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 - 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.

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 - 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.

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 - 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?

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 - Oh geez! I am obviously misinterpreting the meaning of the words: "dominant" and "recessive" in regards to genetics.

I must of failed that part in Biology.

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.co...

Instead of Dominant as a noun:
http://dictionary.reference.co...

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.co...

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 .....

Is "red" the dominant color for ALL daylilies?

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 - 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!

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?...

This is probably a more formal and detailed explanation on video:

https://www.youtube.com/watch?...

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.

I "think" I understand the dominant / recessive concept now.

Hi
I know it's of the Daylillies subject but the principles remain the same, hopefully.

This is one of my hybrids.

This is a photo of JHC L1 Choir Mistress under different lighting conditions.

This is a seedling from the same cross shown in the "Tree"
-
Would I be right in suggesting co-dominance mediated by another gene? Or is incomplete dominance playing a part?

The Pink flower is definitely the result of co-dominance?

Cheers

@ausrpned
It is difficult to know what is happening genetically without more details.
1) What species are the plants?
2) Are they diploids, tetraploids or something else?
3) For any cross, what did all the other seedlings look like? What do the seedlings look like from other crosses?

The concepts of dominant (and recessive), codominance and incomplete dominance work best when the crosses are between inbred lines and in particular inbred lines that differ only in the same characteristic - that is, they have been made genetically identical except for that one characteristic. When the crosses are between two completely different lines (or strains, etc.) it becomes much more difficult to assign a simple label. Without more information, particularly what do the other seedlings from the same crosses look like, it is not possible to provide an explanation with reasonable confidence.

admmad said:@ausrpned
It is difficult to know what is happening genetically without more details.
1) What species are the plants?
2) Are they diploids, tetraploids or something else?
3) For any cross, what did all the other seedlings look like? What do the seedlings look like from other crosses?

The concepts of dominant (and recessive), codominance and incomplete dominance work best when the crosses are between inbred lines and in particular inbred lines that differ only in the same characteristic - that is, they have been made genetically identical except for that one characteristic. When the crosses are between two completely different lines (or strains, etc.) it becomes much more difficult to assign a simple label. Without more information, particularly what do the other seedlings from the same crosses look like, it is not possible to provide an explanation with reasonable confidence.

Thanks for your input.

It is difficult to know what is happening genetically without more details.
1) What species are the plants?
2) Are they diploids, tetraploids or something else?
3) For any cross, what did all the other seedlings look like? What do the seedlings look like from other crosses?

1) What species are the plants?
They are Echinopsis hybrids.

2) Are they diploids, tetraploids or something else?
Assume the parents are diploid Echinopsis hybrids(possibly erroneously?).

3) For any cross, what did all the other seedlings look like? What do the seedlings look like from other crosses?
All are grafted to the same Cereus repandus rootstock, of the few seedlings I grafted there are only four distinctly different:

JHC L1 Choir Mistress shown in the last post,
The Pink seedling shown in the last post,
Oranje Boven,
and another as yet unnamed, with some orange and red.


The first two flowers on the left are older than the one on the right, all are on the same scion.
It appears the color changes as flowers age.

This scion is not as floriferous as the above seedling, scion.

There are still some scions which have not flowered as yet.

Provided the opportunity arises next season, am in Gingin, Western Australia, I will try crosses between all the seedlings and parents.

Unfortunately it will be at least two years before I can reasonably expect to see any flowers resulting from the crosses.

@ausrpned
Do you know the parentage of the female and male plants used in the cross?

admmad said:@ausrpned
Do you know the parentage of the female and male plants used in the cross?

Unfortunately no.

admmad said:The concepts of dominant (and recessive), codominance and incomplete dominance work best when the crosses are between inbred lines and in particular inbred lines that differ only in the same characteristic - that is, they have been made genetically identical except for that one characteristic. When the crosses are between two completely different lines (or strains, etc.) it becomes much more difficult to assign a simple label. Without more information, particularly what do the other seedlings from the same crosses look like, it is not possible to provide an explanation with reasonable confidence.

Have been to the Bozeman site, http://www.bozemanscience.com/..., Unit 4. Just getting my feet wet so to speak.

From http://www.bozemanscience.com/...,
I made the following note.
"Independent assortment genes(traits) operate independently and cannot affect the expression of others and Mendel selected stem length, seed color, seed shape, pod shape, pod color, flower color and flower position are not linked and thus capable of independent assortment."

From other videos I gather this allows "Simple Mendelian" genetics to be applied.

Is that what you are saying is the case with the crosses you have/are dealing with?

In my case would the "This is a seedling from the same cross shown in the "Tree""


in my original post have a good chance of have RW genotype given the nearly uniform Pink coloration?
Cheers

@ausrprned
Simple Mendelian genetics are not usually very simple in the real world. In a lab or in special circumstances they can be relatively simple but in a cultivated/domesticated plant whose breeding population may have been formed from crosses between different species and sometimes between many different species they can be very complex.

One of the first things we would need to look at was how did the different flower colours originate in Echinopsis. As one simple example, if we were working within a single natural species we might find that a white flowered plant appeared after many years of crosses within a uniform population of a different flower colour. So, for example, all plants of a species Echinopsis might have pink coloured flowers and then a single white flowered seedling appeared in a batch of normal pink flowered seedlings. We could reasonably assume that the white flowered individual was a mutant and we could study the inheritance of the white flowers. It would be reasonable to expect their inheritance to be simple - either recessive or dominant and due to the mutation of a single gene.

On the other hand we might find that within that species not all individuals had the same pink flowers. Some individuals might have darker pink flowers and some might have lighter pink flowers. Say we only crossed the lighter pink flowered individuals with each other and only saved the lightest pink flowered seedlings from the crosses. After a few generations of repeatedly using only the lightest pinks as parents and only keeping seedlings that were lighter than their parents we would end up with more or less white flowered plants. It would be reasonable to assume that the inheritance of white would not be simple. It would not be caused by a single mutation in one gene but would likely be caused by natural genetic variation in many genes. Some of those genes would have a larger effect on the white flower colour and other genes would have a smaller effect. There could be 30 or 60 or even more different genes involved in producing the white flower colour.

In any species white (or any other colour) flowers could be caused by either mechanism or by both mechanisms.

In any natural species, if we look at the flower colour of different individuals we usually find that the flower colours are not identical. Natural genetic variation affects most characteristics in most plants and usually many different genes are involved in any given characteristic. In some species there are individuals that differ drastically in flower colour. In those species those different flower colours may be inherited simply. We describe such species as normally genetically polymorphic for flower colour. The different flower colours in those species play some role in the biology of the species.

Typically, flower colour involves at least 30-40 genes. That is what we know about the anthocyanin pigment flower colours and the carotenoid pigment flower colours. Unfortunately Echinopsis have a different flower colour system. Their flower colours are caused by betalain pigments. Much less is known about the genetics of betalain pigments.

In your particular cross the results of just four seedlings indicates that the genetics are not simple. If the flower colour of each parent was caused by just one gene and the parents were "pure breeding" (meaning homozygous) then their seedlings would all have one and the same flower colour. If the white flowered pollen parent was homozygous and the seed parent was heterozygous then their seedlings would have two different flower colours in more or less equal proportions. With four seedlings showing three different flower colours the reasonable conclusion is that two or more different genes are involved. Or that many genes are involved. To try to understand the inheritance of flower colour it is best to start with parents that are homozygous or "true breeding". That means if the seed parent was self-pollinated all its seedlings would have the same flower colour as their parent. The same thing would be true if the pollen parent was homozygous - all its seedlings from self-pollinations would have the same flower colour as their parent.

Is anything known about the inheritance of flower colour in Echinopsis? Do Echinopsis enthusiasts publish photos of the parents and seedlings of their crosses anywhere? Are breeding results published anywhere?

To get even a preliminary understanding of the inheritance of flower colour in Echinopsis, crosses would usually need to produce dozens, if not tens of dozens of flowered seedlings.