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

Caro M, Verlaan MG, Julián O, Finkers R, Wolters AM, Hutton SF, Scott JW, Kormelink R, Visser RG, Díez MJ, Pérez-de-Castro A, Bai Y - Mol. Breed. (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands ; Graduate School Experimental Plant Sciences, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus

Unrooted phylogenetic tree of protein sequences of Ty-1/Ty-3 RDR of accessions of S. chilense and other (wild) tomato species. The RDR proteins of the TYLCV-resistant S. chilense accessions cluster in one clade, as indicated
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Fig3: Unrooted phylogenetic tree of protein sequences of Ty-1/Ty-3 RDR of accessions of S. chilense and other (wild) tomato species. The RDR proteins of the TYLCV-resistant S. chilense accessions cluster in one clade, as indicated

Mentions: RDR protein sequences were derived from the cDNA sequences and aligned (Figure S7). A small number of Ty-1/Ty-3-specific amino acids were observed, which were shared by TYLCV-resistant S. chilense accessions LA1969 (Ty-1), LA2779 (Ty-3), LA1932 (Ty-3A), LA1938, LA1971, and introgression lines BTI-87 and Gh13 reported to contain Ty-3 alleles (Menda et al. 2014; Mejía et al. 2005). These amino acids are L563, V616, and Q919 (numbering based on the Ty-1 allele, SEQ2 in Patent No. WO2012125025). They are absent in S. chilense accessions G1.1556 and G1.1558 that do not contain Ty-1 or Ty-3 (Fig. 2). A phylogenetic analysis using an unrooted tree grouped together the proteins of seven S. chilenseTy-1/Ty-3 alleles responsible for TYLCV resistance (Fig. 3).Fig. 2


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

Caro M, Verlaan MG, Julián O, Finkers R, Wolters AM, Hutton SF, Scott JW, Kormelink R, Visser RG, Díez MJ, Pérez-de-Castro A, Bai Y - Mol. Breed. (2015)

Unrooted phylogenetic tree of protein sequences of Ty-1/Ty-3 RDR of accessions of S. chilense and other (wild) tomato species. The RDR proteins of the TYLCV-resistant S. chilense accessions cluster in one clade, as indicated
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4442973&req=5

Fig3: Unrooted phylogenetic tree of protein sequences of Ty-1/Ty-3 RDR of accessions of S. chilense and other (wild) tomato species. The RDR proteins of the TYLCV-resistant S. chilense accessions cluster in one clade, as indicated
Mentions: RDR protein sequences were derived from the cDNA sequences and aligned (Figure S7). A small number of Ty-1/Ty-3-specific amino acids were observed, which were shared by TYLCV-resistant S. chilense accessions LA1969 (Ty-1), LA2779 (Ty-3), LA1932 (Ty-3A), LA1938, LA1971, and introgression lines BTI-87 and Gh13 reported to contain Ty-3 alleles (Menda et al. 2014; Mejía et al. 2005). These amino acids are L563, V616, and Q919 (numbering based on the Ty-1 allele, SEQ2 in Patent No. WO2012125025). They are absent in S. chilense accessions G1.1556 and G1.1558 that do not contain Ty-1 or Ty-3 (Fig. 2). A phylogenetic analysis using an unrooted tree grouped together the proteins of seven S. chilenseTy-1/Ty-3 alleles responsible for TYLCV resistance (Fig. 3).Fig. 2

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands ; Graduate School Experimental Plant Sciences, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus