Nanoscale nutrients can protect plants from fungal diseases
Nanoscale nutrients can protect plants from fungal diseases
Tuning the chemistries of nanomaterials changes the plants’ response levels to fungal pathogens
The likelihood is that the majority, if not all, of the produce in your kitchen is at risk from fungi-related diseases. The threat to global food staples including rice, wheat, potatoes, and maize is significant (SN: 9/22/05). Additionally, harmful fungi are threatening our coffee, sugarcane, bananas, and other crucial crops for the economy. A third of all harvests are lost to fungal infections every year, which is a serious danger to the world’s food security.
Farmers use poisonous chemicals to fumigate the soil in an effort to limit the spread of fungal diseases, sparing neither the land’s natural resources nor the beneficial bacteria that abound there. Or they spray fungicides on the plants. However, using fungicides only works temporarily, or at least until harmful fungus develop a tolerance to these synthetic drugs.
The concept of empowering plants with the means to defend themselves is now gaining traction. A group at the Connecticut Agricultural Experiment Station in New Haven, led by environmental toxicologist Jason White, is supplementing crops with nutrients packaged into nanosized packets that increase plants’ inherent protection against pathogenic fungi more effectively than conventional plant feeding. According to an article in the April Plant Disease, over the past several years, the researchers have developed a variety of nanonutrient mixtures that increase the fungal resistance of soybeans, tomatoes, watermelons, and, most recently, eggplants.
Leanne Gilbertson, an environmental engineer at the University of Pittsburgh who was not involved in the research, says the idea “tackles the challenge at the genesis rather than attempting to put a Band-Aid on the [problem]”. White’s plan gives plants the nutrition they require to start producing enzymes that will protect them from pathogenic attack. The tactic avoids any chance for malignant fungi to develop resistance because no synthetic chemicals are used, according to her.
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The researchers’ prior discovery that nanoparticles transported up from the roots of maize can loop back down from the leaves served as inspiration for their nanomaterials strategy. One maize plant’s root fibers were divided in half and submerged in pure water and a formulation of copper nanoparticles by the researchers. The copper was detected in the roots that had been submerged in water, indicating a roots-to-shoots-to-roots circular pathway, according to a 2012 Environmental Science & Technology study by White and his colleagues. This result suggested that even when the roots were the intended destination, nanoparticles may still be delivered straight to the leaves.
By using the leaves as a point of entry, the perennial issue of the ineffectiveness of delivering dissolved nutrients through the soil is avoided. Chemicals can evaporate into the air, decompose in the soil, or leak away. Only approximately 20% of the nutrients that are watered to a plant actually go to the desired locations. We can actually more efficiently deliver [nutrients] where we want them and where the plant needs them by employing the nanoscale form, according to White.
White and colleagues tested this method in tomatoes and eggplants to see if it could give nutrients especially required in defense against adversarial fungi. Young plants’ leaves and shoots were treated with metallic nanoparticles before being infected with pathogenic fungi. In comparison to plants supplied readily dissolved nutrients, the plants treated with nanoparticles had higher produce yields and higher levels of nutritional metals in the roots, the study reported in Environmental Science: Nano in 2016.
The researchers discovered that the fungi weren’t being harmed by the nanoparticles because they continued to grow even in the absence of the host plant. Instead, the antifungal effects of the nanoparticles come from giving plants the nutrition they need to create an effective defense when necessary. This is analogous to giving people nutritional supplements.
According to Fabienne Schwab, an environmental chemist who was not involved in the research, nanonutrients are more potent than conventional fertilizers because of the sweet spot in their sizes, which controls how quickly they dissolve. Nanonutrients are thousands of times smaller than a human hair’s diameter and thousands of times larger than nutrient salts that can be readily dissolved. They dissolve more quickly than a larger chunk of the same nutrient due to their large, exposed surface. However, because nanonutrients are so large, the nutrients can be released gradually over a period of weeks rather than instantly dissolving. In contrast, plants experience a brief sugar surge from readily absorbed nutrients.
According to Schwab of the Adolphe Merkle Institute in Fribourg, Switzerland, “you can tune the solubility pretty much the way you wish when you use [nutrients] at the nanoscale.”
The form, composition, and surface chemistries can also be changed to trigger different levels of a plant’s reactions, so it’s not simply the size that can be tweaked. For instance, White and his colleagues discovered that spherical copper nanoparticles were less effective than nanometer-thin copper oxide sheets at protecting soybeans from Fusarium virguliforme infection. The faster release of charged copper atoms and the nanosheets’ more powerful adsorption to leaf surfaces were the secrets to their efficiency. The researchers published a study on the effects of copper nanoparticles on soybean bulk and photosynthetic rates in Nature Nanotechnology in 2020.
It’s a highly promising technology, but there are other things to think about before it’s put into practice, says Schwab. Agricultural nanotechnology needs to follow environmental and safety requirements, as well as – possibly much more difficult to do — get beyond consumer skepticism, if it is to be widely used. White and his associates have not yet discovered any leftover nanonutrients in their produce that would end up on consumers’ plates. Other effects, however, such the permanence of the nanomaterials in the environment and the dangers they represent to human handlers, are still not well understood.
When you discuss food with nanotechnology, “people generally get nervous,” claims White. He claims that his crew is not utilizing any exotic elements, whose effects on health are still completely unknown. Instead, “we’re employing nutrients that plants absolutely require and deplete rapidly.”
White claims to have consumed the watermelons, tomatoes, and eggplants he has raised for his study. Perhaps the best assurance for consumers is to see a toxicologist really using the product of his effort.