Daylilies forum: Dominant, recessive, additive characteristics

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Name: Maurice
Grey County, Ontario (Zone 4b)
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admmad
Jul 20, 2015 9:34 AM CST
A simplified explanation of the classical genetic terms dominant, recessive and additive.

I am going to use diploids in my examples because classical (Mendelian) genetics (that many of us learned) usually do not apply as well to tetraploids.

If one of the parents of a cross has/shows a particular characteristic and the seedlings also show the characteristic then generally that characteristic is described as the dominant characteristic in comparison to the alternative characteristic. For example, I cross 'Pardon Me' with 'Gentle Shepherd' and I find that all the seedlings have red flowers. If all the seedlings are the same red colour as their 'Pardon Me' parent then red flower colour is dominant to white flower colour. White flower colour would be recessive to red flower colour.

Now if I take two of the seedlings from the cross 'Pardon Me' x 'Gentle Shepherd' (and both have the same red flower colour as their 'Pardon Me' parent) and I cross them with each other [red flower x red flower] I will find that some of those seedlings are red-flowered and some are white-flowered and I would describe white flower as recessive to red flower colour. However, it is very important to know that I do not expect many of those seedlings to have white flowers, in fact only one in four, on average would be white-flowered. And I could easily grow as many as eleven seedlings to flowering and not find a white-flowered seedling. Genetics is a numbers game and to be reasonably certain of finding certain characteristics in crosses one needs to grow sufficient seedlings.

If both parents of a cross must show the same characteristic for the seedlings to show the characteristic then that characteristic would be described as recessive to its alternative. If I cross 'White Temptation' with 'Gentle Shepherd' and all the seedlings are white-flowered like their parents then white flower is recessive.

If both parents of a cross show the same characteristic, say gold edges, and the seedlings show the same characteristic but in a more extreme form then the characteristic would be described as additive. In this case perhaps the gold edges are more pigmented or they are wider or they cover more of the petal edges, etc. The catch with additive characteristics is that there may be so little that the characteristic is not visible to our naked eyes in either parent yet when combined in the seedlings there is then enough of an effect that it becomes visible to us.

Most characteristics in daylilies (even in diploids) are not inherited in simple classical Mendelian ratios. Dominant characteristics are rarely the same in offspring and parents. They are partially dominant or there are many genes that affect each characteristic so that they are better described as additive rather than dominant or recessive.

In tetraploids, even in very simple situations where a characteristic is simply inherited in the diploid, the situation may typically be additive. In a diploid, WW might be red-flowered, Ww might have the same red flower and ww might be white-flowered yet the tetraploid versions might be WWWW dark red, WWWw red, WWww medium red, Wwww light red and wwww white flowered - better described as additive or possibly partially dominant.
Maurice
Name: Becky
Sebastian, Florida (Zone 10a)
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beckygardener
Jul 20, 2015 11:31 AM CST
Maurice - Very easy to understand lesson on dominate, recessive, and additive! Thank you for always explaining these concepts in a much simpler way to understand for folks like me who are not science-minded. I can certainly see the point about "additive". I had never heard that term until now.

I do have a question about something you mentioned in your lesson ...

You wrote, "If I cross 'White Temptation' with 'Gentle Shepherd' and all the seedlings are white-flowered like their parents then white flower is recessive."

Why would it be recessive? I would have expected the white trait to be dominant since both parents were white flowered.
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[Last edited by beckygardener - Jul 20, 2015 11:40 AM (+)]
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Name: Maurice
Grey County, Ontario (Zone 4b)
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admmad
Jul 20, 2015 12:16 PM CST
beckygardener said:You wrote, "If I cross 'White Temptation' with 'Gentle Shepherd' and all the seedlings are white-flowered like their parents then white flower is recessive."
Why would it be recessive? I would have expected the white trait to be dominant since both parents were white flowered.

It is not usually possible to definitively classify a characteristic as dominant/recessive/additive/etc. from the observations of only one cross. So one must examine the results of several different kinds of crosses to determine how a characteristic might be inherited.

In the case of red flowers and white flowers in my example first a red flowered plant was crossed with a white flowered plant and all the seedlings were red coloured. Only one parent needed to be red and even though the other parent was white all the seedlings were red flowered. Two of those red flowered seedlings were crossed together and some of their seedlings were red flowered and some were white flowered. Finally two white flowered plants were crossed with each other and all their seedlings were white flowered. Both parents had to be white flowered for all their seedlings to be white flowered. One needs to look at the results of all three of the different types of crosses to determine how red and white flowers are inherited.

More of the example. If I only cross 'Pardon Me' with another red flowered plant (I make no other crosses) and all the seedlings are red-flowered I cannot tell whether red flowers is a dominant characteristic or a recessive characteristic. If I only cross 'White Temptation' with 'Gentle Shepherd' and all the seedlings are
white flowered I cannot tell whether white flowers is a dominant characteristic or a recessive characteristic. I have to make crosses between red flowered plants and white flowered plants and usually I also have to make crosses with the seedlings so produced to get a good idea about how those two flower colours are inherited.

In fact, the classical test for determining how characteristics are inherited is to cross two individuals to produce the F1 seedlings. Then to cross two of those F1 seedlings with each other to produce the F2 seedlings (or usually to self-pollinate one of the F1 seedlings) and to cross one of those F1 seedlings back to one parent and another of those F1 seedlings back to the other parent. Finally, if one wants to complete the analysis one would take some of the F2 seedlings showing the different parental characteristics and self-pollinate them.

Even in the simplest Mendelian case I could have the following types of crosses (red flower is dominant to white flower, white flower is recessive to red flower):
red flowered x red flowered producing all red flowered seedlings
red flowered x red flowered producing red flowered and white flowered seedlings
red flowered x white flowered producing all red flowered seedlings
red flowered x white flowered producing some red flowered and white flowered seedlings
white flowered x white flowered producing all white flowered


Maurice
Name: Becky
Sebastian, Florida (Zone 10a)
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beckygardener
Jul 20, 2015 12:58 PM CST
Maurice - I understand "the simplest Mendelian case". But I may be misunderstanding what you wrote previously or taking your example too literally ....

I looked up in the Plant Database both cultivars you used in your example (perhaps I was being too literal here?)

White Temptation and Gentle Shepherd both show "sdlg x sdlg" for parentage. I don't know any other information about their genetics other than what the AHS database and the PlantFiles Database wrote. Perhaps you know more. Anyway, I also looked at the children that each cultivar has produced. Most children are light yellow/near-white bloomers.

That is where my confusion about dominant vs. recessive comes in. Why would any white blooming children be considered a recessive gene if both parents are near-white and most of their other children seem to have near-white blooms (depending on what they were crossed with)? What would you consider to be their dominant color?

Perhaps I am just taking your example too literal. I am a visual person, so I like to research and SEE the bloom to get a better idea than just reading a description of the bloom. This is why my confusion.
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Name: Maurice
Grey County, Ontario (Zone 4b)
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admmad
Jul 20, 2015 2:51 PM CST
beckygardener said:That is where my confusion about dominant vs. recessive comes in. Why would any white blooming children be considered a recessive gene if both parents are near-white and most of their other children seem to have near-white blooms (depending on what they were crossed with)? What would you consider to be their dominant color?


I think perhaps it is that there is no "their dominant color" of the seedlings.

Dominant and recessive describe specific alternatives of specific characteristics but not of specific seedlings or of specific individual plants.

Flower colour is the specific characteristic for the example. The flower colours red and white are the specific alternatives for that characteristic for the example.

So, flower colour is a specific characteristic. The overall colour of a daylily flower is made by a set of genes that function in a long pathway with each step controlled by a different gene and all the genes required to be normal and to function correctly for the flower to have a normal colour. The end result of a properly working pathway or assembly line is a pigment of a particular colour that is present in the flower. For the sake of these examples we can assume that the normal daylily flower is reddish (like the ditch lily species) and that the normal pigment is red. In our example, (please do not be too literal here as the example is not meant to be looked up in the AHS database nor are the registered offspring important) the alternative is no pigment or white flowers. In our example daylily flowers can be red or they can be white. One of those characteristics can be dominant and one can be recessive. If one is dominant then the other is recessive. Or the characteristics can be additive and neither is dominant or recessive.

Once we have made all the necessary different types of crosses between red flowered and white flowered daylilies and tabulated and analyzed the types of seedlings produced we can decide if red is dominant or if white is dominant or whether they are additive (and so on). Once that has been determined then the decisions are more or less permanent and apply to all crosses involving red and white flowered plants. We would always describe red flower colour as dominant to white flower colour. Across of two white flowered plants would be predicted to produce only white flowered seedlings because white flower colour was discovered to be inherited recessively.

Maurice
Name: Becky
Sebastian, Florida (Zone 10a)
Celebrating Gardening: 2015 Daylilies Hummingbirder Butterflies Seed Starter Container Gardener
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beckygardener
Jul 20, 2015 4:24 PM CST
Maurice - So basically the majority of our hybrid daylilies came from red/orange ditch lilies (fulva), correct? Which would make THAT color the dominant genetic color, correct? So that would indeed make a light yellow/near white daylily color recessive, not dominate. Or as you also said ... at the very least, it would make it an additive.

So for fulva descendents, the dominant color is always red?

Now what about a different species daylily like citrina with yellow blooms? If it was crossed with another, would the dominate color then be yellow for any seedlings?

I am trying to wrap my brain around dominant/recessive vs. the color being a specific characteristic. Is it that a particular daylily when crossed will often throw a specific color or pattern or ruffles or teeth? If that shows up in most of the seedlings, it is considered a dominate trait? And recessive is the opposite in that it can show up but not as often or as likely?
What lies behind us and what lies before us are tiny matters, compared to what lies within us.
Garden Rooms and Becky's Budget Garden
Name: Maurice
Grey County, Ontario (Zone 4b)
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admmad
Jul 20, 2015 6:14 PM CST
beckygardener said:So basically the majority of our hybrid daylilies came from red/orange ditch lilies (fulva), correct?

Many different species were used by Stout and the early hybridizers to produce the early cultivars. It is difficult to determine whether any single species could be described as being responsible for the majority of the original hybrids. A genetic overview analysis of the species and a number of cultivars did not find the ditch lily as being particularly similar to the early cultivars.

Which would make THAT color the dominant genetic color, correct? So that would indeed make a light yellow/near white daylily color recessive, not dominate. Or as you also said ... at the very least, it would make it an additive.

So for fulva descendents, the dominant color is always red?

Now what about a different species daylily like citrina with yellow blooms? If it was crossed with another, would the dominate color then be yellow for any seedlings?

Sorry, no. There is no relationship between different species and whether a particular value for a characteristic is dominant or recessive. That is, if red flower colour is dominant to yellow then it will simply always be dominant to yellow flower colour. If red flower colour is dominant to white flower colour then it will always be dominant to white flower colour.

I am trying to wrap my brain around dominant/recessive vs. the color being a specific characteristic. Is it that a particular daylily when crossed will often throw a specific color or pattern or ruffles or teeth?
Sorry, no. Identifying which of the alternative values for a characteristic is dominant or recessive does not depend on the breeding behaviour of particular daylilies but on the breeding patterns shown by all daylilies for that characteristic.
If that shows up in most of the seedlings, it is considered a dominate trait?
Sorry, no. Whether a specific value for a characteristic is dominant or recessive is determined by the results of specific crosses (the F1, F2, both backcrosses to the parents and the test of F3 families).
And recessive is the opposite in that it can show up but not as often or as likely?
Sorry, no. The recessive characteristic must show up in the expected proportions in the appropriate crosses in the test (see above) and not show up in the other crosses.

Maurice
Name: Becky
Sebastian, Florida (Zone 10a)
Celebrating Gardening: 2015 Daylilies Hummingbirder Butterflies Seed Starter Container Gardener
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beckygardener
Jul 20, 2015 9:16 PM CST
Maurice - Oh geez! I am obviously misinterpreting the meaning of the words: "dominant" and "recessive" in regards to genetics. Sighing!

I must of failed that part in Biology. Sad

I don't know why I am not fully understanding this. I think of the verb word "dominate" in the context of:
http://dictionary.reference.com/browse/dominate

Instead of Dominant as a noun:
http://dictionary.reference.com/browse/dominant?s=t

Quoted as:
" noun
Genetics.

the one of a pair of alternative alleles that masks the effect of the other when both are present in the same cell or organism.
the trait or character determined by such an allele.
Compare recessive."

Recessive:
http://dictionary.reference.com/browse/recessive

Quoted as:
noun, Genetics.

that one of a pair of alternative alleles whose effect is masked by the activity of the second when both are present in the same cell or organism.

the trait or character determined by such an allele.
Compare dominant.

I seem to have a mental block about this for some reason .....
What lies behind us and what lies before us are tiny matters, compared to what lies within us.
Garden Rooms and Becky's Budget Garden
[Last edited by beckygardener - Jul 20, 2015 9:17 PM (+)]
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Name: Becky
Sebastian, Florida (Zone 10a)
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beckygardener
Jul 20, 2015 10:18 PM CST
Is "red" the dominant color for ALL daylilies?
What lies behind us and what lies before us are tiny matters, compared to what lies within us.
Garden Rooms and Becky's Budget Garden
[Last edited by beckygardener - Jul 21, 2015 12:30 AM (+)]
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Name: Maurice
Grey County, Ontario (Zone 4b)
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admmad
Jul 21, 2015 6:41 AM CST
beckygardener said:Is "red" the dominant color for ALL daylilies?

Formally, scientifically, no one has made the necessary crosses with daylilies to determine how any of the flower colours are inherited in diploid daylilies or in tetraploid daylilies. So we cannot formally (and with any great confidence) say whether "red" flower colour is dominant but if it is, then it is dominant for ALL daylilies (but see below for purple).

We also have the problem of the flower colour "purple".

In general and as a very over-simplified explanation, excluding purple, red is more or less dominant to the other colours.
In general and as a very over-simplified explanation, excluding red, purple is more or less dominant to the other colours.

If red flowered and purple flowered diploid daylilies are crossed with each other we might find that red and purple are additive (or sometimes possibly described as co-dominant or possibly incompletely dominant).

However, there are more complications in daylilies in that crosses of red flowered daylilies with yellow flowered daylilies may produce seedlings that are not actually described as red flowered but may be described as "brown" or "muddy" or "drab", etc. The same may be true for crosses of purple flowered daylilies with yellow flowered daylilies.

Mendel's research was very exact and he used a species (the pea) that allowed relatively simple conclusions about inheritance. Unfortunately diploid daylilies are probably one of the worst species to use for genetics (especially in the home garden) because they are generally self-incompatible and tetraploid genetics are much more complicated than diploid genetics.
Maurice
Name: Becky
Sebastian, Florida (Zone 10a)
Celebrating Gardening: 2015 Daylilies Hummingbirder Butterflies Seed Starter Container Gardener
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beckygardener
Jul 21, 2015 9:34 AM CST
Maurice - Thank you for your extreme patience in trying to clue me in about all of this. I did not know that most dips are self-incompatible. I do know that tets are quite complicated genetically, but boy are they fun to hybridize! Big Grin

Being the visual person that I am, I searched on YouTube for a video about Mendel's pea plant experiment. I found this video, which entertained me with a few laughs too. Is this video accurate in relevance to Mendelian genetics?:

https://www.youtube.com/watch?v=Mehz7tCxjSE
What lies behind us and what lies before us are tiny matters, compared to what lies within us.
Garden Rooms and Becky's Budget Garden
[Last edited by beckygardener - Jul 21, 2015 9:35 AM (+)]
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Name: Becky
Sebastian, Florida (Zone 10a)
Celebrating Gardening: 2015 Daylilies Hummingbirder Butterflies Seed Starter Container Gardener
Charter ATP Member I was one of the first 300 contributors to the plant database! Garden Ideas: Master Level Lover of wildlife (Black bear badge) Birds Ponds
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beckygardener
Jul 21, 2015 9:37 AM CST
This is probably a more formal and detailed explanation on video:

https://www.youtube.com/watch?v=NWqgZUnJdAY
What lies behind us and what lies before us are tiny matters, compared to what lies within us.
Garden Rooms and Becky's Budget Garden
Name: Maurice
Grey County, Ontario (Zone 4b)
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admmad
Jul 21, 2015 9:57 AM CST
beckygardener said:Maurice - Thank you for your extreme patience in trying to clue me in about all of this.

You are most welcome.

Being the visual person that I am, I searched on YouTube for a video about Mendel's pea plant experiment. I found this video, which entertained me with a few laughs too. Is this video accurate in relevance to Mendelian genetics?


Both videos are fine describing Mendel's findings.
Maurice
Name: Becky
Sebastian, Florida (Zone 10a)
Celebrating Gardening: 2015 Daylilies Hummingbirder Butterflies Seed Starter Container Gardener
Charter ATP Member I was one of the first 300 contributors to the plant database! Garden Ideas: Master Level Lover of wildlife (Black bear badge) Birds Ponds
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beckygardener
Jul 21, 2015 5:26 PM CST
I "think" I understand the dominant / recessive concept now. Confused Whistling Thumbs up
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