RE: HTD: Maternal Inheritence

It is helpful also to remember the nuclei of the endosperm and seedcoat too
are "triploid" (relative to the n value in the nucleus) with double
inheritance from the female parent.

Since we're dealing with tetraploids, the nucleus is tetraploid, the endosperm
and seedcoat nuclei are hexaploid--a difference that makes no difference
relative to what happens in diploids as far as the question of maternal
dominance is concerned.

Since two-thirds of the inherited nuclear genetics in the parts of the seed
outside the embryo is from the mother, maternal dominance of seed germination
factors is not surprising.

In addition to the matter resulting from the fertilization process giving the
nuclei of the endosperm 2/3'ds of the genetics from the mother, it is
important to remember that the non-nuclear structures of the endosperm are
entirely from the mother, none from the father.  Thus the maternal parent
influences the germination process even more.

Chuck Chapman's comment about watching ratios for difficult vs. easy
germination is apt.  However, it is important to remember that if the delayed
germination is generated by control from the nucleus of the embryo, the
influence is half and half maternal/paternal.  If the delay is caused by
actions in the nuclei in the endosperm or seed coat cells on the other hand,
the influence is 2/3'rds maternal to 1/3 paternal in origin.

If, in a third possibility, the delayed germination is determined by
conditions or factors in the seed coat or endosperm tissue other than the
nucleus, the inheritance in irises is entirely from the mother.

There are cases in some genera and/or species where the endosperm is not
derived entirely from the mother, but this does not include irises.

Nothing like being simple, no?

Neil Mogensen  z 7 western NC mountains

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