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  Aroid breeding problems
From: Brian Williams <pugturd at alltel.net> on 2009.01.04 at 14:35:51(18859)
I have been working on breeding aroids for many years now. I have found
a few species that show some very interesting traits that I am looking
to work with. These aroids are self fertile but if I add pollen from a
different similar species it never takes. I remember having similar
problems with Amorphophallus bulbifer. What is the cause of this and why
is the pollen unable to take? It really does not make much sense to me
sense the plant is fertile and able to receive it's own pollen. I would
think that a similar species would easily cross with it. Is their any
way around this barricade?
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From: agrsuw at ku.ac.th on 2009.01.05 at 00:40:17(18862)
It is called "Cross incompatibility". It doesn't occur in all aroids, but a few
species. Pollination with mix pollen might help in some case. Delay
pollination (pollinate toward the end of anthesis time just before the stigma
surface no longer sticky) might worth a try.

Quoting Brian Williams :

> I have been working on breeding aroids for many years now. I have found

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From: <ju-bo at msn.com> on 2009.01.05 at 02:22:26(18863)
Dear Brian,

Because GOD--and some aroid freaks around (I GUESS I am one of them) don`t like hybrids!  :--)

Seriously, I`m certain that others will explain the ''whys'' of this ''reluctance'' of a ''good'' species to ''reject'' the pollen of another seemingly related species, but if there were not these ''barricades'' would`nt you think that pretty soon there would only be ONE species "left standing"?

Julius

> Date: Sun, 4 Jan 2009 17:35:51 -0500
> From: pugturd@alltel.net

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From: "derek burch" <dburch23 at bellsouth.net> on 2009.01.05 at 11:15:03(18866)
Brian,

It isn't that uncommon in other families for self fertile plants to reject
foreign pollen - not very smart from the point of vies of maintaining
diversity, but plants are not really noted for their long-range planning.

The incompatibility can take many forms - chemical rejection, chemical
incompatibility, even physical rejection. I remember working in the orchid
genus Brassavola where 'foreign' pollen (same genus, different species)
would fail on some species in which the pollen tube had to grow a long
distance from the stigma down the style to the ovules, when the pollen just
did not have the stamina to grow that far.

I'm sure that someone with more experience with aroids will have ideas on
this. Do you see any beginnings of swelling of the ovule? In that case, some
sort of "green pod" (as its called in orchids) tissue culture might bring
the embryo to maturity. In this case the pollen tube would have reached the
ovule and fertilized it, but other chemical factors would have come into
play to stop further development.

Getting seeds to form, mature and germinate is a very complex business with
many, many things that can go wrong (and only one chance to go right).You
might be better off forgetting your plant-breeding dreams and playing the
lottery.

Regards, Derek

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From: Brian Williams <pugturd at alltel.net> on 2009.01.05 at 23:39:05(18872)
It looks like the pollen of this plant is good on other plants in the
same genus but no pollen from the other species seems to work with it. I
am guessing I will have to back cross the hybrids back to the this plant
the father.

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From: Brian Williams <pugturd at alltel.net> on 2009.01.05 at 23:48:03(18873)
Derek so far their does not seem to be any berry growth at all. I am
thinking the pollen tube is unable to reach the ovules.
I have my lottery numbers each week. Fingers always crossed.
I have been successful in producing a lot of things I have been after
personally. Specially in the canna breeding and as well in my aroid
breeding. I am not sure if any will make me rich but I have enjoyed the
process and the out comes so far.

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From: "Culture Sheet" <team at culturesheet.org> on 2009.01.06 at 04:24:46(18875)
Brian,

just a thought, don't really think it applies to this genus but you
might be interested:

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From: "mossytrail" <mossytrail at hctc.com> on 2009.01.06 at 16:12:26(18876)
> It isn't that uncommon in other families for self fertile
> plants to reject foreign pollen - not very smart from the
> point of vies of maintaining diversity, but plants are not
> really noted for their long-range planning.
>
Actually, it is smart for maintaining diversity. If an
aroid accepted pollen from every congeneric species, pretty
soon the genus would have just one species -- not very
diverse. Species maintain their identities by rejecting the
pollen of other species. Diversity within species is
instead maintained by sharing pollen among different
genotypes of the same species.

Where a species DOES accept pollen from another species,
this can actually put its survival in danger. In the
April-June 2008 issue of _Madrono_ there is an article about
this: a rare, endemic evening primrose, already endangered,
is now further threatened by an escaped garden species --
they are hybridizing, and the endemic is thus at risk of
losing its identity. Unless the hybridization can be
stopped, the two species will soon become one -- a reduction
in diversity.

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From: "mossytrail" <mossytrail at hctc.com> on 2009.01.06 at 16:34:35(18877)
> I know this may open a box of worms, but I am curious if
> these plants are said to evolve from one another then why
> are these barricades even present? I can see this being
> more difficult for other genus but for different species
> it seems very odd. You would think more genus crosses
> would be more frequent and not as rare as they seem to be
> as well. Just my thoughts.
>
That is part of the speciation process. As long as two
forms are still interfertile, someone can argue they are
still the same species. Two subspecies become two species
when they lose the ability to interbreed.

As far as evolution, actually very little of it is the
result of hybridization. Rather the opposite: two
populations become isolated, and accumulate different
mutations in the different locations. This acumulation of
mutations eventually makes them different enough that they
can no longer interbreed -- at which time we say they have
speciated.

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From: <ju-bo at msn.com> on 2009.01.07 at 02:28:49(18878)
Dear Brian,

I was just kidding---do what makes you happy. 
Concerning a ''lot of species being 'natural hybrids", I don`t believe that, but it will take someone more patient and knowledgable to explain that to you.   Maybe next Sept. you and Dr. Croat or John Banta can get into a discussion on that topic.  Till then, good luck with your work!

The Best,

Julius

> Date: Tue, 6 Jan 2009 02:39:05 -0500
> From: pugturd@alltel.net

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