I wrote a diary last Thursday about a herd of cows in Texas getting gassed to death in their pasture, and published it at the exact moment the SCOTUS released their ACA ruling. Surprisingly enough, it got rescued and even spent time of the wreck list. Lots of people seem to have been as curious about this bermudagrass cultivar as I was, some interesting and educational exchanges were had.
My sister the plant physiologist did weigh in on Saturday. She was as confused as I was about how the chromosomes from two different species got crossed in a petri dish for clonal cultivars (without manipulating the genes directly), as breeding wasn't her specialty all those years ago. She did give me hints on the chemicals to research, which led me to the cell culture mediums and regeneration of tissue from those that could be grown into new plants with mixed chromosomes. Which is apparently how Tifton 85 - the pasture grass in question - came about.
So I wrote about what I'd learned of this laboratory technology and included some more links. Published to my blog under the title The Great Tifton 85 Cyanide Poisoning Mystery, so please forgive some re-hashing of info from that first diary. I re-publish here as follow-up to those who were interested, so we'll all have some idea of how this kind of plant breeding works, and what - exactly - it takes to qualify as a Genetically Modified Organism.
The Great Tifton 85 Cyanide Poisoning Mystery
Most people interested in various odd and unusual happenings in the world of genetically modified organisms [GMOs] had their interest peaked in late June by news reports about 15 cattle out of a herd of 18 near Austin Texas who were gassed to death by the grass in their pasture. The government is investigating.
The gas at issue is hydrogen cyanide [HCN], a.k.a. Zyklon B, a cyanide gas pesticide also called prussic acid, most notoriously used by the Nazis to kill Jews during the Holocaust. A variety of plants - herbs, fruit trees of the prunus species, grasses and clover - normally produce prussic acid in their tissues and have been long known to poison livestock who eat too much of the wrong things. As cyanide producing plants dry after cutting or leaf fall, hydrogen cyanide is often emitted to the air as cells break down, but levels of gas high enough to kill cattle in the open air from healthy pasture grass is unprecedented - literally unheard-of. Hence The Mystery.
Original reports in the media identified the bermudagrass cultivar at issue as Tifton 85, first created in 1985 at the University of Georgia experimental station in Tifton, Georgia. The cultivar is a cross between a South African stargrass and a previously invented bermudagrass cultivar called Tifton 68. Tifton 85 is a sterile pentaploid cultivar with an odd number of chromosomes that is propagated by means of vegetative clones.
Now, this sort of terminology already gets many people seeing double about obscure plant breeding technologies, but stay with me here. I do have a point to make about this sort of genetic modification - which is NOT recombinant DNA "gene-splicing" that most who are suspicious of that technology think of when GMOs are mentioned. Claims that the poison grass is not a GMO got my curiosity going, and I've discovered quite a lot more than is normally put to use in my gardens, orchard and vineyard. Even though I do in fact clone my grape vines and apples when establishing new vines/trees, as well as cut roses so those can be added to my rose garden.
My first surprise was the seemingly overblown sensitivity of the Big Ag crowd about reports that this grass was GMO. It doesn't actually take crude gene-splicing with viral attachments, Agrobacterium tumefaciens infectors or even primitive gene gun "biolistic" genetic modification tech to produce a cultivar with a genome that could under certain circumstances de-stabilize. Which is apparently what happened to the grass at that field in Texas, where nitrogen fertilizer had been applied and the field had recently been irrigated after a multi-season drought. Something kicked excess gene sequence repeats throughout the genome into expressive overdrive - stress from the drought, nitrogen availability from the fertilizer, and the refreshing access to water to "green it all up" no doubt all played a role. The only thing that might be blamed on genetic manipulation to have established the cultivar in the first place would be the presence of so many sequence repeats (not normally expressed) responsible for the production of prussic acid in the tissues of the grass.
Thus my curiosity about how, exactly, the cultivar was originally bred without recombinant technology. The author of a blog entitled Agriculture Proud claimed Tifton 85 was produced "the old fashioned way" by shaking up some flowers from one species with some pollen from another to produce F1 hybrid seeds. But that isn't how it's done at all for sterile, clonally propagated cultivars that are sterile because they don't produce viable pollen or seeds. At least one of the parental cultivars - Tifton 68 - is exactly that.
The writer of another blog on such subjects - A Nutritionist Uses Her Degree (clever title) - made the claim that Tifton 85…
…was not produced via gene splicing or other techniques in a lab, but rather by normal, everyday breeding. Similar to crossing a horse and donkey to get a mule.
Which is total garbage as well. Donkeys and horses will mate all on their own if they can, and your basic semen in a turkey baster certainly never needed a laboratory setting. Tifton 85 needed a laboratory, a bunch of nifty chemicals and petri dishes, and a lot of artificial selection in order to become a plug-and-play means of growing turf for pastures/lawns/golf courses (how plugged turf is grown). There's nothing normal or everyday about it. It's a true artificially genetically modified organism and was since the first cells were put into the petri dish for chromosome mixing and regeneration.
How they do this is fascinating, but hardly 'normal' cross-breeding. First they culture some callus cells from each parental strain in petri dishes on a medium of agar, some fertilizing micronutrients and vitamins. When they get some viable somatic cells that can be regenerated by the 'usual' laboratory means into clones of their original source, they are mixed together in another petri dish with all the nutritional goodies previously mentioned plus some chemicals like 2,4-Dichlorophenoxyacetic acid - a.k.a. the notorious herbicide that once went into Agent Orange and is used liberally today instead of or in addition to glyphosate (Roundup). 2,4-D not only weakens and/or dissolves cell membranes, it also causes uncontrolled growth in the culture. Which will now contain cells with mixed chromosomes from both the parental cultivars (not all the same).
No Colchisine is necessary to increase the number of chromosomes, as these have already mixed in the cell culture medium to produce a variety of mixed propagable cells. [Note: Colchisine may have been used on cells from the original culture to 'double' them before regeneration. It's a "spindle poison" that would produce one cell with all chromosomes during division, and one cell with zero chromosomes. I just can't confirm that process from the available data, and a pentaploid would not seem to need doubling.] The resulting cells with chromosome pairs enough to be vegetatively viable are carefully coaxed to become plantlets, and these are grown into 'clumps' in separate pots next to each other so the breeders can see how well they do and select plants that look promising. Those are then divvied up into smaller chunks and grown as sod in little plots on the extension farm - also right next to each other - so breeders can select the healthiest, best-growing variety from the culture-to-sod process with the best overall traits. That will get marketed as the new cultivar, in this case Tifton 85.
The farmer in Texas whose cattle were gassed plugged his pasture 15 years ago with Tifton 85. He had reportedly never had a problem with it, and his cattle did well. We can expect the USDA and crop breeders at land grant universities all over the country will come up with an answer to this mystery of why the grass suddenly turned a pasture into a gas chamber. That information in itself ought to be very interesting to those of us who follow such things.
But don't let anybody fool you - Tifton 85 is very much a GMO, and it was definitely produced in a high-tech laboratory in a petri dish via cell culture and deliberate chemical manipulation to get all the 'desired' chromosomes into a single cell for future propagation. The term "Genetically Modified Organism" is not exclusive to recombinant DNA technology, and the sooner the public understands that, the sooner we can begin the real investigations and debates about what can and does go wrong with GMOs. Obviously, some of the things that can go wrong in a stressful situation - when genes may arbitrarily and suddenly turn off or on - are deadly. Cattle are bigger than most humans. It won't take as much cyanide (or whatever toxic substance could be produced by destabilized gene expression profiles) to kill us. Or even just do us serious harm.
Let's continue to talk about it. And see if we can't make the breeders/producers start telling the truth about these things for a change. THAT won't hurt them near as bad as Zyklon B will, I promise.