The Tomato Yellow Leaf Curl Virus Resistance Genes Ty-1 and Ty-3 Are Allelic and Code for DFDGD-Class RNA–Dependent RNA Polymerases

Abstract

Tomato Yellow Leaf Curl Virus Disease incited by Tomato yellow leaf curl virus (TYLCV) causes huge losses in tomato production worldwide and is caused by different related begomovirus species. Breeding for TYLCV resistance has been based on the introgression of multiple resistance genes originating from several wild tomato species. In this study we have fine-mapped the widely used Solanum chilense–derived Ty-1 and Ty-3 genes by screening nearly 12,000 plants for recombination events and generating recombinant inbred lines. Multiple molecular markers were developed and used in combination with disease tests to fine-map the genes to a small genomic region (approximately 70 kb). Using a Tobacco Rattle Virus–Virus Induced Gene Silencing approach, the resistance gene was identified. It is shown that Ty-1 and Ty-3 are allelic and that they code for a RNA–dependent RNA polymerase (RDR) belonging to the RDRγ type, which has an atypical DFDGD motif in the catalytic domain. In contrast to the RDRα type, characterized by a catalytic DLDGD motif, no clear function has yet been described for the RDRγ type, and thus the Ty-1/Ty-3 gene unveils a completely new class of resistance gene. Although speculative, the resistance mechanism of Ty-1/Ty-3 and its specificity towards TYLCV are discussed in light of the function of the related RDRα class in the amplification of the RNAi response in plants and transcriptional silencing of geminiviruses in plants.

Highly Efficient Agroinoculation Method for Tomato Plants with <i>Tomato Yellow Leaf Curl Kanchanaburi Virus</i>

“…With increasing international importance of leaf curl disease in tomatoes, increased efforts have been made to identify resistance to tomato leaf curl disease and incorporate it into improved tomato cultivars (Kenyon et al, 2014). To date, five major genes for resistance or tolerance to TYLCV (Ty-1-Ty-5) have been identified from wild tomato relatives, and some major genes have been incorporated into commercial cultivars in different areas (Anbinder et al, 2009;Hutton et al, 2012;Ji et al, 2007Ji et al, , 2009Lapidot et al, 2015;Verlaan et al, 2013;Zamir et al, 1994). However, whether Ty-1-Ty-5 genes also show resistance or tolerance to local begomovirus species of Southeast Asia is unknown.…”

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

“…Of them, Ty-1 and Ty-3 resistance genes have been cloned and found to encode the DFDGD motif, which belongs to the RNA-dependent RNA g polymerase family (Verlaan et al, 2013). However, cloning of the remaining TYLCV resistance genes has not been reported.…”

Inoculation of Capsicums with <i>Pepper Yellow Leaf Curl Indonesia Virus</i> by Combining Agroinoculation and Grafting

“…With the increasing international importance of leaf curl disease in tomatoes, immense efforts have been made to identify resistance mechanisms to tomato leaf curl disease and incorporate these mechanisms into improved tomato cultivars (Kenyon et al, 2014). To date, five major genes for resistance or tolerance to Tomato yellow leaf curl virus (TYLCV) (Ty-1-Ty-5) have been identified in wild tomato relatives, and some major genes have been incorporated into commercial cultivars in different areas (Anbinder et al, 2009;Hutton et al, 2012;Ji et al, 2007Ji et al, , 2009Lapidot et al, 2015;Verlaan et al, 2013;Zamir et al, 1994). However, resistance to begomovirus infection is much less advanced in peppers compared to tomatoes, and there are as yet no commercial pepper cultivars carrying resistance or tolerance to begomovirus infection (Kenyon et al, 2014).…”