Assessing the genetic variation of Ty-1 and Ty-3 alleles conferring resistance to tomato yellow leaf curl virus in a broad tomato germplasm

• Published in: Molecular breeding Vol. 35; no. 6; pp. 132 - 13
• Main Authors: Caro, Myluska, Verlaan, Maarten G., Julián, Olga, Finkers, Richard, Wolters, Anne-Marie A., Hutton, Samuel F., Scott, John W., Kormelink, Richard, Visser, Richard G. F., Díez, Maria J., Pérez-de-Castro, Ana, Bai, Yuling
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2015; Springer Nature B.V
• Subjects: Alleles; Amino acids; Biomedical and Life Sciences; Biotechnology; Catalysis; Cloning; Cultivars; Disease resistance; DNA-directed RNA polymerase; EPS; Gene mapping; Gene sequencing; Gene silencing; Genes; Genetic diversity; Genetics; Germplasm; Insertion; Laboratorium voor Plantenveredeling; Laboratorium voor Virologie; Laboratory of Plant Breeding; Laboratory of Virology; Leaf-curl; Life Sciences; Mapping; Molecular biology; PBR Biodiversiteit en Genetische Variatie; PBR Biodiversity and genetic variation; Plant biology; Plant Breeding; Plant diseases; Plant Genetics and Genomics; Plant Pathology; Plant Physiology; Plant Sciences; Ribonucleic acid; RNA; RNA polymerase; RNA-directed RNA polymerase; Solanum chilense; Tomatoes; Transcription; Viruses; Yellow leaf; Resistance; RNA-dependent RNA polymerase (RDR); Virus-induced gene silencing (VIGS); Tomato yellow leaf curl virus (TYLCV); Tomato; Breeding
• ISSN: 1380-3743; 1572-9788
• DOI: 10.1007/s11032-015-0329-y

Tomato yellow leaf curl virus (TYLCV) hampers tomato production worldwide. Our previous studies have focussed on mapping and ultimately cloning of the TYLCV resistance genes
Ty
-
1
and
Ty
-
3
. Both genes are derived from
Solanum chilense
and were shown to be allelic. They code for an RNA-dependent RNA polymerase (RDR) belonging to the RDRγ type defined by a DFDGD catalytic domain. In this study, we first fine-mapped the TYLCV resistance in
S. chilense
LA1932, LA1960 and LA1971. Results showed that chromosomal intervals of the causal genes in these TYLCV-resistant accessions overlap and cover the region where
Ty
-
1/Ty
-
3
is located. Further, virus-induced gene silencing was used to silence
Ty
-
1
/
Ty
-
3
in tomato lines carrying TYLCV resistance introgressed from
S. chilense
LA1932, LA1938 and LA1971. Results showed that silencing
Ty
-
1/Ty
-
3
compromised the resistance in lines derived from
S. chilense
LA1932 and LA1938. The LA1971-derived material remained resistant upon silencing
Ty
-
1/Ty
-
3
. Further, we studied the allelic variation of the
Ty
-
1/Ty
-
3
gene by examining cDNA sequences from nine
S. chilense
-derived lines/accessions and more than 80 tomato cultivars, landraces and accessions of related wild species. The DFDGD catalytic domain of the
Ty
-
1/Ty
-
3
gene is conserved among all tomato lines and species analysed. In addition, the 12 base pair insertion at the 5-prime part of the
Ty
-
1/Ty
-
3
gene was found not to be specific for the TYLCV resistance allele. However, compared with the susceptible
ty
-
1
allele, the
Ty
-
1/Ty
-
3
allele is characterized by three specific amino acids shared by seven TYLCV-resistant
S. chilense
accessions or derived lines. Thus,
Ty
-
1/Ty
-
3
-specific markers can be developed based on these polymorphisms. Elevated transcript levels were observed for all tested
S. chilense
RDR
alleles (both
Ty
-
1
and
ty
-
1
alleles), demonstrating that elevated expression level is not a good selection criterion for a functional
Ty
-
1/Ty
-
3
allele.