Do male flowers produce fruit in persimmons?

OK, here’s something more to add confusion… in that same email discussion thread, someone posted this:

“Reptiles (I think) don’t have a “sex” chromosome (gestational temp often determines sex), birds have XZ and XX (and if I remember correctly the males are the XX). Only mammals consistently are XX and XY (and even there they’ve recently found a genus of S. American mice that has XX females and XY Males and XY Females (and the XY Females appear to be “super moms”).”
I don’t know anything about that, but there was a recent Gluck Center seminar on X-Y Sex Reversal Syndrome in the horse… something I was totally unfamiliar with - though it looks, at first blush, as though these XY mares are more like a ‘freemartin’ heifer, with small, inactive ovaries & uterus, and sometimes masculine behavior.
More on that here, if interested:
XY sex-reversal syndrome in the domestic horse - PubMed.
A sporadic case of the sex-reversed mare (64,XY; SRY-negative): molecular and cytogenetic studies of the Y chromosome - PubMed

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I can’t quite agree with the XOX’O’ differentiation mechanism in persimmon. There appear to be epigenetic effects (meaning genetic expression is being changed without necessarily a change in DNA). The lack of perfect flowered persimmons supports this viewpoint.

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@Lucky_P , @Fusion_power

Here’s an article summarizing what we know circa 2019. Can you guys read it and update the above? I assume that there’s been progress since 2000.

Tao and Agaki 2019 - Sex  determination in Diospyros.pdf (520.1 KB)

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That article shows a couple of relationships but nothing that can hang on the wall to be proud of. They found an unusual ratio of 2 females to 1 male in the offspring of a selected cross of D. Lotus. Their work does not explain this ratio as they state. They found a gene that suppresses expression of a feminizing gene and were able to show it acts as an on/off switch for development of female flowers. They found plants where the female suppressing gene was not suppressing female flower expression which indicates another gene is overriding the male gene expression. Most important, they did NOT show how a polyploid like D. kaki expresses polygamous flower development. It is important to note from their work that D. Kaki is not truly monoecious (having both male and female flowers) but instead is described as polygamous meaning it develops both types of flower primordials depending on unknown triggers.

Among the most interesting items noted, other related species are monoecious. This suggests that D. kaki can be transformed with a few genetic changes to be monoecious. A monoecious D. Kaki would be highly valuable as pollinator males would no longer be needed. This can be compared with muscadine grapes which are almost all dioecious in the wild but a few monoecious vines were found which have been bred into self-fertile varieties like Ison and Paulk.

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@Fusion_power

<< That article shows a couple of relationships but nothing that can hang on the wall to be proud of. >>

Well, sure, but at least this is actual research (not mere speculation), within the same genus (not mammals or birds or reptiles).

<< It is important to note from their work that D. Kaki is not truly monoecious (having both male and female flowers) but instead is described as polygamous meaning it develops both types of flower primordials depending on unknown triggers. >>

Yeah, agreed. But this means that we shouldn’t be talking as if persimmon trees change sex due to some magical genomic gymnastics. What changes is how the genes are expressed.

That said, each variety seems to have a characteristic / most likely pattern of expression. [Caveat: I’m no botanist so consider the following to be an amateur’s attempt to recap.]. So while the species is polygamous (genotype), any individual tree may be functionally female, male, or both, and/or hemaphroditic (phenotype). So for example, Fuyu and Jiro are usually phenotypically female. Taishu is phenotypically monoecious.

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Read the article again. Half their work was done with tobacco and arabidopsis which are about as related to dispyros as humans are to shrews.

Read about epigenetics. Persimmon explicitly demonstrates that polygamy allows a tree to change sex. This is what happens when an otherwise female tree produces a branch that makes only male flowers. Plants carry all the genes necessary to express either male or female attributes. Epigenetics allows those genes to toggle under some conditions so a female produces male flowers. You simply can’t think of persimmons in the same terms you think of humans, i.e. we are born male or female and so we stay until we die. Persimmons can be either male of female or neither or both and when you think you understand this, let me know. I’m still a bit mind boggled over it.

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@Fusion_power

After reading your responses, I’m convinced that you are either being deliberately disingenuous or you don’t have the proper knowledge base to provide the context to evaluate what the investigators have done.

The research was not about tobacco and arabidopsis, per se. These species were used as transgenic carriers of genes from D. kaki. That approach was taken because there is no technology as yet for genetic transformation of D. lotus. This is a reasonable way to test how these D. kaki genes function in vivo.

<< You simply can’t think of persimmons in the same terms you think of humans, i.e. we are born male or female and so we stay until we die. Persimmons can be either male of female or neither or both and when you think you understand this, let me know. I’m still a bit mind boggled over it. >>

Yeah, I got this at least as far back as the middle of the Taishu thread, when Richard provided the Tao & Agaki (2019) article. It’s all there in black and white.

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Or I am twisting the narrative so that it more properly expresses what is happening in a plant reproductive system. Which suggests maybe you don’t quite understand it as well as you think you do. Lucky did his best to say that persimmon reproduction follows a different set of rules using comparisons with systems that don’t fit a typical male/female model. Guess what. Persimmon does not fit a male/female model.

Here is a good one to think about. Persimmon often sets hermaphroditic flowers which are described as “never producing seed” and developing 'parthenocarpically". Ask yourself why these flowers don’t pollinate and produce seed? Ask another question, why do these flowers produce fruit at all? Then go back and read the articles that attempt to shed light on what is happening. Now ask the important question, why would a tree go to the trouble of producing reproductive structures that can’t possibly reproduce? What does the tree gain from producing fruit sans seed?

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<< Here is a good one to think about. Persimmon often sets hermaphroditic flowers which are described as “never producing seed” and developing 'parthenocarpically". Ask yourself why these flowers don’t pollinate and produce seed? >>

Based on my reading of the scientific literature, I think you’ve got this wrong. What I’ve read is that hemaphroditic flowers often produce small abnormal seedless fruit and sometimes produce larger normal seeded fruit. Evidently you missed this tidbit in the article from Tao and Ogaki:

<< Hermaphrodite flowers of most D. kaki cultivars or genotypes do not fully function as female flowers because they develop seedless fruit. However, in some individuals, normal fruit containing seeds develop from hermaphrodite flowers. >>

Presumably such hermaphroditic flowers are the “male” flowers that @Barkslip reports fruiting. Indeed, this whole confusion about whether “male flowers produce fruit in persimmons” appears to have resulted from a misidentification of (fruiting) hermaphroditic flowers as male.

But the bigger reality is that nature is not always 100% efficient. If the tendency to produce hermaphroditic flowers is a waste of energy, it probably arose by chance and it may take millennia before “survival of the fittest” eliminates that trait. Or it may be a vestige of something that was once useful, and evolution has not yet caught up. You know, we still have vestigial muscles that once let us wiggle our ears like dogs.

<< Ask another question, why do these flowers produce fruit at all? Then go back and read the articles that attempt to shed light on what is happening. Now ask the important question, why would a tree go to the trouble of producing reproductive structures that can’t possibly reproduce? What does the tree gain from producing fruit sans seed? >>

Given the above, your premise [“can’t possibly reproduce”] is false. Hermaphroditic flowers in persimmons can produce viable seeds.

Nevertheless, this is an interesting question, not unique to persimmons. In persimmons, energy may be wasted on flowers that mostly will not produce. In many species as well, such as persimmons, figs, and bananas, fruit is produced without seeds. Why?

One answer is that in nature, a pollinator is normally present. The persimmon in Asia or the common fig in the Mediterranean has the capability to fruit parthenocarpically but it rarely does, as it is usually pollinated.

A second answer is that parthenocarpic varieties are cultivated by humans! The persimmon or fig in Rhode Island has a simple reproductive strategy – There’s no need for seeds. Just produce tasty seedless fruit and this hedonistic human will manage reproduction vegetatively! Hence cuttings, air layers, grafting, etc.

This last strategy works so well that there are lots of seedless plants that are 100% dependent on humans for their survival. The modern banana is an example. I’m sure you can think of many more.

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Didn’t miss it. Deliberately left it so you could mention that some hermaphrodite flowers produce seed.

Yes, and some of us can wriggle our noses, horses have dewclaws, pandas have vestigal claws, an abundance of examples can be found where nature is not quite finished with the genetics.

It is possible the seedless fruit attracted attention away from fruit having seed thereby allowing seeded fruit to escape being eaten and therefore able to reproduce. I lean more toward the opinion that it is because nature has a long way to go in revising the persimmon genome. As I stated once already, it would be very interesting if we could transfer the genes for monoecious flowering from a persimmon relative.

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Don’t know why this thread popped up…

One side comment not related to persimmons and their sexual habits.

Not all ‘fruit’ we refer to comes from the ovary of a flower.

Apples, pears, and strawberries are examples. They are accessory fruits formed from a different part of the flower.

If you look at a sliced apple you will see a papery ring around the seeds (in cross section). That is the ovary containing the seeds.

The flesh of an apple or pear is made for the thalamus of the plant… Basically the stem part just behind the flower… As is quite obvious when you see first swell of a pollinated fruit, the fruit starts forming behind the flower.

Just a fun note…

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btw is all this persimmon gender stuff settled?
I’m curious how i can explain this stuff to a friend.
Something like:
“Most grafted American persimmon we buy at nurseries are considered females but I guess are actually hermaphrodite (male+female parts on the same flower?) and hence able to make fruit. Some varieties like Meader/Szuki/EarlyGolden” can make limbs that are pure male flowers to populate pure female flowers."
Note that Im only interested in the large-fruited American Persimmon you see in nursery catalogs (not sure if those are the 90 or 60 chromosome version , assume 90).

i don’t think so, not by a long shot. speculation abounds.

All fruit comes from ovaries. The difference is the location of the carpel - the part containing the ovules from which the fruit is formed.

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That’s not the case as I’ve read and heard (botanist podcast) that the bulk of the flesh from an apple is an accessory fruit, not developed from the ovary.

applefigures-004

i see what youre getting at. the part we eat isnt the fleshy pericarp, but swollen thalamus. funny how imprecise our language is in common use vs botanical fact. vegetable means something to everyone yet is not a botanically meaningful descriptor. Even though fruit is closer to botanical fact, youre sort of pointing out that theres still a gap there. lots of fruits wouldnt fit our understanding of the word: a walnut fruit (husk), samaras.

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It’s fascinating stuff. If you’re working in the garden or going for a long drive I recommend listening to this podcast about the evolution of fruit.

The ladybugs a paleobotanist guest on the show. Skip to the main discussion at 37:05.

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I recently ordered its sibling F- 90 a fruiting male and you already know why and what my goal is.

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Is there a list of asian varieties that produce male flowers and if they produce “a lot” of male flowers? I’ve read chocolate produces plenty of male flowers, but what else?

TIA!

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