Sun. Nov 28th, 2021


Of all There’s fungus, Botrytis cinerea Keeps farmers awake at night. The Scoozy fungus has an indifferent appetite. It will happily shake through hundreds of plant species – although soft fruits like grapes are its favorite – it covers everything it eats with a velvet layer of mold. If you’ve ever left a tub of strawberries a little too long in the refrigerator and come back to see that they look a kind of gray-green, there’s a good chance that the strawberries have an ever-present spore. Botritis Floating in the air has decided to make your dessert home forever.

A spoiled dessert is a pain, sure, but for the food industry Botritis Causing a big problem. This single species of fungus is responsible for at least that The damage was $ 10 billion For harvesting every year. Some estimate as high as $ 100 billion. It is so troublesome that a survey of plant pathologists ranked it The second most important Plant fungi are pathogens, which can only be described as their industrial equivalents Time Magazine’s “Most Influential People” list. (Went to the top Magnaporthe oryzae: A fungus that destroys rice fields around the world.)

“It’s the biggest,” said Mark Singleton, head of plant and animal health at Massachusetts-based biotech startup Greenlight Biosciences. Botritis And other pests that disturb farmers. Harmful aspects of existing fungicides and pesticides are well known: Residues of sprays can accumulate in the environment and harm non-target organisms, while their excessive use can lead to the development of pest and weed resistance. Singleton is working on these issues. And its starting point is RNA: a molecule similar to DNA that is one of the most basic building blocks of life.

This new generation of pesticides is based on a cellular technique that is more than a billion years old, at least as far as The last common ancestor Animals, plants, fungi and protists. At some point — we are not sure exactly when those cells developed the ability to cut and destroy genetic material from invading pathogens like viruses. When a cell detects the presence of double-stranded RNA (dsRNA) – an extended genetic code that viruses use to replicate themselves – it hacks this dsRNA into smaller pieces. These pieces of dsRNA are like small wanted posters. Cell molecules pick them up and use messenger RNA (mRNA) to detect any combined proliferation – molecules cells use to convert genetic instructions into proteins. If the molecular bad ones are cut off before they start making proteins, the cell will start a successful attack.

The discovery of this process – called RNA interference (RNAi) – was made by two scientists in 2006. Nobel Prize in Physiology or Medicine. It has also spread a race to develop new tools based on it. Scientists soon realized that if you could introduce dsRNA into a disruptive pathogen – a particularly annoying fungus, for example – you could instruct the cells of that pathogen to destroy its own mRNA and prevent it from making important proteins. In short, they can turn genes into pathogens at will. “We’re just going there and watching the orchestra of genes and proteins there and we’re silencing the violin. That’s all we’re doing, “said Michael Helmstater, chair of RNAissance Ag, another startup that seeks to bring RNA crop spray to market.

A handful of RNA sprays are already working. RNAissance Ag is working on a spray that targets the diamondback moth, which has an insatiable appetite for cabbage and Some resistance has already developed To common pesticides. Greenlight Biosciences has an RNA spray targeting the Colorado potato beetle that is currently being evaluated by the Environmental Protection Agency. The company expects to make a decision about this spray by mid-2022. It also works on a spray Botrytis, As well as one that combats Varroa mite, A widespread insect that infects honey bees. After initial laboratory testing, Greenlight is now testing its botrytis spray on grapes in California and strawberries in Italy. Singleton said they are trying to find out how long the spray sticks to the plant and how it compares to chemical fungicides.

RNA crop sprays may have some major advantages over current toolboxes of chemical-based pesticides. The germs break down RNA in the soil within a few days, which reduces the problem of environmental formation. And since RNA sprays will target specific genes for individual species, there – at least theoretically – other organisms are much less likely to be caught in crossfire. Even two very similar species have enough genetic differences that it is possible to spray RNA that targets one bug and leaves the other alone, says Clavis NT Tanning, a postdoctoral researcher who studies RNAI pesticides at Ghent University in Belgium.



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