Plant viruses pose a serious and ongoing threat to global agriculture in tropical to temperate regions. Among the most damaging are begomoviruses, a group of DNA viruses spread by whiteflies that infect many important food crops, including eggplant, tomato, pepper, cucurbit, cassava, and cotton. Infected plants often develop yellowing and curling leaves, stunted growth, and reduced yields, leading to significant economic losses for farmers.
In a new study published on December 27, 2025, in Theoretical and Applied Genetics , Volume 139, Article Number 20, researchers identified a gene in eggplant (Solanum melongena) that provides resistance to begomovirus infection. The work reveals a previously unknown defense mechanism and highlights clear biological differences between virus-resistant and virus-susceptible plants.
The study was led by Associate Professor Sota Koeda from the Graduate School of Agriculture, Kindai University, along with Nadya Syafira Pohan (Ph.D. candidate) from Kindai University. According to Dr. Koeda, "This study is the first to clone a begomovirus resistance gene in eggplant. We also demonstrated, for the first time in plants, that an exonuclease is associated with begomovirus resistance."
The researchers focused on a gene known as Eggplant yellow leaf curl disease virus resistance 1 (Ey-1). This gene encodes a DEDDh exonuclease, an enzyme that can degrade nucleic acids (DNA and/or RNA). In simple terms, the enzyme appears to damage the virus's genetic material, limiting its ability to multiply inside plant cells. To understand how Ey-1 works, the team compared eggplant lines that were resistant to begomoviruses with those that were susceptible. When exposed to the virus, resistant plants remained largely healthy, showing normal leaf shape and growth. In contrast, susceptible plants developed severe leaf curling and other disease symptoms, typical signs of begomovirus infection.
The difference was not just visible but measurable. The researchers found that virus-resistant plants accumulated far lower levels of viral DNA than susceptible plants. This result confirmed that Ey-1 does not merely reduce symptoms but actively limits viral accumulation inside the plant. This distinction between resistant and susceptible plants is especially important for agriculture. Begomoviruses are difficult to control because they are transmitted by whiteflies, which are hard to manage and increasingly resistant to chemical insecticides. As a result, farmers often rely on repeated pesticide applications, which can harm the environment and pose risks to human health.
"Our findings will contribute to the eco-friendly control of begomovirus-caused diseases and help ensure food security," says Dr. Koeda.
The study's implications extend beyond eggplant. By understanding how Ey-1 confers resistance, plant breeders may be able to develop new crop varieties that are naturally protected against begomoviruses. Such crops would reduce the need for insecticides by targeting the virus itself rather than its insect vector. Dr. Koeda emphasizes the long-term benefits of this approach: "This knowledge can be applied to breed virus-resistant crops, which would reduce the amount of insecticide used to control whiteflies. This would benefit not only the natural environment but also the health of producers."
The motivation behind the research is rooted in real-world experience. Dr. Koeda has visited vegetable-growing regions in Japan and overseas, particularly in tropical and subtropical areas where begomovirus outbreaks can devastate crop production. These observations highlight the urgent need for durable, genetics-based solutions.
In conclusion, by clearly linking a single gene to measurable differences between virus-resistant and virus-susceptible plants, the study provides a strong foundation for future breeding efforts. The discovery of Ey-1 represents a meaningful step toward more resilient crops and safer, more sustainable food production systems.
