Transposons and Color was Virused Bulbs

Shirley Meneice
Wed, 09 Apr 2014 19:59:56 PDT
Leo, thanks for a wonderful and useful explanation.  We neophytes really
appreciate this type of information.
	Shirley Meneice

-----Original Message-----
From: []
On Behalf Of Leo A. Martin
Sent: Wednesday, April 09, 2014 6:23 PM
Subject: [pbs] Transposons and Color was Virused Bulbs

To my understanding, many cultivated flowering plants with colored or white
flowers on different plants reveal simple Mendelian inheritance of pigment
production. That is, the wild type plant has colored flowers, reflecting one
functioning set of color genes on each of the pair of chromosomes governing
flower color, whereas white-flowered plants have two sets of defective
pigment production systems. Having two of the same gene complexes is
referred to as being homozygous and having one normal and one abnormal is
referred to as being heterozygous. So, plants having two functioning
complexes would be referred to as being wild type homozygous, plants with
two abnormal complexes would be referred to as being aberrantly homozygous,
and plants with one of each would be heterozygous.

In some cases plants having one chromosome with functioning pigment genes
and one without functioning pigment genes (heterozygous) have the normal
flower color, and in other cases they have paler flowers (think red, white
and pink in sweet peas / Lathyrus

If two wild-type homozygous plants breed, all their progeny will have normal
flower colors (barring new mutations.) If two aberrantly-homozygous plants
and white flowers breed, all their progeny will have white flowers. If one
wild-type homozygous plant breeds with one homozygous-aberrant plant, all
the progeny will be heterozygous, with one normal gene complex and one
abnormal gene complex, and all will have colored flowers, since all will
produce some pigment. But if two of these heterozygous plants breed, a
quarter of their progeny will be wild-type homozygous, a quarter will be
aberrantly homozygous, and half will be heterozygous.

How them to explain flower color in Bombax ellipticum? (Or perhaps
Pseudobombax ellipticum.  I haven't read the paper.) This is a tree from
Mexico with a large under- and above-ground storage trunk. For years it was
in Bombacaceae, but a lot of reassortment has been going on, and I think it
is now a kind of cotton. Everybody I know who has been to habitat during
bloom season says all the trees have white flowers.
Almost all its American relatives have white flowers. But there is a form,
planted rarely here and there throughout Mexico, always in cultivation, with
red flowers. It can be seen at the four corners of one of the town squares
in Tehuantepec, and in at least one private garden each in Oaxaca city. This
red form does not have the thick bulbous base of the wild type, and it seems
to me the red ones are all cutting-grown. The red form has similar flowers
and leaves to the white form. I know there is a red-flowered tree in
Bombacaceae from tropical Asia, but the Mexican plant does not look to me
like photos I have seen of this species.

How to account for a plant with wild-type white flowers and one instance of
a red sport?
Transposons revealing function in an otherwise-silenced red pigment
production gene complex? I don't have the red form so I can't perform
crosses to see what happens. I know a number of people in metro Phoenix with
blooming wild-type Bombax ellipticum.

Leo Martin
Phoenix Arizona USA

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