Showing papers by "Rafael Fernández-Muñoz published in 2010"

Resistance to Tomato chlorosis virus in wild tomato species that impair virus accumulation and disease symptom expression.

Abstract: Tomato chlorosis virus (ToCV) (genus Crinivirus, family Closteroviridae) is an emerging threat to tomato crops worldwide Although symptoms on fruits are not obvious, yield losses occur through decreased fruit size and number Control of ToCV epidemics is difficult because the virus is transmitted by several whitefly vector species and its relatively wide host range facilitates establishment in local wild reservoirs Therefore, breeding for ToCV resistance offers the best control alternative However, no sources for resistance are available thus far Here, a screen of tomatoes and wild species relatives was performed in search of ToCV resistance Two sources of resistance to ToCV were identified in this work, lines '802-11-1' and '821-13-1', each derived by two self-pollinations from ToCV asymptomatic plants of the population 'IAC CN RT' (derived from an interspecific hybrid Solanum lycopersicum x S peruvianum accession LA0444) and accession LA1028 (S chmielewskii), respectively The resistance was expressed by impairing virus accumulation and disease symptom expression, both under natural infection and after challenging with ToCV in controlled inoculations Genetic control of resistance to ToCV infection in '821-13-1' was conferred by a major locus with mainly additive effects but also partial dominance for higher susceptibility Also, an additive x dominance epistatic interaction with at least one additional gene was evident

Multiple Resistance to Meloidogyne spp. and to Bipartite and Monopartite Begomovirus spp. in Wild Solanum (Lycopersicon) Accessions.

Abstract: The Ty-1 locus confers tolerance to monopartite and bipartite Begomovirus spp. (genus Begomovirus, family Geminiviridae) and this phenotype is improved in homozygous tomato lines. However, the gene Mi (Meloidogyne spp. resistance) is in repulsion phase linkage with Ty-1, which hampers the large-scale development of multiresistant inbred lines. Seventy-one Solanum (section Lycopersicon) accessions were whitefly inoculated with the bipartite Begomovirus sp. Tomato rugose mosaic virus (ToRMV) and simultaneously infested with a mixture of Meloidogyne incognita and M. javanica under greenhouse conditions in Brazil. Accessions were then transplanted into a nematode-infested field with natural ToRMV infection. A severity index was used to evaluate ToRMV reaction. Nematode evaluation was done by counting the number of galls per root system. Seventeen accessions with Meloidogyne spp. and ToRMV resistance were selected and evaluated in Spain against three monopartite Begomovirus spp. associated with the tomato yellow leaf curl virus disease, using infectious clones. Systemic infection was monitored by DNA hybridization. Five S. peruvianum accessions (PI-306811, PI-365951, LA-1609, LA-2553, and CNPH-1194) displayed nematode and broad-spectrum resistance to all Begomovirus spp. tested in both continents. From the breeding standpoint, accessions combining resistance to Meloidogyne spp. and to bipartite and monopartite Begomovirus spp. would be useful for the development of elite lines expressing all traits in homozygous condition.