The Orchid Garden

Orchid Genetics

Question:

the word to use in your search is "karyotype" as in the sentences: Every species is characterized by a given number of chromosomes that can be recognized by their specific shape. To describe the karyotype of a species it is necessary to determine both number and shape of the chromosomes. another good word to use in a search engine on the subject of orchid ploidy is "Allopolyploidy" which is the type of ploidy that results when plants of different genera or species are crossed.  It is also the thing which screws up a simple mendellian flower color distribution pattern.  Mendel was working with a single species that had mutation on specific chromosomes. Allopolyploidy throws a monkey rench into this problem the size of a small planet. Aneuploidy is another term that comes a lot in this context. The answer to your question asks for a level of understanding on the subject that not many of us, myself included in a big way, can claim.  My interest far exceeds my understanding.  It is a facinating subject though and the archives of this newsgroup on google.com are littered with our attempts to come to grips with it. http://groups.google.com/groups?oi=djq&as_ugroup=rec.gardens.orchids

– Hide quoted text — Show quoted text – That is a bit much to write again.  I suspect if you searched the archives you would find something by me (I know i’ve written about it before), or, even better,  somebody who actually knows something…     In short, ploidy can only be measured by physical counting of chromosomes under a microscope (a pretty simple procedure, given the right stain and a relatively low power microscope).  Anybody who tells you that they can tell by various physical characteristics including leaf thickness or flower size is guessing.  They may be right.  But they could be wrong.  Polyploid plants are often larger, with larger and heavier flowers.  But not always.     You change ploidy by screwing up mitosis.  Nature screws up reductive division during gamete formation at a non zero frequency (pretty frequently, actually), so you can get an occasional naturally occuring polyploid offspring.  In the lab, anything that disrupts the mitotic spindle is a candidate, most labs use colchicine (cheap).  This also happens to be toxic, to both plants and people, so please don’t try it unless you are experienced in good laboratory technique.  If you whack a cell early (during early protocorm development, for example) which happens to survive and develop into a viable plant, you have succeeded.     I bet there is a lot of information that would come out with a quick google search. Rob Would somebody please explain how ploidy of a plant is measured, its impact on the plant and how it is altered??? Thanks Kye.  — The Orchid Index. An Orchid Encyclopaedia Under Progress http://orchidindex.whitehavens.com/index.html ( Soon to be located at www.orchidindex.com ) — Rob’s Rules:           http://www.msu.edu/~halgren   1) There is always room for one more orchid   2) There is always room for two more orchids      2a. See rule 1   3) When one has insufficient credit to purchase      more orchids, obtain more credit

Response:

Would somebody please explain how ploidy of a plant is measured, its impact on the plant and how it is altered??? Thanks Kye.  — The Orchid Index. An Orchid Encyclopaedia Under Progress http://orchidindex.whitehavens.com/index.html ( Soon to be located at www.orchidindex.com )

Response:

That is a bit much to write again.  I suspect if you searched the archives you would find something by me (I know i’ve written about it before), or, even better,  somebody who actually knows something…     In short, ploidy can only be measured by physical counting of chromosomes under a microscope (a pretty simple procedure, given the right stain and a relatively low power microscope).  Anybody who tells you that they can tell by various physical characteristics including leaf thickness or flower size is guessing.  They may be right.  But they could be wrong.  Polyploid plants are often larger, with larger and heavier flowers.  But not always.     You change ploidy by screwing up mitosis.  Nature screws up reductive division during gamete formation at a non zero frequency (pretty frequently, actually), so you can get an occasional naturally occuring polyploid offspring.  In the lab, anything that disrupts the mitotic spindle is a candidate, most labs use colchicine (cheap).  This also happens to be toxic, to both plants and people, so please don’t try it unless you are experienced in good laboratory technique.  If you whack a cell early (during early protocorm development, for example) which happens to survive and develop into a viable plant, you have succeeded.     I bet there is a lot of information that would come out with a quick google search. Rob Would somebody please explain how ploidy of a plant is measured, its impact on the plant and how it is altered??? Thanks Kye.  — The Orchid Index. An Orchid Encyclopaedia Under Progress http://orchidindex.whitehavens.com/index.html ( Soon to be located at www.orchidindex.com )

– Rob’s Rules:           http://www.msu.edu/~halgren   1) There is always room for one more orchid   2) There is always room for two more orchids      2a. See rule 1   3) When one has insufficient credit to purchase      more orchids, obtain more credit

Response:

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