On Thu, 5 Jun 2003 22:49:09 +0800, "John" wrote:

Is there any different in an orchid if it's seed parent and pollen parent
are swapped with each other?

That is what is the different to be the seed parent and to be a pollen
parent?

Thanks for the advice.


John,

Below are some quotes (please accept my apology for the lack of
attribution to many of them.) dealing with the subject


In "classic" Mendelian genetics, both parents simply contribute
genes to the progeny, and what the progeny ends up having depends on
the dominance/recessiveness of various genes. This case works well
for some traits, but there are other possibilities of co-dominance,
incomplete dominance, or a trait being controlled by a set of genes
as opposed to just one (human skin coloring is one of these traits,
which causes children of mixed-racial heritage to usually look like
a more-or-less even blend of the coloration of their parents). The
niggle with "classic" Mendelian models is that they only work well
when the two parents are the same species, or members of a complex
of closely inter-related species.

When you get into orchid breeding which mixes vastly different
species (or even genera), the prospect of maternity of the plants
begins to determine things more, because the genes are not the entire
story of inheritance. In the maternal ova, the mix of proteins
and other elements determines how those genes are actually applied
to the plant. Hence, the maternal plant will often show a greater
dominance of characteristics, especially when the plants are
from disparate species or genera.

Considering that you are trying to breed two Phal hybrids, which may
very well be 50% or more the same, genetically, you will likely get
a more Mendelian mix of traits. Were you to try, say, mating a
big, white Cattleya as pollen parent with an Epi. conopseum as a pod
parent, you would end up with a slightly larger, thicker, and lighter
colored flower that still strongly resembles the Epi. conopseum
parent. Many 1st-generation Epicatts show this in action, looking
like a slightly modified version of their Epidendrum/Encyclia moms
with the addition of coloration and some shape traits from their
Cattleya dad.


If we are talking only about traits linked to genes carried on the
chromosomes of the parents, it doesn't matter which parent they come
from. The capsule or pollen parent will contribute equally and
neither will be more dominant in contributing specific traits, beyond
the normal dominant/recessive characteristics of the genes involved.

EXCEPT - many orchids are not simple diploids with 2 matched sets of
chromosomes. If one of the parents is triploid, tetraploid,
hexaploid, etc. it has MORE genetic material to contribute than a
diploid counterpart and will have more influence on ALL traits.

BUT - some characteristics are not determined entirely by genes on the
chromosomes. Plastids and mitochondria also carry genes that
contribute to photosynthesis, energy processing, and green and yellow
color in flowers, for example. All plastids and mitochondria are
contributed to the seed by the capsule parent, so certain
characteristics such as light and temperature preferences, general
vigor, and some flower colors may be more influenced by the capsule
parent.

Many breeders give anecdotal evidence of capsule or pollen parents
being more dominant for certain characteristics in general, and they
may be correct. I've just tried to list some of the understandable
reasons why it may be true in particular cases.

Pink x green = white
Pink x white = green

Cells don't have organs inside. They do have organelles, though.
Anthocyanins accumulate in vacuoles. You can't simplify the site of
accumulation of red pigments and yellow pigments. Both anthocyanins
(red-purple-violet, etc) and chalcones (pale yellow) are flavonoids
and carotenoids (orange-yellow, etc) are very different from the
former. Carotenoids accumulate in chromoplasts, etc.


the theory that mitochondria are responsible for certain pigment
production in particular species. These organelles have their own
genomes. This is why certain cattleyas are yellow, but their
offspring are only yellow if that plant carries the pod. The mother is
the only parent to pass on organelles.



http://abstracts.aspb.org/pb2002/public/P73/1183.html

Anthocyanin biosynthetic genes and flower color manipulation of
Dendrobium orchids
Additional Authors
Kuehnle, Adelheid
Champagne, Michele
Affiliations: University of Hawaii

Anthocyanins are one of the major pigments found in dendrobium
flowers. A chemical survey of Dendrobium species and hybrids
showed lavender cyanidin and peonidin to be the predominant
anthocyanidin and orange pelargonidin to be rare. Our objective
is to clone and characterize the key anthocyanin biosynthetic
genes and to produce novel flower colors through genetic
manipulation. Partial cDNA clones of chalcone synthase (CHS),
flavonoid 3’5’ hydroxylase (F3’5’H) and a full clone of
dihyroflavanol 4-reductase (DFR) were isolated using cDNA from
floral buds of dark lavender Dendrobium Jaquelyn Thomas
“Uniwai Prince”. Deduced amino acid sequences of CHS and DFR
showed 84% and 90% similarity to those of the orchid, Bromheadia,
respectively. Developmental expression profiles of infloresences
showed that both DFR and CHS are expressed in all bud stages and
decline to an undetectable level just before the flower opens.
Contrary to DFR, CHS is expressed in leaves. The F3’5’H clone
showed 67% identity to that of Petunia hybrida at the amino acid
level. We have introduced the DFR gene from Antirrhinum
Dendrobium with the intention of making novel colors of red
shades. PCR and RT-PCR analyses indicated the presence and the
expression of the introduced gene. Transgenic plants are already
in the green house for flowering.