About # of K, species and subspecies

[Gerry Webster]

I'm not willing to engage confrontational religious debates concerning your belief systems on crocus taxonomy ......

"Religious"     

[Martin Baxendale]

I'm not willing to engage confrontational religious debates concerning your belief systems on crocus taxonomy ......

"Religious"     

I think that's meant as religious-like, rather than literally religious.

[Gerry Webster]

I'm not willing to engage confrontational religious debates concerning your belief systems on crocus taxonomy ......

"Religious"     

I think that's meant as religious-like, rather than literally religious.

"religious-like"

[Martin Baxendale]

I'm not willing to engage confrontational religious debates concerning your belief systems on crocus taxonomy ......

"Religious"     

I think that's meant as religious-like, rather than literally religious.

"religious-like"

Just my interpretation of what was being suggested, not my view. 

[Martin Baxendale]

Of course if you were trying to breed an extra-large commercial bulb like C. sativus now, finding tetraploids and crossing them to produce more tetraploids, from which you could select bigger and bigger plants would be the way to go. Deliberately producing triploids isn't the best idea as their sterility makes them difficult or impossible to use for continued further breeding for increased size.

[Janis Ruksans]

Triploids tend to be very vigorous, growing more strongly and increasing faster. In the bulb world, they are often selected out for those properties. It's more likely that a triploid crocus with strong commercial value would have been spotted and selected as a chance seedling rather than having been deliberately bred, especially if we're talking way back in history when nothing much was known about genetics, including the ploidy level of plants. A Tetraploid C. sativus would not necessarily have been bigger or have had bigger stigmas. The triploid offspring would quite possibly have been bigger and stronger than the tetraploid. I can't explain exactly why this is often the case, but it seems it is.

Too "much" genetical material quite often has side effect of depressing. In Tulips triploids are very vigorous and excellent growers, but sterile. Tetraploids are "fatter", but not so vigorous as triploids. There are very few tetraploid tulips introduced, but they can be used for creating triploids, although in tulips tetraploids has reduced fertility, too.

Janis

[Martin Baxendale]

That's interesting, Janis. I think it would probably be the vigour and multiplication rate of the triploid that was most important with a food crop like C. sativus, especially as the "harvest" is the comparatively small stigmas - a vigorous triploid version which multiplied fast, allowing fields full of the bulbs to be bulked up, would be a very desirable development.

[Croquin]

Thanks to all of you guys, I will answer/discuss about your messages below.

Gerry, no offense and my apologies if my command of english is not rendering my thoughts correctly.
Using this term is of course to tease you a bit though 
If you had to rely purely on morphological traits, how would you categorize Syringodea longituba for instance ?
I think that I am not able to enter the debate because I don't have the knowledge for it, but I can see the issues and also that any position is not 100% correct.
My remarks were more to bring relativeness and try to keep the focus on the issue I've raised rather than deviate the discussion on another debate or level of the debate.

Triploids tend to be very vigorous, growing more strongly and increasing faster. In the bulb world, they are often selected out for those properties. It's more likely that a triploid crocus with strong commercial value would have been spotted and selected as a chance seedling rather than having been deliberately bred, especially if we're talking way back in history when nothing much was known about genetics, including the ploidy level of plants. A Tetraploid C. sativus would not necessarily have been bigger or have had bigger stigmas. The triploid offspring would quite possibly have been bigger and stronger than the tetraploid. I can't explain exactly why this is often the case, but it seems it is.

That's interesting, Janis. I think it would probably be the vigour and multiplication rate of the triploid that was most important with a food crop like C. sativus, especially as the "harvest" is the comparatively small stigmas - a vigorous triploid version which multiplied fast, allowing fields full of the bulbs to be bulked up, would be a very desirable development.

I have here strains of C. sativus varying greatly in growth and corm production. One strain will give unsually 3 corms (big, big-medium, medium) + one or two cormlets, and another strain will usually give one medium corm, 6 small corms, and an important amount of cormlets. All are triploid C. sativus.
I guess that the second strain has been selected by growers cultivating C. sativus for the business of corms production.
Saffron producers usually select the biggest corms because they will give more flowers with bigger/longer stigmas also having increased chemical concentration for a better spice quality.
Also, depending on the strain, the stigma size will vary.
You may need up to 250 flowers for getting 1g of spice with one strain, and only 120 flowers with another strain.

It seems that the most probable crossings giving birth to C. sativus were C.cartwrightianus X C.cartwrightianus or C.cartwrightianus X C. thomasii, but the last two crocuses are not distributed on the same territory. It would mean that some ancient Greek croconut grew them in his garden and bees hybridized the plants ?

If the first case (C.cartwrightianus X C.cartwrightianus), why is this not observed more frequently in nature ?

You guys are all passionate and crocus lovers, didn't you try to hybridize these crocuses and checked if anything interesting was appearing ?

Too "much" genetical material quite often has side effect of depressing. In Tulips triploids are very vigorous and excellent growers, but sterile. Tetraploids are "fatter", but not so vigorous as triploids. There are very few tetraploid tulips introduced, but they can be used for creating triploids, although in tulips tetraploids has reduced fertility, too.
Janis

It sounds correct. If adding ploidy was only bringing advantages, polyploidy would be generalized and we would naturally find plants with high multiple stocks of K.

[Martin Baxendale]

It's interesting how different ploidy levels have influenced breeding in different genera. According to Janis, triploids have played a major role in tulips, and tetraploids much less so. In narcissus it's the other way around - most large garden narcissus are derived from tetraploid breeding lines, while triploids have been far less important (although quite important in developing vigorous smaller narcissus like N. 'Tete a Tete').

[Croquin]

What about crocuses ?
Has any one of you seen, cultivated, or created tetraploid crocuses ?

Tetraploids: aren't they potentially very interesting for building more complex flowers regarding shapes and colour, and not only size: you can have 4 different versions of a same gene instead of 2 like in diploids (for instance red+white giving pink).
This may allow richer combinations ?

That's my speculation, has it some reality ?

[Tom Waters]

In expressions like "2n=24", n does not represent the number of chromosomes in a single set; by convention n is just half the number of chromosomes in a normal somatic cell. It represents the number of chromosomes in a single set only if the plant is a diploid. The symbol for the number of chromosomes in a single set is x, rather than n. So you will sometimes see 2n=3x=24 for a triploid, or 2n=4x= some number, for a tetraploid.

It is possible for a single species to have diploid, triploid, or tetraploid forms, or to have forms with one or two more or fewer chromosomes (aneuploids). These variations do not constitute new species, as different species must be separated by many generations of separate evolution.

[Tom Waters]

A couple other comments: while chromosome counts can often give an indication of whether two plants can cross and produce fertile offspring, this is not an absolute rule. What matters is whether most of the chromosomes are sufficient alike (homologous) to pair. In closely related plants, this may be true even if the number of chromosomes is not exactly the same. And if the plants are very distantly related, the chromosomes will not be homologous even if by chance each plant has the same number.

[Croquin]

Thanks Tom,

do you mean that Crocus pallasii for instance, can theoretically interbreed its subspecies despite their different chromosom number provided that the gene content of these K must be very similar ?

I am not sure if this is a taboo Q that I asked, but I'm sure that some of you cultivate these subspecies of C. pallasii: were you able to cross them successfully ?
This would answer many things.

[Tom Waters]

The only way to know is to try, but it wouldn't surprise me if they were interfertile, to some extent at least. In irises (which I know better than crocuses), for example, the regelia species Iris korolkowii (2n=22) crosses readily with all oncocyclus species (2n=20), and most of the offspring are perfectly fertile.

[Croquin]

Tom,

from what you have written, it seems that K mismatch is not really an issue in plant reproduction (at least, so long it stays within certain limits).
This brings some liberality in crossbreeding species that may be of consequences.

K mismatches is the best explanation scientists offer regarding the sterility of C. sativus - together with pollen deformations.

I tend to agree that depending on the combinations of K during fecundation in C. sativus, there should be some amount of wastes.
But also, successful matches are not impossible statistically although odds are small, and from your inputs, it seems that the amount of viable combinations should be higher than that of perfect match because of this mismatch liberality.

Now, I also guess that if the fruit of a plant only bares one or two embryos, it may abort - does it ?