Author Topic: increasing the outbreeding rate  (Read 391 times)

Ocimum

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increasing the outbreeding rate
« on: 2020-06-24, 01:41:48 AM »
In many crops, both inbreeding and outbreeding happen. For example in lentils, which are mostly pollinated before the flowers open.

Therefore, if one plant has 20% outbreeding and the other plant has 0% outbreeding rate, the plant which does not outbreed will (all other things being equal) leave more offspring, because its pollen can still be used on the other plant.

Disregarding evolutionary advantages of outbreeding and recombination in times of environmental stresses, the rate of outbreeding should therefore go down in the population.

How can we work around this, in a way to increase the outbreeding in the crops?

What is already done by the promiscuously pollinated tomato project is working with self incompatibility and flower morphology (exerted stigma).
 
Something else which could be done, for example in lentils?

reed

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Re: increasing the outbreeding rate
« Reply #1 on: 2020-06-24, 03:30:15 AM »
I'm not at all familiar with lentils. Are they at all similar to common beans in their crossing rate? Do bees visit their flowers?
I ask cause I'm finding that crossing in beans is pretty common just by planting them all mixed up.

Ocimum

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Re: increasing the outbreeding rate
« Reply #2 on: 2020-06-24, 04:16:23 AM »
yes, from 0-5 % outcrossing, I think the same as in beans.

Maybe my message wasn't formulated well: I am asking how to increase the outbreeding rate of the crop itself. In a way that by planting them mixed up, instead of getting 2% outcrossing, I get 8%, without altering the environment.

Daniel C.

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Re: increasing the outbreeding rate
« Reply #3 on: 2020-06-24, 04:36:17 AM »
Simply by selecting the crosses you will be selecting for outbreeding, I would think

Andrew Barney

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Re: increasing the outbreeding rate
« Reply #4 on: 2020-06-24, 06:04:30 AM »
This may not be the answer you are really looking for,  but I've found that by simply growing more pea varieties consistently each year and planting them in close proximity with many or most of them having bright colorful wild type flowers the native solitary bees that visit them has gone up and this has led to much more out crossing than what is typical for self pollinating peas. Leaf cutter bees that would typically visit alfalfa and clover plants are the ones visiting the peas the most.

I am now also growing a mutated pea variety that has open keels which in theory might outcross more.
« Last Edit: 2020-06-24, 06:07:20 AM by Andrew Barney »

Ocimum

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Re: increasing the outbreeding rate
« Reply #5 on: 2020-06-24, 07:19:29 AM »
Andrew: thanks for the keyword color, it led me to this paper

https://link.springer.com/article/10.1007/s10681-009-9953-0

Quote
To optimize the balance between high yielding varieties and those that support pollinator conservation, the identification of desirable floral phenotypes is crucial. It is necessary to focus on traits associated with CPR, such as floral attractiveness, in terms of colour, design, display, and phenology, and rewards, both of pollen and nectar, which are often beyond the objectives of most legume improvement programs.


Andrew Barney

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Re: increasing the outbreeding rate
« Reply #6 on: 2020-06-24, 09:35:27 AM »
Andrew: thanks for the keyword color, it led me to this paper

https://link.springer.com/article/10.1007/s10681-009-9953-0

Interesting paper!

Yeah,  in some ways this is exactly what Joseph is focusing on in tomatoes other than exerted stigmas. More pollen shed, larger flowers,  darker petals, darker anthers.

I want to find an easy way to look at flower UV bands that only pollinators can see.

Joseph Lofthouse

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Re: increasing the outbreeding rate
« Reply #7 on: 2020-06-24, 04:49:20 PM »
When I look at lagenaria squash under shortwave UV light after dark, the flowers are very reactive to the light.


Joseph Lofthouse

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Re: increasing the outbreeding rate
« Reply #8 on: 2020-06-24, 05:20:49 PM »

What I think I observe, is that families with flowers that are all closed up, so as to have a 0% crossing rate become inbred, and thus is less viable.  They tend to neither give nor receive pollen, and therefore get continuously more inbred, and continuously less productive.

Any varieties that have some small cross pollination rate produce some hybrids. Some of the hybrids fail, and others thrive much more than either parent. A plant that is thriving produces more seeds, and since offspring tend to resemble their parents and grandparents, they tend to be slightly more out-crossing. And the families that are slightly more out-crossing have a reproductive advantage because of ongoing hybrid vigor.

I'm breeding wheat and barley this year. If I really wanted to select for promiscuity, I could monitor the patch closely, and select inflorescences that have anthers outside of the glumes. Anthers mostly remain inside the glumes, leading to the high selfing rate of wheat and barley. I have observed some flower head with about 40 anthers outside the glumes. Different varieties don't have any exposed anthers.

Careful, frequent, thoughtful observation can be time consuming and tedious, but it can sure help with identification of more promiscuous types of flowers, and more out-crossing families.



Ocimum

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Re: increasing the outbreeding rate
« Reply #9 on: 2020-06-25, 01:38:40 AM »
Thanks for the messages.

Below a paper on Vicia faba, which states that inbred plants have more outcrossing, and heterozygous plants have more self-fertility.

https://sci-hub.tw/https://www.nature.com/articles/177489b0

reed

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Re: increasing the outbreeding rate
« Reply #10 on: 2020-06-25, 03:29:52 AM »
I have never studied or tracked well enough to know it for sure but I think crossing in beans is probably higher than 5%. I didn't used to grow as many as I do now and we used them mostly as green beans so I rarely found any crosses in the seeds I saved.

Now that I've increased my planting 10 fold and mostly for dry use I find crossed beans all the time. The bumblebees are very active on bean flowers, they tear and pry them open. I would almost bet that if one plant of variety A was planted on the same pole as one of variety B  so that the flowers of the two are intermingled some of each would be crossed. Of course there is no way to know which ones until they are grown out the next year and of course lots of them end up in bean soup before then.

But given for example, you have 20 pounds of beans, and 19 pounds are eaten in soup but you still find crosses when you grow out the other pound makes me think crossing is pretty common.

I also find crosses in commercial seeds. For example when I grew a pack of NT 1/2 runners from Sustainable Mountain Agriculture I found crossed seeds. Same when I grew a pack of Blue Lake from Park's. Both of those are normally for use as green beans so normally those crosses would never be found but I wanted a good supply of seed and grew them expressly for that.

Maybe purposely planting the successive generations of know crosses when I first got interested in such things increased the trait in my mix. Maybe too some of what I think are new crosses are really just  segregates from prior ones, I just don't know.

 
« Last Edit: 2020-06-25, 03:40:08 AM by reed »

William S.

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Re: increasing the outbreeding rate
« Reply #11 on: 2020-06-26, 09:50:55 AM »
It is sure working well for tomatoes as a strategy. Is it applicable to all crops or even all plant species?

With many plant species increasing pollinator presence may help. Potentially even for wind pollinated species. Even insect presence period. In one of the one straw revolution books it was noted that grasshoppers opened rice heads and lead to crossing. Pollinators rob pollen from wind pollinated species. Evolutionarily there is a pathway there. Then within pollinator complexes there are obligate pollen and nectar robbers. Ants and beetles that chew through plant flower parts. This can lead to cross pollination in selfie species. If there is an evolutionary disadvantage to selfish after a point, occasional insect mediated pollination may solve that for some plant species. The thing is we aren't all gifted with the same pollinator complex. Though by gardening without anything which could affect pollinators and by intentionally raising lots of pollinator plants, partucularly a wide diversity of native plants we can embellish the pollinator complexes we do have. Then I think it can just be important that we do this work collaboratively. You never know who has the right environmental conditions for open pollination in a grain or the right insect to chew it open at the right time.
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Lauren

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Re: increasing the outbreeding rate
« Reply #12 on: 2020-06-29, 01:52:11 PM »
One thing I've noticed specifically with dry beans is that if the parents are dissimilar enough I can often see variations in the first generation seeds--orange seeds planted next to scarlet, the progeny were mottled with the two colors. Rattlesnake planted next to Hopi red, some of the rattlesnake progeny ended up red while some of the Hopi had the distinctive patterning of the rattlesnake. So I pulled those aside for my next generation.
« Last Edit: 2020-07-05, 07:48:00 PM by Lauren »

reed

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Re: increasing the outbreeding rate
« Reply #13 on: 2020-07-05, 03:52:22 PM »
I have a few kinds of beans that I keep pure because the woman here prefers them for canning green beans so when I save seed from them I notice right away if there are any off types.

In my dry bean mixes though unless something really stands out as different I probably never even notice it. Last year for example I found some large rather flat pink colored beans. They are different from any I planted or really ever seen before. They are growing out there right now a little bit separated from the others so I can have fun seeing how they segregate out. I find I usually get round six different kinds from the F2 seeds and usually there is one that looks just like the F1.

There actually might be even more than six especially if you grow lots of the F2 but differences in the plants themselves other than seed size, shape or color are much harder to notice.