2 genotypes with the seed from F1 plants (without planting it) - you will be one step ahead and include the influence of both F1 parents. While this will be very effective, selecting the F1 plants based on the oil of its seeds should also help you to reach your aim. |
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Post by gilbert on Jan 16, 2018 14:14:35 GMT -5
The oils in the refrigerator don't show any differences so far. I might have to try them in the freezer.
I've just found that some sunflower strains have also been bred to have high saturated content, which is interesting.
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Post by gilbert on Jan 16, 2018 14:15:49 GMT -5
That's good. I don't have the ability to test individual seeds; I'd guess that would need a fairly substantial lab setup.
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Post by gilbert on Jan 16, 2018 21:45:57 GMT -5
Both oils froze solid in the freezer. The monounsaturated oil was slightly thicker in the refrigerator, but it wouldn't be an easy difference to see in small test amounts of oil. I guess I'd have to find a different test. I'm sure there must be something out there.
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Post by gilbert on Jan 16, 2018 22:44:21 GMT -5
Looks like I could use a procedure with iodine; but this would only give me an idea of how many unsaturated bonds there were compared to saturated, not a clear breakdown between mono and poly, and in any case, doing it properly would involve chloroform! vlab.amrita.edu/?sub=3&brch=63&sim=1111&cnt=2There has to be a better way . . . |
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Post by tpeltan on Jan 17, 2018 13:23:46 GMT -5
Both oils froze solid in the freezer. The monounsaturated oil was slightly thicker in the refrigerator, but it wouldn't be an easy difference to see in small test amounts of oil. I guess I'd have to find a different test. I'm sure there must be something out there. How fast? Can you change the setting of the freezer (lower or higher temperature)? I have stored olive oil in refrigerator some time ago and after some time it started to slowly (i.e months) change to solid state (with continuous creation of small solid pieces). |
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Post by gilbert on Jan 17, 2018 14:04:42 GMT -5
They were both solid within a few hours. I guess I could time them next time.
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andyb
gardener
Posts: 179
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Post by andyb on Jan 18, 2018 0:01:47 GMT -5
A styrofoam cooler filled with water should have a very stable temperature and a lot of thermal mass. You could adjust it from sub-freezing (salty icewater) to absolutely stable 0C (icewater) to whatever > 0C temperature you wanted. Cheap, too.
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