The next big thing for RNA?Repair moldy food

all Fungus outside, Botrytis cinerea It is something that keeps farmers awake at night. The hairy fungus has a greedy appetite. It chews hundreds of plants happily—although soft fruits like grapes are its favorite—it covers everything it enjoys with a velvety layer of mold.If you have kept a bucket of strawberries in the refrigerator for too long, and then come back and find that they look a little gray-green, it is likely to be one of the ever-present spores Botrytis Floating in the air decided to let it stay in your dessert forever.

Deteriorating desserts are a pain, of course, but for the food industry Botrytis A major question was raised.A single species of fungus is at least right $10 billion in losses The annual crops. Some estimates this figure is as high as 100 billion U.S. dollars.Too much trouble, a survey of plant pathologists listed it as Second most important Plant fungal pathogens, in what can only be described as their industry equivalent time The magazine’s “Most Influential People” list. (Go to the highest point Magnaporthe grisea: A fungus that destroys rice fields all over the world. )

“This is a big problem,” said Mark Singleton, head of plant and animal health at GreenLight Biosciences, a Massachusetts-based biotechnology startup that is committed to developing a new generation of sprays to resist Botrytis And other pests that plague farmers. The shortcomings of existing fungicides and insecticides are well known: spray residues can accumulate in the environment and damage non-target organisms, and excessive use can cause pests and weeds to become resistant. Singleton is researching ways to solve these problems. His starting point is RNA: a molecule similar to DNA that is one of the basic components of life.

The new generation of pesticides is based on a cellular technique that dates back more than 1 billion years, at least in Last common ancestor Animals, plants, fungi and protists. At some point—we are not sure when—cells have evolved the ability to cut and destroy genetic material from invading pathogens (such as viruses). When a cell detects the presence of double-stranded RNA (dsRNA)—a piece of genetic code that the virus uses to replicate itself—it breaks this dsRNA into smaller pieces. These dsRNA blocks are like tiny wanted posters. The molecules in the cell pick them up and use them to find any matching messenger RNA (mRNA) fragments—the molecules that the cell uses to convert genetic instructions into proteins. If the molecular baddies are chopped up before they start to be made into proteins, the cells will successfully invade.

The discovery of this process-called RNA interference (RNAi)-gave two scientists the 2006 Nobel Prize in Physiology or MedicineIt also sparked a race to develop new tools based on it. Scientists soon realized that if you can introduce dsRNA into a nasty pathogen—such as a particularly irritating fungus—you can instruct the pathogen’s cell to destroy its own mRNA and prevent it from making key proteins. In essence, they can turn off genes in pathogens at will. “We just went in and looked at the gene and protein orchestra there, and we were muting the violin. That’s all we did,” said Michael Helmstetter, chairman of RNAissance Ag, another company trying to push RNA crop sprays to Startups in the market.

Some RNA sprays are already in progress. RNAissance Ag is developing a spray for the diamondback moth, which has an insatiable appetite for cabbage and Has evolved some resistance To common pesticides. GreenLight Biosciences has an RNA spray for the Colorado potato beetle, which is currently being evaluated by the Environmental Protection Agency. The company expects to make a decision on the spray by mid-2022.It is also working on a spray for Botrytis cinerea, And a blow Varroa, A widespread pest that infects bees. After preliminary laboratory tests, GreenLight is now field testing its Botrytis spray on grapes in California and strawberries in Italy. Singleton said that they are looking for how long the spray will attach to plants and how it compares to chemical fungicides.

Compared with current chemical pesticide toolboxes, RNA crop sprays may have some major advantages. Microbes will decompose the RNA in the soil within a few days, thereby alleviating the problem of environmental accumulation. And because RNA sprays target the genes of a particular species, there is a much lower chance (at least in theory) that other organisms will be involved in the crossfire. Clauvis NT Taning, a postdoctoral researcher researching RNAi insecticides at the University of Ghent in Belgium, said that even two very similar species have enough genetic differences that it is possible to create RNA sprays for one insect and let the other. The bugs exist alone.

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