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Present were 23:
mplewinska (Dr. Magda Plewinska - Miami FL)
mlp2 (Mary Lou)
55SS (James - Fresno)
TJCasler (Eugene OR)
Josh319 (Iowa)
marylois (northwest LA)
JCY8S (John - Arcadia CA
marilyninOttawa
sparkysteve (Boca Raton FL)
graphicgreg (South FL)
Ellen,Smithtown,NewYork
Jane5536 (Huntington L.I. N.Y.)
GUEST fancyfarmer (517)
Btague (northern CA)
Evlyn (northwest LA)
lisav-bigred (Lisa in Fort Myers, FL)
paulav (Boca Raton FL)
gaillevy (Boca Raton FL)
Ruckster1 (Sharon - east TX)
Peterlin (Dallas TX)
AORCHID (Art - SC)
uncleearl (Vacaville CA)
knudy (Kip)
mplewinska (Magda from Miami)
Hi, everyone. I'm here. Ready for genetics?
gaillevy ( Boca Raton, Fl)
Good evening Magda, we're all ears.
mplewinska (Magda from Miami)
Questions? Does everyone remember what we did last time?
graphicgreg (bonnie begone)
We're ready to rock n' roll Magda...fire away.
mplewinska (Magda from Miami)
OK, guys, who knows what a gene is?
JCY8S (John in Arcadia, CA)
Nature's building block or planning unit?
55SS (James in Fresno)
Genes make up DNA?
mplewinska (Magda from Miami)
Well, that was actually a trick question, because a gene is getting to be pretty hard to define.
JCY8S (John in Arcadia, CA)
A gene is something that contains the instructions for replication isn't it?
mplewinska (Magda from Miami)
A gene is generally though of as a fragment of DNA that contains the information to make a single polypeptide chain.
graphicgreg (danielle begone)
Magda, how does a gene relate to a chromosome ?
[a chromosome contains a lot of genes - thousands of them -mp]
mplewinska (Magda from Miami)
Polypeptide is a simple protein, by the way. The trouble with deciding what a gene is, is that the regulation of that single polypeptide can involve a lot of other pieces of DNA, like promoters and enhancers, that regulate the gene. So people are still fighting whether the regulatory parts are part of the gene or are separate. Is that pretty clear?
Jane5536 (Huntington L.I. N.Y.)
Whoo--this sounds really deeeep.
mplewinska (Magda from Miami)
About replication. Usually a gene does not contain instructions for its own replication. Replication takes a number of genes. So the genome (all the genes in a cell) does contain the instruction for its own replication.
graphicgreg (danielle begone)
We're with you so far Magda...kinda like the taxonomists fighting over whether variegatum is an Oncidium or a Tolumnia.
mplewinska (Magda from Miami)
Greg, now you're talking. WRT genes and hurricanes.
JCY8S (John in Arcadia, CA)
So a 'cell' replicates, not the gene as such.
[Well, the genes are replicated during cell division but they don't do the replicating themselves. All the work is done by proteins. The genes contain the information about how to make the proteins. So what came first, the chicken or the egg? Well, the initial machinery for DNA replication and making any extra needed enzymes (proteins) is present in the oocyte (egg cell). The new embryo needs that stuff to get started. After a little while, it will make its own. The most popular theory as to how it all started all
those millions of years ago is "with RNA," but that's another question altogether.]
mplewinska (Magda from Miami)
I think of DNA of a cell as an encyclopedic cookbook. It contains all the instructions necessary to make whatever it is you need but you can't eat it. You need other ingredients to use the information.
JCY8S (John in Arcadia, CA)
Interesting analogy.
marylois (Topic: Genetics 201)
There's a nice little writeup in the VBOS Orchid Times of Roy Tokunaga on Genome Hybridizing of Miniature and Compact Cattleyas. 'The term genome breeding was used by Dr Kamemoto to describe hybrids that are composed of two or more species with their entire genome present.'
mplewinska (Magda from Miami)
I didn't see the Roy Tokunaga article. What does it say? Putting the entire genomes together would get rid of the problem with different chromosome numbers in the parents. So theoretically you should always get fertile 'offspring'
marylois (Topic: Genetics 201)
Briefly, Magda - goes with what you were saying...in order to have these complete genomes present in one plant, a number of tetraploid species and primary hybrids were created using colchicine...then they made a series of test crosses to understand behavior of the tetraploids...in slides, he followed ten years of Sc. Beaufort breeding. Shall send it along and perhaps you would like to include it in this evening's transcript - graphic illustration of the theory.
mplewinska (Magda from Miami)
Does everyone understand why different chromosome number in the parents would result in infertile offspring?
JCY8S (John in Arcadia, CA)
In that case Magda, couldn't you cross ANY genus with another? Not all genes can 'hook' up with its like. I think.
mplewinska (Magda from Miami)
JCY, theoretically, yes. But I suspect that if the parents are different enough, you would get a very confused plant that would not grow well.
JCY8S (John in Arcadia, CA)
Confused would be an understatement, I think.
mplewinska (Magda from Miami)
JCY, about genes 'hooking up with their like' is right! You have to do that to get viable gametes (egg and sperm).
JCY8S (John in Arcadia, CA)
Magda - that is what I thought as viability would decrease if all genes weren't available to be used.
mplewinska (Magda from Miami)
It's not that the genes are not available. The problem is that at the stage when the chromosomes split up, one of each pair going to a different daughter cell. Before this can happen, they have to be paired with their analogues - a chromosome similar enough so it will stick well. If they don't have an analogue to pair with, they won't be able to assort correctly and the resulting gametes will have too few or too many of some chromosomes. When the parents are different enough, their chromosomes are also different,
in composition as well as number, and in the offspring, they just can't find another chromosome to stick to. So that's why the offspring may be infertile.
One of the weird things I learned about plants is that sometimes extra copies of a gene (anything more than the normal 2) are inactivated. This was discovered when transgenic plants didn't do what was expected of them. I don't think the way this happens is really understood, but I wonder if something like that might not happen in these genomic hybrids.
JCY8S (John in Arcadia, CA)
Magda - could you give us your email address? I have a genetic question that really is very specific and it really doesn't fit in with this discussion.
mplewinska (Magda from Miami)
The offspring would be infertile because it cannot form gametes with all the chromosomes they need. My email is mplewinska@mindspring.com
mplewinska (Magda from Miami)
Lois, what were the species in the Tokunaga article? All Cattleya alliance?
marylois (Topic: Genetics 201)
Magda: From the article - 'e.g., the nearly infertile diploid hybrid Den. Jaquelyn Thomas is composed of one genome from Den. phalaenopsis and one genome from Den. gouldii. When the chromosomes of this hybrid are doubled, fertility is restored. It then produces uniform 2N gametes composed of one genome of Den. phalaenopsis and one genome of Den. gouldii. These special pure breeding tetraploids composed of two species are called amphidiploids. These tetraploids can be crossed to other tetraploids to create uniform populations that are all tetraploids.'
The article is about miniature and compact cattleyas, but the breeding program is based on applying tenets of Dr. Kamemoto's work with dendrobiums.
mplewinska (Magda from Miami)
Lois, so both are using species that are related, not two things that are totally different.
marylois (Topic: Genetics 201)
Absolutely -- to my knowledge, they still have to stay within family breeding groups. In the work with Beaufort they are, of course, using sophronitis and cattleya. I guess, technically, it would work with more species present in the hybrid... time will tell.
marilyninOttawa
One question I have, Magda, is concerning species breeding behaviour. I have a small population of Epidendrum species raised in flask from a single jungle-collected seed population. The plants are individuals. There are subtle differences between individuals. I cannot get them to self or to sib cross to get more seed. However, the plants are all fertile seed and pollen parents when crossed with a variety of other Epidendrum species. What do suggest is the problem? Is it a genetic problem?
JCY8S (John in Arcadia, CA)
Marilyn - could the original plant have not been a complete one in that it had more or less of some gene(s)?
mplewinska (Magda from Miami)
Marilyn, I would imagine it's a genetic problem. Maybe your plants have some recessive genes that is lethal to the offspring. Are you getting any pods at all?
marylois (Topic: Genetics 201)
Maybe treating them with colchicine and doubling their chromosomes would work on them too, Marilyn.
JCY8S (John in Arcadia, CA)
Lois - that is what I was just thinking (great minds? LOL)
mplewinska (Magda from Miami)
Marilyn), are your plants from a single pod?
55SS (James in Fresno)
Or if you are willing to pay, have a lab to embryo rescue.
marilyninOttawa
I have never had any fruits form when sibbing or selfing but absolutely no problem using the plants as seed or pollen parents. Would this suggest that the other parent is somehow diluting an allele that is recessive and lethal when present in maternal and paternal genes?
JCY8S (John in Arcadia, CA)
Marilyn - can you get any pollen from a plant that is not in your population? If so you might try that.
marylois (Topic: Genetics 201)
Roy: 'There are several benefits in using amphidiploides to keep the entire genome of the original species intact into the next generation: 1) restoration of fertility, 2) hybrid vigor is maintained with two or more complete genomes, 2) colors are more predictable and enhanced, 4) fragrance is maintained into the hybrids, 5) flower characteristics, plant structure, blooming season, and uniformity of the progeny are more predictable, 6) remakes are identical to the original cross, 7) one amphidiploid can anchor a large number of
crosses.'
marilyninOttawa
I enquired of the collector who is very knowledgeable. The seedlings came from a single capsule.
JCY8S (John in Arcadia, CA)
Marilyn - what is the plant? Maybe someone has heard of another one.
marilyninOttawa
There are no embryos to rescue, James. From what I have observed, pollen does not germinate on the stigmas. This suggests that the lethal factor is likely being expressed in that region. It is an interesting problem, and no, I do not have access to another population.
mplewinska (Magda from Miami)
Marilyn, yes, I a recessive lethal could explain this. But you would still expect only 1/4th of the offspring to be affected. There is another problem with related individuals in humans, but I don't know how this happens in plants. In humans, you need an inflammatory reaction for the embryo to implant, so if the parents are too alike immunologically, they may have a problem with fertility. Maybe the plants recognize the pollen/stigma from relatives ???? This is totally wild speculation.
marilyninOttawa
Epidendrum janeirense
55SS (James in Fresno)
There are a few ways to overcome pollen incompatibility that may work, but are probably not worth the trouble.
mplewinska (Magda from Miami)
Marilyn. I guess like you said, tetraploids might work. But then they wouldn't be exactly the same plant.
marilyninOttawa
One can soak the pollen in enzyme solution designed to remove proteins from contact lenses. I might try it. Good idea, James.
55SS (James in Fresno)
I was thinking more like something I read about in one of my propagation books where they take a piece of the ovary and get the pollen directly to the ovules and culture the piece of ovary in a flask or something.
marilyninOttawa
I really do not want to play around with colchicine. I am more interested in the possible impact a situation like the one I describe has on a wild population. Obviously, for these seedlings to have been created, some combination of seed and pollen parent must have worked.
marylois (Topic: Genetics 201)
Nor I. Colchicine is for experts... just thought there might be someone around to give it a try... wouldn't hurt to have more of those epis around! *S*
uncleearl (Earl from Vacaville, CA)
Aloha - Sorry I'm late. Looked forward to this one!
mplewinska (Magda from Miami)
Hi, uncleearl. lois, I think that part of Marilyn's objection to colchicine is that it's not what happens in nature (as a rule). Am I right?
marylois (Topic: Genetics 201)
uncleearl - perhaps foremost is the dangers of messing with colchicine...re: not being same plant... neither are the offspring of 'selective breeding'. Oh, how philosophical we become. *S*
marilyninOttawa
I am not objecting to the horticultural use of colchicine Magda. I am simply curious about natural breeding systems.
mplewinska (Magda from Miami)
Marilyn, that's how I thought you felt about colchicine.
marylois (Topic: Genetics 201)
Well, lots of tetraploid breeding is in the works, with lots more to come! ... whatever we think of it. Roy says his biggest problem has been a shortage of miniature tetraploids - BUT he 'looks forward to the future because I have just found or created several new amphidiploids and tetraploid species.' On the plus side, clones will really be clones.
mplewinska (Magda from Miami)
About your plants, Marilyn, maybe there is an environmental factor we don't know about. Maybe they need some substance that isn't around or something in the artificial environment is interfering with pollination. Or they need an insect to do something specific.
marilyninOttawa
What puzzles me, Magda, is that I do nothing special to get hybrids with these plants. I have 'about to bloom' seedlings of E. janeirense with E. pseudepidendrum and with E. ilense (both ways) and with an Epicattleya.
marylois (Topic: Genetics 201)
What interesting crosses!
mplewinska (Magda from Miami)
Marilyn, is this species closely related to a common one? Then maybe introgression would be a way to go.
mplewinska (Magda from Miami)
Of course, introgression would take a lot of generations to return to the original species.
marilyninOttawa
I suspect that this epi is related to Epi. peperomia. This miniature species has large clusters of flowers. It looks as if it will influence the stature of the hybrids and I am always interested in keeping height down to what comfortably fits under lights! The jury is out on the flower appearance, especially color.
mplewinska (Magda from Miami)
Have you tried crossing your plants with Epi. peperomia?
marylois (Topic: Genetics 201)
Oh, my - even more interesting...when you flower the cross using ilense, PLEASE share photo - for that matter, the pseudepidendrum offspring should be most interesting as well.
marilyninOttawa
No, Magda, I have not tried with E. peperomia
55SS (James in Fresno)
Is peperomia similar to porpax?
mplewinska (Magda from Miami)
Marilyn. Maybe that's the way to go. If you are interested in introgression. But it would not answer the question of why these guys won't cross among each other. It's an interesting dilemma.
marilyninOttawa
Magda, this is a dilemma often faced by conservationists with a limited population to deal with.
marilyninOttawa
Must fly. Thank you, Magda. Good night.
knudy
I am interested in attempting Cyp. x Phrag. Have you any helpful suggestions?
mplewinska (Magda from Miami)
No helpful suggestions. You just have to try it. Either it works or it doesn't.
AORCHID
Nice discussion, but I almost flunked genetics in college and that was 25 years ago. Had enough trouble with fruit flies.
Evlyn
Nite. Thanks, Magda
mplewinska (Magda from Miami)
Fruit flies are hard - you got to catch them. Plants are much easier. They seem to tolerate a lot more chromosome weirdness.
AORCHID
You don't have to wait as long for fruit flies though.
mplewinska (Magda from Miami)
No, I find that out on a regular basis when I don't empty out my 'composting garbage' often enough :)
marylois (Topic: Genetics 201)
Gee, fear I stepped on your genome, Magda...did I sidetrack other data you wished to present?
mplewinska (Magda from Miami)
Don't worry about it, Lois. I pretty much go with what people want to talk about. This was interesting.
marylois (Topic: Genetics 201)
Well - shall we schedule 202, and I'll leave Roy at home? *G*
BTague (Barbara,No. Calif.)
I'm back, it was a wonderful talk, just more then I need to know for this hobbyist.
mplewinska (Magda from Miami)
Oh! Roy! Sure, we can schedule another. But first I got to get through Danielle. It wouldn't be so bad if we weren't planning to go away for the weekend. That way we have to make the decision to go or stay by tomorrow night.
marylois (Topic: Genetics 201)
Hi, Barb - but kinda nice to know where new hybrids come from.
mplewinska (Magda from Miami)
BTague, well why didn't you ask the questions you want to have answered?
gaillevy ( Boca Raton, Fl)
Magda, I'm here haven't much to say, I'm speechless.
mplewinska (Magda from Miami)
Gail, you speechless???? Genetics IS a powerful thing :)
marylois (Topic: Genetics 201)
Great, Magda...thanks for all your effort this evening. Good to think a little harder once in a while. *S*
BTague (Barbara,No. Calif.)
Magda, you did a good job, just that I'm speechless also.
mplewinska (Magda from Miami)
Lois, you're welcome. Barbara, think of some questions for next time. OK? :)
BTague (Barbara,No. Calif.)
Madga, don't wait for me. I don't even like to grow seedlings. I hope you can understand.
mplewinska (Magda from Miami)
I think for next time, everyone should send me or Lois their questions ahead of time and I'll try to answer them. I won't tell anyone whose question it was, so you don't have to feel stupid. And it's really true: There are NO stupid questions.
marylois (Topic: Genetics 201)
Sounds good, Magda...give me something to send them welcoming questions to you in advance, okay?
knudy
I'd like to find a list of chromosome #'s to match possible pairs. Help?
mplewinska (Magda from Miami)
Knudy. There are lists of chromosome numbers scattered over many books. Try Arditti and Withner. But don't forget, the number doesn't tell the whole story.
mplewinska (Magda from Miami)
I think I got to go, too. I'm getting veeeeery sleepy tgl;ksfjoif. Sorry, that was my head hitting the keyboard :)
marylois (Topic: Genetics 201)
Nite, Magda - thanks once more. Think it's the witching hour for all. Nite, all - last one turn out the lights.
gaillevy ( Boca Raton, Fl)
I'll turn off the lights!
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