Looking for list of plant traits (dominant/recessive)

fran_always(z6 PA)March 25, 2005

Is there a convenient place (book, website) that lists which traits are dominant or recessive for different plants?

I find a bit of info on different websites. Is there a place that has it all together?


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No, not really. There have been published lists for individual species, but I don't know of any comprehensive list covering many species.

If you're looking for info on fruit crops, I might be able to point you in the right direction.

    Bookmark   March 25, 2005 at 10:23PM
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keking(z6 TN)

Dominance is not a stable characteristic of traits, and can be modified by selective breeding. Here are a couple of papers discussing the subject:




    Bookmark   March 29, 2005 at 4:13PM
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I have no doubt that dominance modification can and does occur, but the vast majority of well-characterized Mendelian traits are fairly stable and well-behaved in the context of normal breeding. I still think you tend to be a bit too quick to discount Mendelian genetics entirely, Karl. It may be an over-simplification, but in many, many cases that over-simplification quite adequately explains/predicts the observed behavior, particularly on the level of accuracy needed for breeding. The cytogeneticist may not be satisfied, but all I need to know is roughly what my odds are like on a given cross.

The strawberry populations I scored yesterday are nicely demonstrating 0:1, 1:1, and 3:1 ratios for a couple traits.

    Bookmark   March 29, 2005 at 7:05PM
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keking(z6 TN)


Certainly, mendelizing traits are easier to handle, and seem more "scientific" because of their (apparently) predictable behavior. But there remains the possibility of selective modification of expression, as well as modification of segrating ratios (segregation distortion).

Please note that it was R. A. Fisher -- the statistician who bent over backwards to avoid admitting that Mendel actually falsified his data -- who raised the issue of dominance modification. And it was Correns, one of the co-re-discoverers of Mendelian segregation, who provided some of the first clear examples of segregation distortion.

Mendelism describes a mechanism of reproduction -- meiosis followed by fusion of germ cells. I have no objection to this. But heredity involves biologically useful modifications of the primitive mechanism.

Dioecious plants, for example, need female plants more than males. The segregating mechanism, to the contrary, would provide equal numbers of both sexes. In this case, segregation distortion is beneficial to the species and has been developed by favoring a linkage of the "gene for female" with other factors associated with faster pollen tube growth.

A similar distortion is observed in the double-flowered Stocks. The doubles are sterile, while the single siblings produce offspring segregating for double and single. But more doubles are produced than singles, which is what gardeners prefer. No doubt we could select in the opposite direction.

My point, here, is that the tidy Mendelian ratios exist in the absence of selection for distortion. A study of Arabidopsis thaliana revealed the existence of around 1000 segregation distortion "genes", which should be adequate for anyone who cares to select among them.

Dominance modification is also potentially useful, particularly where a single gene has two (or more) effects -- one desirable, another undesirable. Or, we may be confronted by a tight linkage that we can't break. By selecting for alterations of dominance we may amplify one effect while minimizing another.

I must insist, however, that "well-characterized Mendelian traits" generally have been characterized under artificial conditions. Take the example of the eyeless fruit fly. So long as eyeless specimens are mated to wild types, segregation in the F2 gives about the right proportion of eyeless progeny. Mendel was right! But let the eyeless offspring breed together for a few generations and the eyes will return.

Something similar happens with Lilium martagon album, though less quickly. About 1% of self-seedlings have purple flowers. Do we really want to think of a gene that mutates so frequently?

Then there was DeVries' observation that white flowered varieties of species that normally have colored flowers tend to show at least a trace of the original color. He found that this was selectable, to some degree. So, instead of a neat segregation of white/blue, he was able to develop a (not quite stable) strain of very pale blue. It is easy for a Mendelist to rank these very pale blues as "white" to get the numbers to work out. The same reportedly occurs in strawberries segregating for pink vs white flowers. The palest specimens can be ranked as white or pink as necessary to make the numbers work out.

The sort of plant breeding that interests me most is creative rather than analytical. It takes little skill to find a mutation that segregates with mathematical precision. The art of plant breeding is to identify vague hints of traits, and then to develop them into novel forms or colors. A slight tinge of salmon pink was observed around the beard of an iris, and was developed into the beautiful flamingo pink we have today. Glads with slightly wavy petals were isolated from their siblings; their progeny of later generations have beautifully ruffled petals.

Mendelian inheritance is exceptional. It is most likely to be observed where the normal hereditary diversity of a species has been disrupted, particularly by excessive inbreeding, though change in environment and hybridization are also highly disruptive of normal hereditary transmission and expression.

Menedlian inheritance is easy, but it is not necessarily the best method for breeding. Take a look at the development of the Shirley Poppies, for example.


Here is a link that might be useful: Shirley Poppies

    Bookmark   March 30, 2005 at 3:53PM
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I suspect we could argue this forever, so I won't let myself get to far into it, especially since I don't really disagree with 99% of what you're saying, just your conclusions.

You are absolutely right that these Mendelian traits have been characterized under artificial conditions. It is also the case that Mendelian inheritance is more characteristic of species in which the normal reproductive patterns have been disrupted. However, plant breeding is all about disrupting normal reproduction, and is inherently artificial. I'm trying to generate improved plants, not predict whether such plants should occur on their own.

The question is not whether dominance modification exists, or if a trait can truly be "single gene". The question I am concerned with is, as a breeder, is does this help me to figure out what crosses I should make. If I'm breeding for, say, nectarines, and I cross (peach x nectarine) x nectarine, Mendelian genetics says I'll get roughly 50% peaches, 50% nectarines. And 99 times out of 100, at least, I will. So I know I should have a fair number of nectarines to select among. If I get 100% peaches, or 100% nectarines, or even 100% bananas, for whatever reason one time in a hundred, I can live with that sort of deviation from my expectations, and, if I'm so inclined, THEN I can worry about the effects of other genes, abnormal cytogenetics, (or, in the case of the bananas, divine intervention) etc. Or I can try different parents. Getting Mendelian ratios doesn't have to involve fudging the judgement calls: In several dozen crosses of thornless x thorny blackberries I never had a borderline case, and the ratios worked out perfectly. The strawberry populations we evaluated earlier this week were graded by workers who likely have never even heard of Mendel, let alone had a particular ratio in mind. Not all traits are binary, of course, and any ratio needs to be viewed with a certain skepticism.

From an evolutionary point of view, would the nectarines regain their fuzz eventually if allowed to freely interbreed with each other? Maybe, eventually. But they AREN'T interbreeding freely. As far as I'm concerned, once I make my selection, I don't care what their progeny would be unless I'm using them as parents.

Trying to reduce plant breeding to a matter of sifting through zillions of Mendelian traits is silly, of course. They, do, however, provide a useful guide to maximizing a breeder's resources when selecting for a specific trait. The "art of plant breeding", as you call it, can exist alongside this, I think, as long as one is not too slavishly devoted to Mendel. In fruit crops at least, where most of my experience lies, there are enough "single gene" traits of horticultural significance that behave pretty reliably that the inheritance patterns form a substantial foundation of the breeding programs. Perhaps in ornamentals, where novel traits are more important, one might be less reliant on such things.

    Bookmark   March 30, 2005 at 5:24PM
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keking(z6 TN)


I'm willing to settle for a 99% agreement.

I haven't looked at a high school biology textbook in many years, so maybe things. But when I was in school we spent way too much time with Punnett squares with not a word about segregation distortion or modification of expression -- let alone growing a new trait from hints and whispers. If I seem to take an extreme position, it's just my feeble effort to counterbalance all the useless Mendelian propaganda.

If you are breeding a perenniel that can be propagated ever after, there's no real problem with selective inbreeding. But breeding strains that can reproduce with some stability under varying conditions is quite another matter. Even plants that commonly inbreed (e.g., tomatoes, peas, wheat) can suffer from inbreeding depression, especially if confined to small gardens. In such cases it may be useful to maintain a broader genetic base, which requires shaping the genomic responses so they give a reasonably uniform phenotype despite changing environment and shifting genotypes.

This approach to breeding -- modifying the strain as a whole rather than multiplying an individual -- requires a different set of assumptions and techniques.

No doubt the two approaches can exist side by side. But the neo-Darwinists emphatically denied the existence of any alternative to their "science", and to condemn as frauds any (Burbank, Michurin, et al.) who would not bow before the altar of Mendelism.


    Bookmark   March 30, 2005 at 11:16PM
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I can understand your feelings on "Mendelian propaganda", and I think it's healthy to have somebody advocating on the other side of things, because there is a tendency, even by some people who really should know better, to impose Mendelian genetics on everything.

High school genetics was all Mendel for me...no idea what they do now. Earlier today the undergrad who works in my lab was absolutely stunned that we didn't do electrophoresis in high school biology...so I'm assuming lots has changed. Even as an undergrad it was all Mendel, with a few small exceptions. Once I hit grad school and started dealing with complex messes like Rubus and Fragaria, I had to teach myself a whole new side of things.

I have always worked with clonally propagated crops, so despite my best attempts, that is where my bias is when it comes to breeding. In theory, of course, I've learned all about breeding seed propagated stuff, but I tend not think in those terms unless forced to.

I have the utmost respect for Burbank and Michurin (although Burbank frustrates me, in part because he worked like I often do, by making crosses on a whim, rather than in any systematic, "scientific" fashion that would maximize the benefit from the results (I frustrate myself, too)). My only problem with Michurin is finding translations his works (I can fake my way enough to get the gist of scientific papers in many languages, but Russian is not really one of them).

Anyway, I value your thoughts on these topics, because there IS so little discussion of the non-Mendelian side of things. There is a place for both in plant breeding.

    Bookmark   March 31, 2005 at 4:45PM
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keking(z6 TN)

After posting my comments last night I remembered that I first encountered a discussion of Dominance Modification in my 9th grade science book. But in 10th grade there was nothing about it. Just Mendelism.

BTW, I first encountered Mendelism in 8th grade math class -- an exercise in probability and statistics. Mr. O. had a very dogmatic view of heredity, and no background in biology.

I have Selected Writings (MIchurin) that was published after Michurin's death, and after the neo-Darwinists had taken over in the Soviet Union. Mostly he was reduced to a mere "selectionist". It would have been too difficult to purge him entirely from the history of plant breeding because he had contributed so much. The same with Lysenko.

I agree about the difficulty with the Russian. Even when we can get an English translation there is no guarantee that the translator actually understood the subject at hand. It took me many years and much outside study to figure out exactly what Lysenko et al. were describing. But once I got the ideas firmly in mind, I could see that they were really on to some important practices.

One technique may be called Plasticity Testing. This involves making divisions of a plant and raising each under different conditions. Each specimen will be different, of course, but there should be a pattern to the differences.

For example, one variety may alter the size of its flowers -- larger in preferred conditions, smaller in less favored spots. Another variety will show less variance in flower size, but vary more widely in the number of flowers per cluster, or in the number of branches.

The patterns of plasticity are hereditary! If we wish to breed a new variety with the largest possible flowers, it would be pointless to start with parents that hold their flower sizes relatively constant under varying conditions.

And this, by the way, is what Burbank and other breeders meant when they claimed that acquired characters can be inherited. Strictly speaking, it is the ABILITY to acquire larger flowers in preferred condtions that is inherited directly. And once we know how to provoke plant (or strain of plants) to produce the largest flowers, we can select AGAINST any "genes" that interfere.

In other words, it is easiest to select among "genes" that affect flower size when the plant is making large flowers. If we tried selecting under conditions that favor small flowers, we'd have a harder time separating inherent differences from environmental variations.

Another very useful technique that Lysenko discussed is the use of pollen mixtures. This, of course, is highly "unscientific" because we lose information about the precise lineage. But the old mendelists tended to forget that pollen tubes are multicellular organisms with properties of their own. Through the use of pollen mixtures we place the male gametophytes in direct competition -- survival of the fastest, in this case. Too often experiments in selective inbreeding have led to sterility -- because the experimenters did not give pollen tubes and egg sacs (female gametophytes) their own opportunities to compete.

Faster pollen tube growth has been shown to be correlated with increased vigor of the resulting sporophytes, so the Michurinists were right again.
Quesada, et al. Effects of pollen selection on progeny vigor in a Cucurbita pepo x C. texana hybrid. TAG Theoretical and Applied Genetics 92(7): 885-890 (1996)

Iarovization is another broad concept that I'm still learning about. It is NOT merely vernalization, though it includes that as well.

As an agricultural practice, iarovization protocols encourage the activation of digestive enzymes (amylases, phytases, proteases) in the seed, bulb, tuber ... any dormant bud, while keeping the embryo or meristem dormant. Thus, when germination or sprouting is allowed to begin, the new growth has a readily available supply of water soluble nutrients.

Iarovized seed can be dried and stored.

Now, when iarovized seed is planted at the same time as untreated seed, both batches must imbibe water, presumably at about the same rate. In both batches the embryos are awakened and begin growing. The difference is that seedlings from untreated seed can grow only as fast as the digestive enzymes allow. Embryos from iarovized seed can "hit the gound running", and grow about as fast as their cells can divide.

This agricultural practice should not be confused with iarovization testing, which is a straight-forward exercise in selective breeding. A. A. Avakian developed Spring forms of all the important Winter wheat varieties with this method.

Simply stated, a quantity of seed from Winter variety is divided into several lots. 40 days before planting the first batch is moistened and placed into cold storage (a few degrees above freezing). Five days later a second goes into storage. And so on, about every 5 days, until the last batch goes in 5 days before planting.

On planting day, each batch is planted in a separate plot. The plants from the the 40 day batch probably give full germination and flowering. We don't need them. The 5 day batch may not germinate at all. That batch isn't needed, either. The only plot that is of interest is the one that shows partial germination with just a few plants that manage to flower and produce seed. These plants are the foundation of a new strain, similar in most regards to the original, with reduced a chilling requirement.

The process can be repeated a time or two for further improvement.
Converting Winter Wheat

This method is similar in principle to selecting for flower color. The obvious difference is that variation in chilling requirement cannot be seen without the sort of test Avakian used.

Graft hybridization is another technique that gave the Mendelists fits. They were particularly metaphysical at this point. They saw no reason why grafting SHOULD modify the heredity of a plant, therefore grafting could not modify the heredity of a plant. I'm thinking of the Vatican astronomers who refused to look through Galileo's telescope because there was no reason the sun should have spots.

Modern research has shown very definitely that grafting can alter the heredity of plants, and that some of the changes are passed along to seedlings.

It is amusing to read Lysenko's patient discussion of graft hybridization. He explained that it is very easy to demonstrate with tomatoes, and that sceptics should try it for themselves. But the neo-Darwinists would have none of it. They countered that they were too busy with "real" science to waste their time on unscientific nonsense. They didn't mind raising hundreds of thousands of fruit flies that never fed anyone, but could not spare a few minutes to graft a tomato to a black nightshade.

As for Burbank's "whims", I prefer to think of them as "hunches". Need I mention that I do it too?


Here is a link that might be useful: Vegetative Hybrids

    Bookmark   March 31, 2005 at 6:12PM
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membertom(zone 6)

I just want to take this opportunity to thank you for your discussion and especially for your website. I've been actively hybridizing (roses, irises, daylilies, wheat, strawberries, lettuce, maize/tripsacum, columbines, viola....you get the picture) since my first cross in 1987, and thanks to the information on your website, I'm going to also try some vegetative hybridization this year. I've got some peppers I've overwintered indoors, that I plan to try seedling tomato grafts on. I also plan to repeat the Russian lady's graft of tomato on Solanum dulcamara.
I very much enjoyed the Burbank blue poppy selection article. It's reassuring information. My own "hunches" are seeming even more viable now.
I'll include a link to my old website below, in case you want to see some of my past hybridizing. It's mostly of rose species hybrids, with a few pictures of viola, iris, wheat and tomato hybrids thrown in.
Thanks again, Tom

Here is a link that might be useful: Pictures of some of my older stuff

    Bookmark   April 7, 2005 at 9:10AM
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keking(z6 TN)


Great! I've spent a lot of years quietly collecting odd bits of information on heredity and hybridization for my own use and education. I am delighted when other people can make use of the info.

And speaking of rose species hybrids, did you notice the article by Skinner about his use of Rosa virginiana alba?

I added a few other similar items -- "albino" plants (white strawberries, white Lilium martagon album). This is not an overwhelming body of evidence, but it does suggest to me that difficult hybrids might be a bit easier if the seed parent is "defective". In these few cases the absence of pigment seems to have made a difference. In other cases, placing the seed parent under environmental stress may improve the odds of getting successful crosses. Ivan Michurin seems to have pioneered the technique, but more recently Christy Hensler hit on the same method independently. If you haven't seen her hybrids of Japanese and Siberian irises, you're missing a real treat. She even crossed a JapxSib with Iris pseudacorus to produce her lovely 'Shape Shifter'. I'm attaching a link to her web page below.

The graft hybrids -- boy have I had a hard time persuading people that these are not chimeras. It's easy to dismiss what some "foreigner" claimed to have done in the late 19th century, but when modern scientists associated with respectable institutions are getting the same results, even stubborn people start to pay attention.

The "trick", according to Michurin, was to use an old variety as stock and a young specimen as scion. It also may help to pull leaves off the scion, though the newer reports don't mention this -- that I've noticed.

The opposite of graft hybridization is "mentoring". Michurin would graft a branch of a mature variety onto a young specimen that wasn't quite measuring up. Sometimes the flaws could be corrected through the influence of the mentor.

I think someday there will be a general theory of graft hybridization/mentoring. My guess is that it will involve cellular memory that resides in the membranes. Not all information pertaining to heredity is locked up in the chromosomes! Young plants eventually figure out for themselves how to regulate their heredity in the prevailing environment, but a grafted branch from an adult can "educate" the young one. Or that's how it looks.

Heredity is not as mechanical as textbooks would have us believe. Naudin reported on this fact in the 19th century. We often can see it in young hybrids. For instance, hybrids of blackberries with raspberries may be undecided about just how the fruit will be attached. Some fruit will slip free from the core (like raspberries) while others on the same plant will remain firmly attached (like blackberries). Still other fruit will be variably attached. This might be a place where mentoring could persuade the young hybrid to go one way or the other.

I just took a quick look at your web page. Very nice! I'll add a link to my own page, and mention yours to some of my rosarian friends.

Did you read Fagerlind on chromosome doubled roses? Among other things he had a chimerical Rugosa -- part diploid and part tetraploid.

And did you know that chromosome doubled plants can sometimes revert? Spontaneous somatic meiosis. Though the new tissues are diploid they will not be similar to the original diploid thanks to segregation. And you may be able to induce somatic meiosis by feeding the tissue free (unpolymerized) DNA or caffeine. That might be something to try on your tetraploid Rugosa x Xanthina.

Rosa rugosa doesn't do well with yellow. 'Agnes' is a beautiful rose but does not come close to the brilliant yellow of R. foetida. The problem is that carotene can be retained as color or burned off as perfume. I'll bet your hybrid is more fragrant than the Rugosa parent. We run into the same problem when breeding cluster-flowered roses. So far as I've seen, you can't get a small flowered cluster AND deep yellow coloring -- except in R. banksiae lutea. The yellow Noisettes, for example, the deepest non-fading yellows always have one or a few flowers per cluster. The many flowered types are usually very fragrant but whatever yellow color they have fades quickly.


Here is a link that might be useful: The Rock Garden

    Bookmark   April 9, 2005 at 7:40AM
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membertom(zone 6)

Yes, I have seen the Skinner virginiana alba article. And I think every other rose article you've got on your website; I've been visiting for years now. I've been using some of the native tetraploid roses (carolina, virginiana and arkansana) in my hybridizing recently. My favorite so far is 'Fragrant Cloud' X carolina. (And it's fertile too!) I'll include a link below. I'll have to keep the defective and/or pigment-lacking idea in mind when choosing seed parents for my wide-cross attempts.
I've been following Christy Hensler's website for a while also. She's been treated with quite a bit of skepticism by some members of the iris community, but I think they've been too quick to dismiss her work.
In light of the information about vegetative hybridization, I've been reorganizing in my head all of the "traditional genetic" thought, that I've been so used to. I can hardly wait to try out some stuff.
Thanks for the compliment on my website. It's only a small sampling of what I've been working on, and hasn't been updated in years. But, it at least gives a little idea of what my interests are.
And unfortunately, I've lost the rugosa X xanthina (potentially doubled/tetraploid) branch. But I still have the that diploid hybrid (and many others) and I've got a potentially converted branch on a different sterile rugosa hybrid.
I don't think that the hybrid (rugosa X xanthina) is more fragrant than rugosa, but it is a different kind of fragrance (like scotch rose). There must be different pathways for different fragrance compounds. Some of them are probably not derived from carotenoids. Consider Hazeldean and foetida, two of the most saturated yellow roses, and both very fragrant (although maybe not typical rose fragrance).
I'd like to get some direct hybrids between pimpinellifoliae and synstylae roses to see how the yellow (carotenoids) vs. fragrance thing works out. I had thought of the cluster vs. yellow issue before.
Thanks again for all the information.

Here is a link that might be useful: 'Fragrant Cloud' X carolina

    Bookmark   April 11, 2005 at 9:40AM
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keking(z6 TN)


I stumbled on an article discussing some Polyanthas derived from Polyantha x Foetida crosses and similar. I had already grown one of these, 'Mevrouw Nathalie Nypels', which is very fragrant. This got me thinking of other information I had -- such as Michurin's cross of the Damask rose 'Kazanlik' and 'Persian Yellow'. It was a difficult cross -- the seedlings died young -- but he rescued some by grafting them to seedling Canina. He then crossed one of them with 'Clothilde Soupert'. A selected seedling had the plant of Foetida, fragrance of Kazanlik but with clusters of flowers similar to Clothilde. And by test this variety produced more attar (fragrant essence) than Kazanlik. Then I found an early 19th century description of a Lutea (Foetida) with sweet scented pink flowers in clusters -- very much like Michurin's 'Slava Sveta'.

It is odd that a Polyantha (diploid) pollinated by a tetraploid Foetida should sometimes give diploid hybrids, but there are multiple instances.

Yes, there are different kinds of perfume in roses. The carotenoid scents are usually the most powerful -- when first isolated, these rose ketones were described as "trace" components, but proved to contribute more to the scent than other, more concentrated substances like citronellol.

Terpenes are also present. China roses produce mostly terpenoid scent (geraniol). Rose oxide -- which distinguishes "old rose" from almost every other fragrance -- is an ester related to terpenes, but I don't know the chemical pathway. I'm just glad we have it.

I don't know the chemical basis of the "incense" scent of the yellow roses, which is reportedly stronger in the wood than in the flowers.

The biochemistry of carotenoid perfume is amazingly complicated, and can yield a weirdly diverse range of scents. From the distinctly floral damascenone (found in roses), ionone (violet) and irone (iris) to the smell of straw found in saffron. Here's a link to get you started.

By the way, I moved my web page to www.bulbnrose.com so I have more room to play than I did on Geocities. Next time you update your page (with more pictures, I hope) you might make the correction.


Here is a link that might be useful: Carotenoid perfumes

    Bookmark   April 11, 2005 at 5:40PM
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pinetree30(Sierra Westside)

Keking writes that Mendelism and Michurinism have nothing to do with politics. Such a cynical statement can only be left unchallenged by those who are unaware of the pre-emption of Michurinism for ideological reasons in the Soviet Union, as a prop for Communist ideology; and the viciousness of attacks on anyone or anything that could be labeled as Mendelist or Morganist. One need only read the 1949 Proceedings of the Lenin Academy of Agricultural Sciences in which Lysenko drops the axe on those who oppose his views, with the full approval of Comrade Stalin.
And for Keking to speak of the "taking over" of Russian genetics by the Mendelists, without noting how few survived Lysenko's purges with their lives or laboratories, is to whitewash the twentieth century version of the Inquisition.Those survivors are now helping to bring Russia into a new century. Keking calls into question his posture of just being a defender of science, and seems to be a defender of so much more.

    Bookmark   October 20, 2005 at 5:03PM
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Pierre_R(z9 Riviera)

Even if oversimplified Mendel findings are essential for genetics understanding particularly for the non mendelian ones.

Main objection to Michurine is that even with considerable investments his views led to little achievements beyond poetic litterature. So much that he is no longer supported in his country.

That traits are dominant or recessive is largely environment dependent.
Genetic, cytoplasmic and ologic/climatic environment.

    Bookmark   October 22, 2005 at 12:29PM
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Classifying an allele (alternative form) of a gene (locus) as dominant or recessive or partially dominant, or overdominant or codominant has as much to do with how we observe and measure a trait as it does with how alleles act.

As a hypothetical example: I cross a true-breeding (homozygous) scarlet red-flowered plant with a true-breeding yellow-flowered plant. I observe (by naked eye) that all the offspring (F1) are not yellow (they are reddish). I cross the F1 offspring with each other at random and notice that some of their offspring (F2) are yellow and the rest are reddish. I classify the F2 into two groups, yellow and not yellow. The not yellows are reddish so I label them as red. I count the two groups and find that there are three red to every one yellow. I conclude that one gene is involved and that red is dominant to yellow on the basis of no yellows in the F1 and a 3:1 ratio of red:yellow in the F2.

A second observer examines both the F1 and the F2 and agrees with the lack of yellows in the F1 but in the F2 finds that the reddish shades vary. The red F2 offspring are not all scarlet red. The second observer disagrees with the conclusion that only one gene is involved and that red is fully dominant to yellow. On closer examination of the F1 the observer declares that since the F1 are not scarlet red that red is only partially dominant to yellow.

A third observer might measure the concentrations of pigments and find that although there was one major gene there were many other genes with small effects actually determining the amounts of both the yellow pigment and the red pigment in each F2 individual.

For the purposes of predicting the phenotypes of the F1 and F2 all the observers are correct as long as they define completely the traits that they are observing and how they measure them. (And they measure those traits in all individuals in all generations consistenly the same way).

As far as the genetic situation, only the observer who measures the amount of messenger RNA (mRNA) for each allele, the amount of protein present coded by each mRNA, the activities of each protein (enzyme?), the amounts of each pigment in the F1 and F2, etc. will understand the relationship between the genotypes and the phenotypes.

    Bookmark   October 22, 2005 at 5:56PM
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Back to the original question only a little more specific. In particular, tomato breeding. I am new to gardening, and next year I intend to cross breed some heirloom tomatoes. Is there a web site that someone can reccomend that will help to learn the dominate/recessive traits and how to predict results using a punnent square? For example, the proper way to describe genetically a potato leaf purple tomato crossed with a regular leaf yellow/orange tomato, and the ratios of predicted results. Also, how many plants you might have to grow to get all possible genetic combinations. Thanks, Paul

    Bookmark   December 23, 2005 at 7:00PM
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Try the tomato genetics resource centre. There are lists of genes and their designations and descriptions with other information as well.

There are also some Tomato Genetics Bulletins (older) on the web at The Tomato Genetics Cooperative at http://tgc.ifas.ufl.edu/

Here is a link that might be useful: C. M. Rick Tomato Genetics Resource Centre

    Bookmark   December 25, 2005 at 11:31AM
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saltcedar(Sunset zn 30/usda 8b)

Now that Bulbnrose.com is gone is it's information available online?

    Bookmark   May 2, 2008 at 5:28PM
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While it is a delight to read Burbank's books and catch the 'feel' of his passion, he did hold to some very unorthodox notions about 'aquired characteristics'. He also had the backing of Stark's Brother's Nursery and a large fund to draw upon, so that he was able to plant thousands of specimens from his crosses. Simply having such a large 'test' population to draw from enabled him to select some superior seedlings. As to his theories and beliefs as to why he did achieve the results, well, that ventures into the theoretical. And can easily be compared to the logical fallacy. Post Hoc-- concluding that because one event occured before another, the first was the cause of the second.

    Bookmark   May 11, 2008 at 3:49PM
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If a plant had one char. that you really liked, there is one way to promote its being passed to offspring. Self the parent plant, and save the seeds.
Plant out the seeds and select for the one that has the most pronounced expression of the char. you're seeking.
If it is a color, you'd plant out the seedlings of, say a Red Orange Calendula flower that had been grown in isolation to avoid cross pollenation.
When you plant out these seeds, you will see variability in color.
From that population destroy all but the dark Red Orange Blooms and then from this population, save the seed.
These seedlings will be more homozygous for that color than the original parent.
It may take more than one generation to have plants that breed 'true', and it is common to see an inbreeding depression in vigor, but you can then outcross to superior Calendulas that have another desired char., 'Double flowers or longer stems or more compact.
With Grapes it takes a lot longer than with flowers.

    Bookmark   December 9, 2008 at 4:48PM
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mistercross(z6b Ozarks)


If you're looking for old web pages like bulbnrose.com then try an internet archive like wayback machine.

These are imperfect. Imagine trying to backup a site that changed daily, like Gardenweb. Or the site may change much over the years. And try to take a snapshot of every linked site. How often do you have to backup the entire internet?

But, broken links and all, at least part of the information you want is available. Go dig.

Here is a link that might be useful: Bulbnrose at archive dot org

    Bookmark   March 15, 2009 at 6:34PM
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membertom(zone 6)

That's cool mistercross, I didn't even know sites like that (archiving old websites) were around! That's good to know.

As for Karl King, he does still have a current website. It's just moved to a ".org" URL. I'll put the link below:

Here is a link that might be useful: Karl King's CyberGarden

    Bookmark   March 18, 2009 at 9:11AM
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