RESUMO
Tomato yellow leaf curl disease (TYLCD) causes severe damage to tomato crops worldwide. The deployment of host-plant resistance is the most desirable mean to control this disease. However, some concerns exist because it may place a selection pressure on the virus. Field and experimental data are provided which suggest that the use of TYLCD resistance in tomato crops might have contributed to the emergence of tomato yellow leaf curl virus in the TYLCD-associated virus population, a virus species that fits better in the resistant genotypes. Emergence of recombinant variants was observed during mixed infections of TYLCD-associated viruses in Ty-1 resistant plants, as already observed for susceptible tomatoes. Therefore, selection may be occurring for virus variants with novel genome combination to infect the resistant genotypes with this resistance gene.
