Proposal to evaluate genetic tools to evaluate Cattleya species

[geoffsharris]

Geoff, if the total DNA content by flow cytometry is going to be detectably different between species I can see that a tetraploid will have 2x the DNA of an established type species and be easy to identify and probably impossible to confuse with hybridization with any other species because none should have enough DNA to get that high. However, as we get to triploids and "mixaploids", I am thinking that we couldn't reliably distinguish these from hybrids with another species? They would be identified as "non-diploid" but we couldn't be sure what.

Terry, I agree that this would (hopefully) be most useful for telling if a plant is diploid or tretaploid and is likely the target species or not. There is some potential for people to have plants that are triploids (as a result of breeding 2n x 4n plants). This case would potentially require further evaluation of what the possibilities are for it being 3n or a hybrid. Could easily figure this out for plants with completely unknown parents which might include a root tip squash for confirmation. Mixaploids I think are pretty uncommon based on the data I've seen to date. This could occur at a higher rate in some of the really weird plants and explain variable behavior from bloom to bloom as the plant could have an unstable genome or actually be a chimera, but these would be very rare plants.

I agree the proposal has its limits in terms of what this information may or may not be able to do. My goal would be to make it easy for people to figure out if their plant is diploid or tetrapoid and likely the species or a hybrid (or something weird and unexpected). Certainly it will be imperfect in certain cases and may not be useful at all in others.

 

[terryros]

Got it. Establish the 2N DNA content with clear cut examples of a species that are not thought to be tetraploid or hybrids. Test some examples of the species that are thought to be tetraploid or possibly accidental or surreptitious hybrids.

 

[geoffsharris]

Got it. Establish the 2N DNA content with clear cut examples of a species that are not thought to be tetraploid or hybrids. Test some examples of the species that are thought to be tetraploid or possibly accidental or surreptitious hybrids.

Spot on. I'm super curious what we will find. I'm also speaking with my friend at Illumina. They are the biggest gorilla in next generation sequencing. There may be additional data we could capture in parallel depending on the companies that do plant genetics/genomics since we will be gathering the necessary and interesting plant source material.

 

[DrLeslieEe]

I’m interested to see what these labs can offer and what you intend to establish as the baseline plants of each species for comparisons.

Of course, you have my collection at your disposal. As well as my contacts in Japan, Asia and South America if need be.

 

[terryros]

As compared to chromosome counting, that requires cells in active division, I am thinking that we will want mature, resting cells with their diploid genome. We probably don’t want actively growing root tips or we risk too many cells that might have 4N DNA right before they divide. Do we just cut a piece of leaf and put it in a particular solution in a bottle and send it in?

To Leslie’s point, my statistics training pushes me to try and get about 11 scattered examples of the target species we pick. We want these to be as verified traditional/standard as possible, including even provenance that takes them to natural jungle collected. Natural collected doesn’t exclude tetraploids, etc, but it helps if everything else about the plant isn’t “excessive”. With 11, sort of randomly collected plants, we have a first shot at establishing a mid-point and range of the DNA content. Then we can compare with variant plants.

I am good friends with Jerry and Jason Fischer at Orchids Limited and I am sure that they would supply material from their substantial species collection.

 

[geoffsharris]

I'll work on the details of what the ideal sample will be. You are correct Terry. We will likely need a small piece of mature leaf that isn't actively growing to minimize capturing a lot of cells with duplicating chromosomes. Orchids grow slowly, so even in such a case it probably would change things much. The idea of tracking down high probability diploid, true species plants in sufficient numbers is a very good idea. I think there are a number of people that we could enlist in this. Jerry&Jason would certainly have useful plants. Chadwicks and Fred Clarke come to mind as well.

 

[DrLeslieEe]

Don’t forget David Off, Steven Kristoffersen, Lin Burzell, Jeff Bradley, Robert Fuchs and Ben Oliveros. Also Sergio Garcia and Michael Sinn, all with known jungle plants pre CITES.

 

[terryros]

I think Geoff and Leslie are best positioned to decide on a first test species. I think one with easy access to clear-cut diploid plants AND one that also has at least a little group of questionable plants that could be compared.

 

[DrLeslieEe]

I think walkeriana or mossiae are good choices to start with.. both have suspected hybrids in their ilk.

 

[DrLeslieEe]

Any updates Geoff re your lab searches?

 

[geoffsharris]

I've been on vacation for a few days. Will be working on labs next week.