it has already been decided

Plant pathologists are in agreement – GMO crops are safe and effective for controlling crop diseases and boosting yields. The only question is, why can’t they get their message through to the general public?

Peter van Esse works on Asian soybean rust, which is a destructive soybean disease in Brazil that is held at bay by extensive application of fungicides. The fungicide use could be reduced through breeding of resistant varieties of soybean, but there is no source of natural resistance in any known strain of soybean to breed into a crop variety. There is, however, resistance in some strains of pigeon pea, a relative of soybean, and the genes responsible for pigeon pea resistance have been thoroughly studied. Unfortunately, pigeon pea is not closely related enough to interbreed with soybean.

The technology exists for inserting the pigeon pea resistance genes into soybean. Van Esse has accomplished the transformation, and the tests show that the resulting transgenic soybeans can fight off the disease. The only obstacle is public opposition.

A colleague of van Esse’s points to an article on the topic in a social science journal – the people who know the least about GMOs are the most adamantly opposed to them. Why, they puzzle, is the public so poorly educated on the safety and benefits of GMOs?

Perhaps the question should be, is it any wonder? Science has a track record of making authoritative pronouncements, only to reverse them upon further study. Only N95 masks work against coronavirus. No, cloth masks work and are a necessity. No, cloth masks are useless The coronavirus can’t be transmitted more than six feet, but it can infect you if it’s on a surface. No, it is airborne and can be carried more than six feet, and the dangers of contacting it from a surface are negligible. Coffee is bad for you. No, coffee is good for you.

It should be noted that science is a process. Teams of scientists work full-time to elucidate every factoid, every insight, every detail about the natural world. The truth is out there, but it takes time to piece together the full story. Like early election returns, early pronouncements may turn out to be wrong. And scientists make mistakes. The process of science includes mechanisms for catching mistakes, but sometimes mistakes can slip through

When science meets money, though, these mechanisms can really break down. Take the example of partially hydrogenated oils. In the early 20th century, chemists reacted hydrogen with vegetable oils to make fats that stayed solid at room temperature. These fats had a longer shelf life and were cheaper to produce than lard, characteristics that promised higher profits to the food industry. Partially hydrogenated fats were sold to the public as healthy alternatives to animal fats and tropical oils because they were engineered to be slightly less saturated and had no cholesterol. This industrial product became a staple of the kitchen, synonymous with shortening, and the base ingredient of margarine.

Some eighty years later word got out that the story was not so simple. As every beginning chemistry student is taught, chemical reactions proceed both ways. The ingredients come together to form products, but the products also come back together to regenerate the initial ingredients, with the strength of each process determining the equilibrium level of ingredients and products. However, while the hydrogenation reaction will regenerate hydrogen in its reverse mode, a molecule as complex as a polyunsaturated fat will not necessarily return to its original form. The original molecule is in the cis form, characterized by a kink in a long-chain molecule, but the regenerated molecule tends to be in the straightened trans form, even though it will have the same atoms connected in the same order. Unless the hydrogenation process is pushed beyond partial to complete, there will always be molecules created in the trans form.

So-called trans fats are found in nature, but they are associated with bacteria. In the human body, industrial trans fats elicit an inflammation response. When they enter the bloodstream, the inflammation is manifested in the arteries, and the result is coronary disease. The engineered product that had been assumed for generations to be just another form of fat turned out to be deadly. Decades of studies linking saturated fat to heart disease had to be discounted because the effect of natural saturated fat could not be disentangled from the effect of trans fat.

While trans fat has no connection to trans genes, the example is instructive. The FDA has declared that all transgenic crops are no different from ordinary crops and thus do not require special regulation. Could they have unforeseen consequences? The answer is not known, because you can’t discover what you don’t test for. And while proponents of transgenic crops take pains to point out the absence of harmful effects in the billions of animals that have eaten transgenic feed, the process of insertion of genes is not vindicated by the lack of harm caused in one instance. It would be like a teenager driving at 100 miles an hour down a stretch of road and concluding afterward that because nothing bad happened, therefore nothing bad happens from driving 100 miles an hour. Maybe other transgenic crops will be thoroughly tested for safety, but the unsettling lapses in reasoning stand out.

Soybean disease researcher van Esse goes on to describe the Dunning-Kruger principle, the observation that the people who are least informed on a topic overrate their ability to act regarding it. The irony is that van Esse himself confesses knowing nothing about the social situation in Brazil but nevertheless feels confident to act there to solve what he identifies as a problem. Brazil is the home of some serious problems, prominent among them being the shocking rate of biodiversity loss, which is accompanied by displacement of indigenous peoples, along with a gap between the haves and the have-nots that is one of the worst in the world. Unfortunately, soy is not a neutral player, but rather a major contributor to these three problems.

Thanks to advances in agronomy, the Brazilian dictatorship in the 1970s was able to initiate colonization of the previously inhospitable center-west of the country by large-scale soy plantations. Auspicious market conditions pulled in a flood of foreign investment, promoting explosive growth of the soy industry, and also solidifying control of key infrastructure by multinational corporations. The most biodiverse savanna in the world quickly lost ground to soy monoculture.

The government has considered soy to be a boon to the Brazilian economy. It has certainly been a boon to the multinationals. However, the expansion of the soy frontier has dispossessed smallholders in its path, leading to a crisis of landlessness among the rural population. Because of the high level of mechanization in soy, rural workers were left with scant opportunities. Indigenous peoples find their lands under assault by the encroachment of agribusiness, among other threats.

Demand for soy has only accelerated since then. Governments of the left and right promote the industry. The soy frontier is penetrating the Amazon. Multiple crops per year are grown in the tropical zones that once supported savanna and rainforest. The turnaround time got so short that the combine drivers harvesting the soy could literally see the planters in their rearview mirror.

In 2001 Nature stepped in to spoil the party, in the form of Asian soybean rust. As any plant pathologist could have told the growers, continuous monocropping provides a breeding ground for diseases. Overuse of fungicides leads to pathogen resistance. The Brazilian government was forced to impose an annual soybean-free period, a sort of social distancing for soy plants, in order to help the fungicides to bend the curve of soybean rust disease downward. However, instead of getting the message that environmental destruction and social dislocation must stop and that soybean production must scale back, Dr. van Esse and the growers saw the challenge to genetically engineer a resistant soybean.

Not all opposition to genetic engineering in agriculture is based on gut feelings and a skepticism of science. There are scholars of the larger socio-economic context of agriculture who have valid critiques of genetic engineering that are based on a more comprehensive analysis. Take recombinant bovine growth hormone, rBST. The underlying problem of the US dairy industry is overproduction. The action that individual producers rationally take to increase their income is to produce more, but the overall effect of the sum of these individual decision is to depress prices, and individual growers then struggle to break even. If the market were the only force determining production levels, producers would go out of business en masse, and the supply of dairy products would show boom-and-bust cycles. Government must step in with price supports to insure an uninterrupted supply, as well as a living for the producers.

Enter rBST. The gene for bovine growth hormone is inserted into microbial cells, which are grown up in a vat. The resultant hormone is purified and packaged for injection into milk cows, causing them to increase their milk production. No transgenic organisms make it to the cows receiving the injection, and no trace of the transgene can ever get into the milk. The FDA has determined that there is no difference between the milk from cows receiving rBST versus those not receiving it, and they may very well be right. Nevertheless, many dairy companies tout their products as rBST-free. So what’s the issue?

Some animal welfare advocates express concern that the conversion of a cow’s body into a souped-up milk factory through the use of rBST could be detrimental to other areas of the cow’s well-being. From a whole-system perspective, increased production is the opposite of a solution in a saturated market. Nevertheless, students of plant pathology express amazement that anyone would be opposed to dairy products that have the FDA stamp of approval. Plant pathology professor Pam Ronald, whose lab takes credit for breeding a flood-tolerance gene from a farmer-developed rice variety into high-yielding rice by using modern genetic analysis tools, regularly skirts whole-system issues in her vociferous promotion of transgenic crops.

Which is not to say that transgenic crop researchers are maleficent. They truly believe that their technology can be used to help the poor. Unfortunately, if you have a hammer, everything looks like a nail. They see the statistics of blindness caused by vitamin A deficiency in the developing world, and they want to help in their own special way. While they delight in creating green-glowing bunnies – these really exist – the poster child for genetic engineering is golden rice.

Vitamin A, in the form of beta-carotene, is found in every green leaf on the planet, and can be highly concentrated in many orange-fleshed plant organs. If you eat your vegetables, you can’t help but get your vitamin A. Are all those children in the developing world getting away with not eating their vegetables? The late Professor George Wolf, a vitamin A expert at MIT, used to point out that a mother can crush leaves and feed them to her child to provide vitamin A. If vitamin A is so plentiful in the environment, how can deficiency be so widespread? Perhaps the example of the modernization of Indonesian agriculture is instructive.

Traditional Indonesian agriculture consisted of small rice paddies surrounded by earthen banks upon which vegetables were planted. The Green Revolution, a previous generation’s program for increasing crop production without considering the context (which was machinations by the powerful to marginalize small growers, not lack of productivity), created high-yielding rice to replace the traditional varieties. The Indonesian dictator overcame technology skepticism by torching the fields of peasants who refused to convert their small paddies to extensive monocrops of Green Revolution rice. The banks of vegetables were gone, and the era of easy access to vegetables was over. While other countries have other stories, there is a general trend that Western modernization by top-down development schemes focusing on getting calories into the poor has caused the demise of vegetable cuisine in the developing world.

Besides vitamin A, vegetables are the source of many other important factors, such as folic acid, potassium, fiber, anti-oxidants, anti-cancer compounds, and more. Transgenic crop researchers saw the vitamin A deficiency, figured out how to make rice plants accumulate beta-carotene in the starch of the grains, and began a campaign to get golden rice into the mouths of poor children. Never mind that a high-carb diet with an accompanying dose of vitamin A will still leave the poor vulnerable to the kind of inflammatory diseases that plague the West. If you declare your opposition to golden rice, you open yourself to accusations that you don’t care about the poor.

The persecution gets worse. When a group of dissident UC Berkeley scientists discussed opposing the showing of a film promoting GMO agriculture on campus, they were subjected to a smear campaign. A middle school school teacher in Maryland who is also an oddly well-connected pro-GMO crusader summoned their email chain through a Freedom of Information Act request. He then spread false accusations of conflicts of interest against them around the internet, a charge that would be more appropriate against researchers receiving funding from large corporations. Ever wonder why I blog incognito?

Agricultural research grants usually require a public outreach component. Soybean rust researcher Van Esse wonders why plant pathologists haven’t done a better job convincing the public of the correctness of their solutions. Rather than better commercials, what the grants should require is consultation with activist groups, with the opinions of dissident researchers actively sought out. Ideally, considerations of profit should be excluded from discussions of the benefits and drawbacks of a GMO project. GMO researchers should approach outreach with the realization that they are not the most informed authorities about agricultural issues and thus are not as qualified to act as they imagine they are. And regulatory agencies should apply the precautionary principle, assuming that new technologies are risky until proven safe, rather than giving the green light and finding out in retrospect that a technology is harmful.

And when you hear money talk, take a listen to your gut. Then seek out the rest of the story.

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smaller fleas

It was during smalltalk over a shared breakfast table on Amtrak that the man across from me began excoriating powdery mildew. He was a Colorado pot grower. His greenhouse operation held hundreds of plants, and the air circulating between his and the adjoining pot greenhouses was spreading the spores of the leaf parasitic fungus that had somehow gained a foothold inside. The greenhouse conditions provided an ideal environment for germination and growth of powdery mildew, and the high density of plants insured an endless supply of favorable landing spots for the dust-like particles that can each start a new colony. Despite the lore, pot plants are not indestructible, but rather serve as hosts to many pests and diseases, with powdery mildew being a leading factor threatening pot growers’ investment. Powdery mildew doesn’t kill a plant outright, but it weakens the plant and lowers the harvest quality.

There are about a hundred species of powdery mildew that make up this family of fungi. A powdery mildew’s thread-like growths cover the surface of a leaf and send root-like structures into the cells to feed. Its upright chains of spores give the impression of powder on the leaf. Powdery mildew is known as an “obligate biotroph”, meaning it can only survive on living host tissue. A key requirement of this infection type is that the fungus must come pre-programmed to neither kill the parasitized plant cell nor awaken the cell’s defense mechanisms, a balancing act accomplished through a tightly choreographed sequence of interactions with the cell’s machinery.

A reality of the plant world, though, is that distantly related plant species have distinct cellular machinery, meaning that a powdery mildew species that is not correctly pre-programmed, that is to say, coevolved with the plant it arrives on, will trip up and not be able to infect. Thus the powdery mildew on the sowthistle next door will not spread to your pumpkins, and the powdery mildew that emerges on the rosebush at the end of the row of grapevines and signals the grower to spray sulfur on the vines is not the species that actually infects the vines.

What the powdery mildew species have in common is similar germination requirements. The reason for this is that the spores carry their own moisture, allowing them to germinate without the liquid water that most fungal spores require. In fact, liquid water inhibits powdery mildew spore germination and can even cause the spores to burst. The spores do need a certain amount of humidity to germinate, but it can be as low as 50% relative humidity, and germination works better within a mild temperature range and at lower light levels. Outdoors there are certain times of year when powdery mildew blooms, but greenhouses are always ideal incubators waiting for spores to arrive.

For control of powdery mildew on grapevines, great quantities of sulfur and fungicides are sprayed, the most for any pathogen. However, since weed is newly legalized and gets smoked, growers don’t have an arsenal of chemicals registered for use on it. Cannabis pathologist Zamir Punja from British Columbia has found a few treatments to be effective, including Regalia, which is an extract of giant knotweed, Milstop, which is similar to baking soda but without the sodium, and germicidal ultraviolet light for a few seconds a day. There are some biocontrols that show promise as well. These mostly produce inhibitory chemicals or destructive enzymes against the fungus, or prime the plant to fight off infection, but a recent study from Hungary led by Márk Németh working in the lab of Levente Kiss shows the potential of a biocontrol agent that acts like a creature from science fiction.

In John Carpenter’s 1982 re-visioning of the sci fi classic The Thing, there is not monster played by a man in a suit as in the original, but instead a shape-shifting menace that lives inside its victims, compelling them to act in ways that benefit this alien life form while they retain their own personality. The most riveting scene is where the Kurt Russell character uses a flamethrower to kill a crew member carrying the parasite, which had revealed itself when it had burst out of his chest to engulf the arms of a comrade. The carrier is lying on a table as the flames sear his body, but his head hanging over the edge is out of direct exposure. To the horror of the crew and the audience alike, the head grows a stalk to lower itself to the ground then sprouts legs and tries to slink away. The film proceeds with an air of paranoia as crew members try to figure out who else may be harboring the monster.

The Thing was inspired by the atmosphere of fear and suspicion associated with the cold war, as were many if not all classic sci fi movies, but it could have been inspired by Ampelomyces. This fungus lives inside the tiny threads that make up the powdery mildew. It doesn’t kill the host fungus at first, but grows inside it, finally hijacking its reproductive structures to make more Ampelomyces. The tiny powdery mildew spores become filled with the even tinier spores of the hyperparasite, so-called because it is a parasite of a parasite.

The basic life history of Ampelomyces has been known since the nineteenth century, but Németh et al. have done the definitive study by engineering this fungus to glow green under blue light, allowing them to see its diminutive threads inside its host. They accomplished this using a gene from a jellyfish and a bacterium from a plant gall. The jellyfish is the bioluminescent crystal jelly of Puget Sound, which has a gene for producing green fluorescent protein. The bacterium is the pathogen responsible crown gall in plants, and it alters the growth of its host by inserting a plant tumor gene into the host’s DNA. The scientists replaced the bacterium’s tumor gene with the green fluorescent protein gene, added the bacterium to the fungus culture, and created the green-glowing fungus they were seeking.

One of the key questions that could be answered with an easily seen fungus was, what happens to it outside its host? It turns out that it can survive on a leaf surface for weeks after germination before any host comes along. Considering how utterly tiny the hyperparasite is, and the fact that it is not eating during that time, this is quite a feat. This feature is advantageous for harnessing it as a biocontrol agent, as a grower would not have to wait until a plant is suffering from a powdery mildew infestation to apply Ampelomyces spores. With some appropriate greenhouse trials this might become an additional tool in the pot grower’s toolbox.

Németh et al. also confirmed previous work showing that, unlike powdery mildew, Ampelomyces is not specific to a single host species, but is able grow within many different species of powdery mildew. This feature might make it amenable to conservation biocontrol, where the biocontrol agent is not raised commercially and sprayed onto the crop, but rather the agroecosystem is managed in such a way that hosts are always available for the biocontrol agent to survive on site. Perhaps a grower could leave sowthistles growing around the perimeter of the system to protect the pumpkins. Perhaps the rosebushes at the ends of the grapevine rows could serve not as early warnings for spray timing, but as reservoirs of biocontrol fungus. Further study is required.

And so Jonathan Swift’s observation rings true: “…a Flea/ Hath smaller Fleas that on him prey,/ And these have smaller yet to bite ’em,/ And so proceed ad infinitum…”. Powdery mildew will always be around, but for Ampelomyces that’s a good thing.

Your turn

If you found value in what you have read on this site, feel free to return the favor with a small financial contribution. As of January 2023 I have no other source of income. Clicking on the picture will take you to PayPal. If you are on the single-article page, you can also scroll down to join the conversation.