I know, of course, that edible fruit has evolved by natural selection. The
sweet-tasting fleshy fruits attract animals, who eat the fruit, spit out the
seeds, and inadvertently sow the next generation of the plant. This
evolution process may have started, millions of years ago, with a
not-very-satisfying fruit, and natural selection has caused the evolution of
the fruit into the sweet and fleshy forms we know today. The tastier and the
fleshier the fruit, the better it will attract animals to spread the seed.

My question is:- Why did the prototype form of fruit ever exist in the
first place, many millions of years ago? Why did seeds ever have fleshy
fruit around them, however thinly and however bitter-tasting, from which the
evolution process could begin? Could the flesh of the fruit have been a
botanical form of placenta, separating the DNA of the mother plant from the
DNA of the seed? i.e. performing a similar function to that of the
placenta in the animal kingdom. Is there any evidence to support this
hypothesis? Does the flesh in (for example) the modern peach perform the
function of DNA-separation, in addition to its well-known function of
attracting an animal to eat it and spread the seed?

What function does the flesh of the berry have in Deadly Nightshade? As the
berries are poisonous, the plant does not rely on animals to spread the
seed. The flesh of the berry would therefore seem redundant, unless it also
has some other function, such as a botanical form of placenta.

Richard Chambers Leeds UK.

Clearly, the presence of fleshy juicy edibles near the seed has developed
more than once, in several different lineages. DNA has nothing to with it.

The fact that the berry of nightshade is poisonous to humans does not mean
it is necessarily poisonous to all possible dispersing animals.
PvR

"Dick Chambers" schreef
I know, of course, that edible fruit has evolved by natural selection. The
sweet-tasting fleshy fruits attract animals, who eat the fruit, spit out
the seeds, and inadvertently sow the next generation of the plant. This
evolution process may have started, millions of years ago, with a
not-very-satisfying fruit, and natural selection has caused the evolution
of the fruit into the sweet and fleshy forms we know today. The tastier and
the fleshier the fruit, the better it will attract animals to spread the
seed.

My question is:- Why did the prototype form of fruit ever exist in the
first place, many millions of years ago? Why did seeds ever have fleshy
fruit around them, however thinly and however bitter-tasting, from which
the evolution process could begin? Could the flesh of the fruit have been a
botanical form of placenta, separating the DNA of the mother plant from
the DNA of the seed? i.e. performing a similar function to that of the
placenta in the animal kingdom. Is there any evidence to support this
hypothesis? Does the flesh in (for example) the modern peach perform the
function of DNA-separation, in addition to its well-known function of
attracting an animal to eat it and spread the seed?

What function does the flesh of the berry have in Deadly Nightshade? As
the berries are poisonous, the plant does not rely on animals to spread the
seed. The flesh of the berry would therefore seem redundant, unless it
also has some other function, such as a botanical form of placenta.

Richard Chambers Leeds UK.

P van Rijckevorsel wrote:
Clearly, the presence of fleshy juicy edibles near the seed has developed
more than once, in several different lineages. DNA has nothing to with it.
[...]

But Dick's question was far more reasonable than you make it sound. I'm
rather surprised, as you're generally very helpful to enquirers. Seeds
_are_ connected to the parent via a placenta: I, too, assume that's how
seeds can give rise to plants not genetically identical to their
parents. Is that right? It also seems, to a non-specialist, reasonable
to make an evolutionary connection between the placenta and the fleshy
parts: is that wrong?

--
Mike.

Mike Lyle wrote in message
oups.com...

P van Rijckevorsel wrote:
Clearly, the presence of fleshy juicy edibles near the seed has developed
more than once, in several different lineages. DNA has nothing to with
it.
[...]

But Dick's question was far more reasonable than you make it sound. I'm
rather surprised, as you're generally very helpful to enquirers. Seeds
_are_ connected to the parent via a placenta: I, too, assume that's how
seeds can give rise to plants not genetically identical to their
parents. Is that right? It also seems, to a non-specialist, reasonable
to make an evolutionary connection between the placenta and the fleshy
parts: is that wrong?

Thank you Mike. (Are you the same Mike Lyle who inhabits alt.usage.english ,
by the way?) I hope your reply will stimulate a more extensive discussion,
as I would like to know the arguments on both sides.

Another thing that puzzles me on this question is that I cannot assess
whether a fruit tree rejects "foreign" DNA tissue in the same way as an
animal (such as a human being) would. I remember, when a young child, that
my father grafted a small branch of a pear tree onto an apple tree. The
grafting worked, and there was no rejection. This must have been the
botanical equivalent of grafting a chimpanzee arm onto a human being. In the
animal kingdom, there would have been a total DNA rejection. This evidence
suggests that DNA rejection might not be so strong in the plant kingdom as
it is in the animal kingdom. So perhaps there is no need for placental
separation of the seed from the mother plant. I simply do not know, which is
the reason why I have asked my original question.

Richard Chambers Leeds UK.

Well, helpfulness has its limits, and DNA still has nothing to do with it.
PvR

"Dick Chambers" schreef
Another thing that puzzles me on this question is that I cannot assess
whether a fruit tree rejects "foreign" DNA tissue in the same way as an
animal (such as a human being) would. I remember, when a young child, that
my father grafted a small branch of a pear tree onto an apple tree. The
grafting worked, and there was no rejection. This must have been the
botanical equivalent of grafting a chimpanzee arm onto a human being. In
the animal kingdom, there would have been a total DNA rejection. This
evidence suggests that DNA rejection might not be so strong in the plant
kingdom as it is in the animal kingdom. So perhaps there is no need for
placental separation of the seed from the mother plant. I simply do not
know, which is the reason why I have asked my original question.

Richard Chambers Leeds UK.

Dick Chambers wrote:
I know, of course, that edible fruit has evolved by natural selection. The
sweet-tasting fleshy fruits attract animals, who eat the fruit, spit out the
seeds, and inadvertently sow the next generation of the plant. This
evolution process may have started, millions of years ago, with a
not-very-satisfying fruit, and natural selection has caused the evolution of
the fruit into the sweet and fleshy forms we know today. The tastier and the
fleshier the fruit, the better it will attract animals to spread the seed.

Not necessarily. Take Trillium fruits. They're sort of fleshy -- but
the attraction to the disperser is in the aril on the seed. It's full
of fatty acids and sugars; and the ants (and yellow jackets) love them.
They carry the seed off, eat the aril and leave the seed behind. The
fruit serves not only as a vehicle for dispersal, but also to protect
the seed.


My question is:- Why did the prototype form of fruit ever exist in the
first place, many millions of years ago? Why did seeds ever have fleshy
fruit around them, however thinly and however bitter-tasting, from which the
evolution process could begin? Could the flesh of the fruit have been a
botanical form of placenta, separating the DNA of the mother plant from the
DNA of the seed? i.e. performing a similar function to that of the
placenta in the animal kingdom. Is there any evidence to support this
hypothesis? Does the flesh in (for example) the modern peach perform the
function of DNA-separation, in addition to its well-known function of
attracting an animal to eat it and spread the seed?

The fruit both protects the seed and acts as an aid to dispersal.
Gymnosperms (in case you don't know, the name means "naked seed") have
only seeds with no fruit. The pine seeds are attached to ovuliferous
bracts inside the pine cone. It's similar to maple fruits in that that
scale is a papery thing so they're wind dispersed.

DNA isn't an issue is plants because of the way that plants reproduce.
In lower plants, like ferns, it's easy to see what we call the
Alternation of Generations. The fern body is diploid sporophyte tissue
-- it makes the spores. The spores then germinate into a tiny
structure called a gametophyte which produced the eggs/ovules and
sperm. Fertilization takes place, and a new fern body is produced.
The concept is an old one (Foster & Gifford give 1862) and it's the
metaphysical equivalent of cats having puppies which in turn have
kittens. They didn't know haploid and diploid -- they only knew that
the progeny of a fern was not a fern, it was this little heart-shaped
thing -- and the progeny of *that* was another fern.

The change is more fundamental though than just presence or absence of
a fruit. It's the presence or absence of an ovary. In Gymnosperms,
the ovule itself sits on that scale; in Angiosperms, the ovules are
protected inside an ovary. In most cases, the fruit then, is made of
of ovary tissue. Fruits are kinda cool -- you have diploid parent
tissue (the "meat" of the fruit) and diploid progeny tissue (the
embryo) -- and then there's the triploid endosperm).

The flesh of the fruit may be composed of different types of tissue.
In a tomato, for instance, I know that the "meat" is placenta tissue.
(that tussue that connects the seed to the ovary wall is indeed called
placenta). In a bean, the placenta is that little bitty stub that
connects the bean to the ovary wall -- and the "meat" of the fruit is
just the ovary wall. In an apple, the "meat" of the fruit is
hypanthium tissue -- the ovary wall is that tough membrane that
surrounds the seeds. Sometimes, like in Coconuts, both coconut milk
and coconut "meat" are endosperm; popcorn is also endosperm.

Plants don't have an immune system like people do, so there's no issue
with mixing the different DNAs. (As an aside, it's not the DNA that's
the problem in humans -- it's the proteins on the blood that can be
problematic. During pregnancy, the mother's immune system is
"suppressed" for lack of a better word. There's one school of thought
that thinks that it might be an immune response that triggers labor,
but I digress). There is a plant pathogen response, but it's a really
complicated mixture of virulence genes in both pathogen and host plant.


What function does the flesh of the berry have in Deadly Nightshade? As the
berries are poisonous, the plant does not rely on animals to spread the
seed. The flesh of the berry would therefore seem redundant, unless it also
has some other function, such as a botanical form of placenta.


Just because the berries are poisonous to humans, doesn't necessarily
mean that they're poisonous to other critters. I believe that birds
are the dispersers in those Solanums.

Susan

P van Rijckevorsel wrote:
Well, helpfulness has its limits, and DNA still has nothing to do with it.
PvR
[...]

That's almost a Cereus Validus response. If you didn't want to explain,
you needn't have replied at all. You've answered simpler questions than
this one willingly enough.

I know Dick from elsewhere, and he isn't a stupid time-waster.

--
Mike.

"Mike Lyle" schreef
That's almost a Cereus Validus response. If you didn't want to explain,
you needn't have replied at all. You've answered simpler questions than
this one willingly enough.

***
1. If Cereus would be making this kind of statements, he would not have had
the trouble he has encountered.
2. The original question was pretty much impossible to answer, as it
included so many wrong assumptions that it was close to a booby trap. There
was nothing simple about it.
3. I did a fair job of dismantling the booby trap, addressing most of the
wrong assumptions in the question. I cannot help it if you did not want an
answer, but only wanted to have the wrong assumptions confirmed.
PvR

Susan wrote

[ . . . ]

The fruit both protects the seed and acts as an aid to dispersal.
Gymnosperms (in case you don't know, the name means "naked seed") have
only seeds with no fruit. The pine seeds are attached to ovuliferous
bracts inside the pine cone. It's similar to maple fruits in that that
scale is a papery thing so they're wind dispersed.

DNA isn't an issue is plants because of the way that plants reproduce.
In lower plants, like ferns, it's easy to see what we call the
Alternation of Generations. The fern body is diploid sporophyte tissue
-- it makes the spores. The spores then germinate into a tiny
structure called a gametophyte which produced the eggs/ovules and
sperm. Fertilization takes place, and a new fern body is produced.
The concept is an old one (Foster & Gifford give 1862) and it's the
metaphysical equivalent of cats having puppies which in turn have
kittens. They didn't know haploid and diploid -- they only knew that
the progeny of a fern was not a fern, it was this little heart-shaped
thing -- and the progeny of *that* was another fern.

The change is more fundamental though than just presence or absence of
a fruit. It's the presence or absence of an ovary. In Gymnosperms,
the ovule itself sits on that scale; in Angiosperms, the ovules are
protected inside an ovary. In most cases, the fruit then, is made of
of ovary tissue. Fruits are kinda cool -- you have diploid parent
tissue (the "meat" of the fruit) and diploid progeny tissue (the
embryo) -- and then there's the triploid endosperm).

The flesh of the fruit may be composed of different types of tissue.
In a tomato, for instance, I know that the "meat" is placenta tissue.
(that tussue that connects the seed to the ovary wall is indeed called
placenta). In a bean, the placenta is that little bitty stub that
connects the bean to the ovary wall -- and the "meat" of the fruit is
just the ovary wall. In an apple, the "meat" of the fruit is
hypanthium tissue -- the ovary wall is that tough membrane that
surrounds the seeds. Sometimes, like in Coconuts, both coconut milk
and coconut "meat" are endosperm; popcorn is also endosperm.

Plants don't have an immune system like people do, so there's no issue
with mixing the different DNAs. (As an aside, it's not the DNA that's
the problem in humans -- it's the proteins on the blood that can be
problematic. During pregnancy, the mother's immune system is
"suppressed" for lack of a better word. There's one school of thought
that thinks that it might be an immune response that triggers labor,
but I digress). There is a plant pathogen response, but it's a really
complicated mixture of virulence genes in both pathogen and host plant.

[ . . . ]

Thank you, Susan, for the trouble you have taken in providing this
comprehensive reply. This was the level of detail I was looking for,
informing me exactly where the underlying assumptions of my original
question were incorrect. The incorrectness of my assumptions has already
been noted in less detail by Mr van Rijckevorsel's third posting - but at
least as a result of your reply I now know why they were incorrect.

Richard Chambers Leeds UK.

Dick Chambers wrote:
Susan wrote

[ . . . ]


*snippage*

[ . . . ]

Thank you, Susan, for the trouble you have taken in providing this
comprehensive reply. This was the level of detail I was looking for,
informing me exactly where the underlying assumptions of my original
question were incorrect. The incorrectness of my assumptions has already
been noted in less detail by Mr van Rijckevorsel's third posting - but at
least as a result of your reply I now know why they were incorrect.

Richard Chambers Leeds UK.

You're welcome. I actually didn't see Mr. van rijckevorsel's answer
until after I'd already answered you. I get this thing on the
metaphysical equivalent of Digest Mode ...

susan