By Derek Yang, edited by Reyhan O.
Dallas, TX
The global temperature continues to rise at an alarming rate as carbon dioxide levels increase. This shift causes a myriad of disruptions in weather patterns, including an increase in precipitation, droughts, heat waves, dust storms, and tornadoes. These, in turn, change patterns in fungal disease distributions and severity, which have considerable implications in agriculture.
For example, fungal spores rely on wind for dispersion, and more dust storms and tornadoes (in addition to more wind from the uneven heating of Earth’s surface) can aid in this dissemination. Second, because fungi rely on moisture to reproduce and infect, an increase in precipitation will translate to a physical increase in fungal mass (and by extent, pathogenic material). Finally, a greater global temperature can lead to fungi adapting to higher temperatures, allowing them to travel farther north and infect agricultural regions who have not learnt to deal with such new diseases.
For example, farmers in Ireland and England have reported significant cases of wheat stem rust infections, which have historically only occurred in South-European regions. Significant losses in wheat, which consists of one of the five of the world’s most nutritionally and culturally important crops—the others being rice, maize, soya beans, and potatoes—would equate to a loss of 2000 categories for almost 600 million people.
According to a 2023 ScienceDaily article by researchers at the University of Exeter, farmers lose from 10% to 23% of their annual harvests due to fungal infections. Fungal infections represent a significant challenge to farmers, as many spores can overwinter and remain in the soil for up to 40 years without causing any symptoms. Also, traditional solutions such as crop rotation, crop destruction, and the use of hybrids have proven ineffective or too expensive. For instance, using antifungals or other chemicals have resulted in resistance in fungal strains and have detrimental impacts on the environment and ecosystem.
However, given recent developments in biotechnology accessibility, scientists and researchers have begun turning toward the use of endophytes to treat crop diseases. An endophyte refers to a fungal or bacterial microorganism that lives within a plant’s endosphere. The endophyte is very specific to its host plant; indeed, an endophyte that proves beneficial to maize may be parasitic in sorghum. While much research is still required to ascertain the mutualistic relationships between the endophyte and the plant, scientists have agreed that endophytes can help protect the plant from fungal infections by secreting secondary metabolites known as mycotoxins (ex. siderophores that deplete the fungus of iron), by competing with the fungus for space and nutrients, and by altering the plant’s genetic code to induce systemic resistance. Other benefits of endophytic applications include tolerance of environmental stress, promotion of plant growth, phytoremediation, bioremediation, and production of medicines.
Endophytic research has only been mostly limited to in vitro conditions: scientists have suggested that future research try studying endophytic biocontrol under more realistic field conditions, where abiotic and biotic factors are studied in tandem. Perhaps some limitations to true field applications include endophytes’ specificity of growing conditions and difficulty in large-scale application. Endophytes rely on a specific set of growing conditions (soil pH, temperature, soil moisture, humidity, altitude, salinity, soil nutrient content) to thrive and confer their advantages to crops. While researchers are still experimenting to discover the most effective method of endophytic application in the field, there have been a few suggestions: farmers could apply the endophytes directly to crops via sprays, seeds, or root inoculation.
One significant limitation to endophytes is that their efficacy in controlling fungal diseases can vary significantly within the same species or even the same strain, as endophytes are very sensitive to differences in climatic conditions. Also, only a very limited number of endophytes for crops have been identified, and discovery can be painstakingly slow and excruciatingly slow. Finally, many researchers and even consumers are concerned with the effects of introducing an invasive bacteria into new environments.
As fungal diseases continue to worsen and spread due to climate change, the incidence and severity of fungal infections in crops continue to worsen as well. Thankfully, even though traditional solutions to fungal infections have proven ineffective, endophytes could be the next big solution. With further field research into methods of application and effectiveness in planta, endophytes could help mitigate fungal infection issues.
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