Agave Ploidy

[Gee.S]

Please feel free to add any ploidy information regarding specific agave species to this thread, and I'll maintain it as an alphabetical list.

A. ×ajoensis (schottii × simplex): 3x
A. americana: 2x
A. americana var. marginata: 4x
A. angustifolia: 2x
A. angustifolia var. marginata: 2x
A. ×arizonica (chrysantha × (diploid) toumeyana): 2x (there is also a tetraploid toumeyana incarnation)
A. attenuata: 2x
A. avellanidens: 2x
A. cantala: 3x
A. chrysantha: 2x
A. colorata: 2x
A. cupreata: 2x (three studied population) but 4x, 5x, 6x (one studied population)
A. decipiens: 6x
A. delamateri: 4x
A. deserti: 2x
A. deserti var. simplex: 2x
A. filifera: 2x
A. fourcroydes: 2x and 5x
A. gigantensis: 2x
A. lechuguilla: 4x
A. marmorata: 2x
A. murpheyi: 2x
A. palmeri: 2x
A. parryi: 2x
A. parryi subsp. neomexicana: 2x
A. parviflora: 2x
A. ×peacockii: 2x
A. phillipsiana: 4x
A. potatorum: 2x
A. schottii: 4x, though I have also encountered at least one 2x example
A. schottii var. treleasei (chrysantha × schottii): 3x
A. shawii subsp. goldmaniana: 4x
A. sisalana: 5x although A. amaniensis which has been synonymized is reported to have: 2x
A. tequilana: 2x and 3x
A. toumeyana var. toumeyana: distinct 2x and 4x pops
A. toumeyana var. bella: distinct 2x and 4x pops
A. utahensis subsp. kaibabensis: 2x
A. utahensis subsp. utahensis: 2x
A. verdensis: 2x
A. yavapaiensis: 2x

[jam]

I have updated your list, Ron. Additions in bold.

A. ×ajoensis (schottii × simplex): 3x
A. americana: 2x
A. americana var. marginata: 4x
A. angustifolia: 2x
A. angustifolia var. marginata: 2x
A. ×arizonica (chrysantha × (diploid) toumeyana): 2x (there is also a tetraploid toumeyana incarnation)
A. attenuata: 2x
A. avellanidens: 2x
A. cantala: 3x
A. chrysantha: 2x
A. colorata: 2x
A. cupreata: 2x (three studied population) but 4x, 5x, 6x (one studied population)
A. decipiens: 6x
A. delamateri: 4x
A. deserti: 2x
A. deserti var. simplex: 2x
A. filifera: 2x
A. fourcroydes: 2x and 5x
A. gigantensis: 2x
A. lechuguilla: 4x
A. marmorata: 2x
A. murpheyi: 2x
A. palmeri: 2x
A. parryi: 2x
A. parryi subsp. neomexicana: 2x
A. parviflora: 2x
A. ×peacockii: 2x
A. phillipsiana: 4x
A. potatorum: 2x
A. schottii: 4x, though I have also encountered at least one 2x example
A. schottii var. treleasei (chrysantha × schottii): 3x
A. shawii subsp. goldmaniana: 4x
A. sisalana: 5x although A. amaniensis which has been synonymized is reported to have: 2x
A. tequilana: 2x and 3x
A. toumeyana var. toumeyana: distinct 2x and 4x pops
A. toumeyana var. bella: distinct 2x and 4x pops
A. utahensis subsp. kaibabensis: 2x
A. utahensis subsp. utahensis: 2x
A. verdensis: 2x
A. yavapaiensis: 2x

references:
G. Palomino, J. Martínez, V. Cepeda-Cornejo & E. Pimienta-Barrios (2017) Nuclear genome size and cytotype analysis in Agave cupreata Trel. & Berger (Agavaceae) for A. cupreata
G. Palomino, J. Dolezel , I. Mèndez & A. Rubluo (2003) Nuclear genome size analysis of Agavetequilana Weber, Caryologia: International Journal of Cytology, Cytosystematics and Cytogenetics, 56:1, 37-46 for the rest

[Gee.S]

^^ Excellent.

[Papahuel]

https://www.researchgate.net/figure/Plo ... _261619732

I read this a while ago that shows various varieties of tequiliana are, 2x 3x 4x & 5x (but predominantly 2x followed by 3x)

[plantguy]

So, is it because there are pops of aneuploid fourcroydes that people say it is a sterile plant? In which case, does that mean there are fertile populations of fourcroydes as well? And are they more or less common? Also, any idea to the ploidy of franzosinii?

[Miguel]

These information are very interesting.
Thank you for sharing.
Does anyone have experiences which influence the ploidy grade have, if you cross two agaves.
My experience is, that it works with some agaves, but not with all, depending on both agaves, that were crossed. Is there a rule for that?
Not easy to get an overview, because information for many agaves is not available. Some are self-fertile, others not. Sometimes cross-pollination works, sometimes not.
Would be interesting for me to get more information about.

[MJP]

In theory,
a plant is sterile (cannot produce viable gametes) if its ploidy level is not 2 or another even number (2, 4, 6, 8 . . . ).

Plants of odd-number ploidy level (3 or 5 for instance) usually occur as a result of hybridization of parents of different ploidy level.
A diploid parent (2n) produces gametes (1n), that when combined in fertilization create a diploid (2n). 1n + 1n = 2n.

Similarly, a tetraploid parent (4n) produces diploid gametes (2n). In usual cross-fertilization we'd have 2n + 2n = 4n.
However, if the 2n pollen fertilizes a 1n ovule, then we have 2n + 1n = 3n, and the result is a triploid offspring that is sterile. [Its gametes would be half of 3, which is 1.5, and so a partial set of chromosomes].

Hybridizers can and do use this knowledge to produce sterile hybrids. It means no one can use these hybrids for further hybridization, and the original hybridizer is thus in control, as it were. Christmas Cacti are exemplary of this method.

Increased ploidy level above 2n usually occurs when meiosis fails to produce the usual 1n gametes, and instead produces an unreduced gamete of 2n. Although this may be a random occurrence, chance allows that eventually two unreduced gametes will meet, and the result will be a tetraploid offspring.

The happenstance of error in meiosis also sometimes occurs in polyploids of odd number (3n, 5n what have you), so that on occasion they will produce an unreduced gamete that is therefore viable and able to pollinate or be fertilized (if the gamete encountered is of the same ploidy level as the unreduced gamete).

So, the world of polyploids is endlessly fascinating from the views of mathematicians, biologists, and hybridizers.

For taxonomists, its is a conundrum. Should polyploids be treated as separate species or as a larger complex species taken as a whole?

Life is flowing conditions thing whilst it lives.
It is ever interesting and beguiling.

[MJP]

I meant to finish by writing:

Life is a flowing continuous thing whilst it lives.
It is ever interesting and beguiling.

[Papahuel]

Any ideas for weberi?

Things are slowly approaching and I'm contemplating what hybridisation I would like to go for and weberi is one of the best contenders and amazingly left alone by the wildlife despite the almost complete lack of marginals.

So hybrids that are 2n + 2n, 4n + 4n and 2n + 4n are usually a go is that correct?

[Gee.S]

Any ideas for weberi?

Things are slowly approaching and I'm contemplating what hybridisation I would like to go for and weberi is one of the best contenders and amazingly left alone by the wildlife despite the almost complete lack of marginals.

So hybrids that are 2n + 2n, 4n + 4n and 2n + 4n are usually a go is that correct?

Sure, except the latter would produce sterile triploids. And sorry, but no clue on weberi, which doesn't produce viable pollen here due to the heat.

[Papahuel]

Thanks, I'm surprised the domesticates are mainly 2x (and 4x), why are they so reproductively compromised?

Also forgot to ask about karwinskii on ploidy?

So far potatorum, tequiliana, weberi, karwinskii and my unresolved Caribbean quick flowerer are the top picks for potential "passing ships in the night".

[Gee.S]

Thanks, I'm surprised the domesticates are mainly 2x (and 4x), why are they so reproductively compromised?

Also forgot to ask about karwinskii on ploidy?

So far potatorum, tequiliana, weberi, karwinskii and my unresolved Caribbean quick flowerer are the top picks for potential "passing ships in the night".

Everything I've been able to discover ploidy-wise is in the OP.

I have no idea how the domesticates were reproductively compromised, but it was certainly no accident. I jokingly refer to this as horticultural voodoo. These folks may have been so horticulturally advanced that their efforts seem like magic to us modern day savages. I elaborate on this to some small extent in Part 2 of the 3 part article I penned a year or two ago for CSSJ, and posted on this forum.