Resistance toTomato yellow leaf curl virusAccumulation in the Tomato Wild RelativeSolanum habrochaitesAssociated with the C4 Viral Protein

Abstract

Tomato yellow leaf curl disease (TYLCD) is a severe threat to tomato crops worldwide and is caused by Tomato yellow leaf curl virus (TYLCV) and several other begomoviruses (genus Begomovirus, family Geminiviridae). Host plant resistance is the best TYLCD control method but limited sources of resistance are available. In this study, two Solanum habrochaites TYLCD-resistance sources, EELM-388 and EELM-889, were found after a wide germplasm screening and were further characterized. A consistent resistance to the widely distributed strain TYLCV-IL was observed when plants were inoculated by Bemisia tabaci or by agroinoculation using an infectious clone, with no symptoms or virus accumulation observed in inoculated plants. Moreover, the resistance was effective under field conditions with high TYLCD pressure. Two independent loci, one dominant and one recessive, were associated with EELM-889 resistance. The study shows these loci to be distinct from that of the resistance gene (Ty-1 gene) commonly deployed in commercial tomato cultivars. Therefore, both kinds of resistance could be combined to provide improved resistance to TYLCD. Four additional TYLCD-associated viruses were challenged, showing that the resistance always prevented symptom expression, although systemic infection could occur in some cases. By using chimeric and mutant expression constructs, the C4 protein was shown to be associated with the ability to result in effective systemic infection.

Characterization of a New World Monopartite Begomovirus Causing Leaf Curl Disease of Tomato in Ecuador and Peru Reveals a New Direction in Geminivirus Evolution

“…Finally, the reappearance of wild-type symptoms after graft transmission of the PA98-2 c4 mutant was associated with reversion of the mutation. Based on these results and studies of C4 function in OW begomoviruses (66)(67)(68)(69)(70)(71), the ToLDeV C4 could be involved in movement and suppression of host defense responses. The recovery phenotype in begomovirusinfected plants is a host defense response that involves methylation of the viral genome and a reduction in viral titer and symptom severity (56,69,72).…”

Arabidopsis thaliana, an experimental host for tomato yellow leaf curl disease‐associated begomoviruses by agroinoculation and whitefly transmission

“…Among monopartite begomoviruses, TYLCD‐associated viruses (Navas‐Castillo et al ., ) are excellent candidates for investigating aspects related to begomovirus–plant–vector interactions, due to the large and interesting amount of biological information available for them. This includes virus species and strains that differ in their host range/induction of symptoms (Navas‐Castillo et al ., ; Monci et al ., ), or the ability to confront resistance genes (García‐Andrés et al ., ; Tomás et al ., ). The present investigation demonstrated that A. thaliana was a suitable host to support local replication and systemic accumulation of TYLCV by using A. tumefaciens ‐mediated inoculation.…”

Recessive Resistance Derived from Tomato cv. Tyking-Limits Drastically the Spread of Tomato Yellow Leaf Curl Virus

“…Agrobacterium tumefaciens- mediated stem puncture inoculation (agroinjection) with TYLCV-IL was conducted on plants at the three-leaf growth stage as described previously [ 20 ]. Also, for TYLCV-IL local accumulation studies, A. tumefaciens- mediated leaf tissue infiltration (agroinfiltration) studies were conducted following Tomás et al [ 21 ]. Either for agroinjection or for agroinfiltration, bacterial suspensions at OD 600 = 1.0 were used.…”

“…Virus presence was analyzed in young leaves of inoculated plants by tissue-blot hybridization of freshly cross-sectioned leaf petioles or by Southern blot hybridization of total nucleic acid (TNA), according to Tomás et al [ 21 ] using a probe specific to TYLCV-IL. To monitor virus accumulation in young leaf tissues of TX 468-RG and MM plants inoculated with TYLC-IL, dot blot hybridization analyses were conducted.…”