News Tip: Citrus tristeza virus carries extra genes that help it infect more plants
GAINESVILLE, Fla. — New research helps explain how one of the most troublesome citrus viruses can infect multiple plant species and varieties: It carries extra genes that help provide entry to a wider range of hosts.
The findings were announced today in the journal Proceedings of the National Academy of Sciences. University of Florida plant pathology expert Bill Dawson is part of the research team that conducted the study.
Transmitted by aphids, citrus tristeza virus is a significant problem for Florida’s $9 billion citrus industry. It causes gradual decline and death in citrus trees, primarily those that use sour orange rootstock. In the citrus industry, it’s common practice to grow trees by grafting the above-ground portion of one variety to rootstock from a different variety that’s well adapted to soils and growing conditions in the area.The scientists focused on three citrus tristeza virus genes associated with infection. First, they produced modified viruses that lacked one, two or all three of the genes. Then, they took the modified viruses and tried to infect plants susceptible to the wild type of citrus tristeza virus. Plants including grapefruit, lemon and sour orange became infected by some of the modified viruses.
These results suggest that citrus tristeza virus incorporated new genes into its genome at some point during the virus’ evolution. The study also demonstrates that interactions between viruses and their host plants can be extremely complex.