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Researchers at the University of Johannesburg (UJ) have delved into the molecular genetics of tomato plants to understand how they can fend off the devastating tomato curly stunt virus (ToCSV). This research has recently been shared in the Frontiers in Plant Science journal.
Historically, the Ty-1 gene has been identified to give tomatoes resistance against the widely known tomato yellow leaf curl virus (TYLCV). The UJ team has now expanded this investigation to examine the tomato's response to ToCSV when the Ty-1 gene is present. Their studies have established a relationship between tolerance to the ToCSV virus, viral DNA methylation (a plant defense strategy), and the Ty-1 gene's activity.
In their quest for a deeper understanding, the researchers employed lab methods such as bisulfite conversion, PCR amplification, and whole genome virus sequencing.
Tomato crops, being the third-largest vegetable yield globally, are under persistent threat from various pathogens. The ToCSV is a relatively recent entrant in this list, emerging in South Africa around three decades ago. Transmitted by whiteflies, this virus has proven its potential to wipe out entire tomato crops, with occurrences documented not only in South Africa but also in neighboring Mozambique.
Dr. Farhahna Allie, the study's lead author and a researcher at UJ's Department of Biochemistry, points out the genetic resemblance between ToCSV and the older TYLCV. Yet, the mechanisms tomatoes might employ against the former remain largely under-researched.
Drawing an analogy, Dr. Gerrit Koorsen, the study’s co-author, likens the virus to a Trojan Horse. Geminiviruses, including ToCSV, are reliant on the host plant for replication. They trick the plant into replicating the viral DNA, thereby propagating the infection.
The researchers then narrowed their study to two types of tomatoes: one that is vulnerable to ToCSV and another with a degree of tolerance. This comparative study was pivotal in understanding how plants can fend off newer viruses like ToCSV and potentially lead to the breeding of resilient crops.
Findings suggest that the tolerant tomato variety can activate the Ty-1 resistance gene more efficiently, indicating a possible line of defense against the ToCSV. A fascinating aspect of the research involves understanding DNA methylation, a process where plants seem to "tag" specific areas on the viral DNA, inhibiting the virus from reproducing within the plant cell.
Dr. Allie is eager to continue research into the various defensive mechanisms tomatoes might have against viruses, while Dr. Koorsen believes there's vast potential in leveraging emerging computational techniques, including Machine Learning (ML) and advanced AI, to further their research.