Re: Fwd: HYB:Interploids and Polyploids



On Mon, 29 Sep 1997, Sharon McAllister wrote:

> Walter Moores wrote:
> 
> >  In LA breeding Mertzweiller mentions the above.  Marie Caillet has
> >  just sent me CREOLE RHAPSODY (Mertzweiller '98) and it is described by=
> 
> >  Marie as being an interploid.
> 
> >  Sharon, can you tackle these two terms and simplify them?
> 
> Ploidy is just the number of sets of chromosomes.  =
> 
> It tells us nothing about the number of individual
> chromosomes or their types -- just how many sets =
> 
> there are.
> 
> A diploid has two sets.
> A polyploid has more than two sets.  That includes
> triploids, tetraploids, pentaploids, etc.
> 
> I haven't encountered the term "interploid" before.
> Intuitively, I'd say the product of a cross between
> parents of different ploidy.  It would aptly describe
> the product of such a cross when the true ploidy
> can only be determined by extensive test crosses
> and chromosome counts.
> 
> But that's just an educated guess.  The real
> question is what Marie means by "interploid". =
> 
> 
> Sharon McAllister
> 73372.1745@compuserve.com
>   =
> 
	On page 39 of the SPECIAL PUBLICATION OF THE SOCIETY FOR LOUISIANA

IRISES 1995, Mertzweiller says:

		Availability of tetraploid Louisiana irises may open
		hybridizing opportunities which have not been available in
		the past.  What is considered a new hybrid, I. virginica X
		tetraploid Louisiana (BAYOU ROUGE), was produced by Mr.
		Ken Durio.  This is not only an interploidy hybrid (2n
		X 4n) but also an inter-series hybrid in the Apogon
		(beardless).  I. virginica is diploid, 70-72 chromosomes
		and a member of series Laevigatae.  Louisiana irises
		represent the series Hexagone and are mainly diploid,
		42-44 chromosomes, with the new tetraploids considered to
		have 84-88 chromosomes.  A factor favoring hybridization at the 
		the interploidy level may be related to closer numerical
		similarity in the chromosome numbers.  This may be mere
		speculation and many other factors are likely to be involved.
	

	So, it seems that interploidy relates to inter-species (series) 
crossing.

	Later in the article, mention is made of a cross of I.spuria X
Tet. La giving 104 seeds with seven germinations.

	It remains to be seen whether CREOLE RHAPSODY is a cross between
virginica or spuria.  Marie said it had upright standards, which sounds
exciting.

	Walter Moores
	Enid Lake, MS 7/8
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