The Spread of Tomato Yellow Leaf Curl Virus from the Middle East to the World

Abstract

The ongoing global spread of Tomato yellow leaf curl virus (TYLCV; Genus Begomovirus, Family Geminiviridae) represents a serious looming threat to tomato production in all temperate parts of the world. Whereas determining where and when TYLCV movements have occurred could help curtail its spread and prevent future movements of related viruses, determining the consequences of past TYLCV movements could reveal the ecological and economic risks associated with similar viral invasions. Towards this end we applied Bayesian phylogeographic inference and recombination analyses to available TYLCV sequences (including those of 15 new Iranian full TYLCV genomes) and reconstructed a plausible history of TYLCV's diversification and movements throughout the world. In agreement with historical accounts, our results suggest that the first TYLCVs most probably arose somewhere in the Middle East between the 1930s and 1950s (with 95% highest probability density intervals 1905–1972) and that the global spread of TYLCV only began in the 1980s after the evolution of the TYLCV-Mld and -IL strains. Despite the global distribution of TYLCV we found no convincing evidence anywhere other than the Middle East and the Western Mediterranean of epidemiologically relevant TYLCV variants arising through recombination. Although the region around Iran is both the center of present day TYLCV diversity and the site of the most intensive ongoing TYLCV evolution, the evidence indicates that the region is epidemiologically isolated, which suggests that novel TYLCV variants found there are probably not direct global threats. We instead identify the Mediterranean basin as the main launch-pad of global TYLCV movements.

Vector development and vitellogenin determine the transovarial transmission of begomoviruses

“…TYLCV, one of the world's most devastating pathogens of tomato, is considered to have spread from the Middle East or the Eastern Mediterranean to the world since the 1980s, and the dissemination process is probably still ongoing (47,48). The global invasion of MEAM1 and MED whitefly together with the movement of infected plant material are believed to be the two main factors that are attributed to the rapid spread of TYLCV worldwide (49,50).…”

Genetic diversity, host range, and distribution of tomato yellow leaf curl virus in Iran

“…It is also possible that TYLCV was introduced to the Northern provinces by the exchanges of TYLCV-infected seedlings, plant materials or by viruliferous whiteflies from infected countries in the Middle East region to the southern regions of Iran (Navas-Castillo et al, 1999;Kim et al, 2011). It has been recently elucidated that Mediterranean basin and Middle East are the main launch-pad of global TYLCV movements (Lefeuvre et al, 2010). Results also showed that the occurrence of TYLCV in central regions of the country, pointing to the distribution of this virus through the country, which may expand to the northern regions, where numerous kinds of host are available for the virus as the potential infection sources.…”

In silico analysis of gene content in tomato genomic regions mapped to the Ty-2 resistance gene

“…Tomato yellow leaf curl virus (TYLCV) has severely affected the growth of tomato crops and world tomato production in recent years, and has been reported on a global scale (Accotto et al, 2000(Accotto et al, , 2003Delatte et al, 2005;Wu et al, 2006;Lefeuvre et al, 2010;Melzer et al, 2010). Currently, the disease is primarily managed by spraying pesticides to control the virus vector whitefly.…”