products of the broken Tm-2 and the durable Tm-2² resistance genes from tomato differ in four amino acids

• Published in: Journal of experimental botany Vol. 56; no. 421; pp. 2925 - 2933
• Main Authors: Lanfermeijer, Frank C, Warmink, Jan, Hille, Jacques
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.11.2005; Oxford Publishing Limited (England)
• Subjects: Agronomy. Soil science and plant productions; alleles; amino acid sequences; Biological and medical sciences; disease resistance; durability; durable resistance; Fundamental and applied biological sciences. Psychology; gene-for-gene relationship; genes; genetic resistance; Genetics and breeding of economic plants; Lycopersicon esculentum; Lycopersicon peruvianum; molecular sequence data; movement proteins; open reading frames; Pest resistance; plant disease resistance gene; Plant pathogens; resistance breaking; signal transduction; Solanum lycopersicum var. lycopersicum; structure–function relationships; Tm-2; Tm-22; Tomato mosaic virus; tomatoes; transgenic plants; Varietal selection. Specialized plant breeding, plant breeding aims; viral proteins; Tm-22; durability; plant disease resistance gene; Structure function relationship; tomato mosaic virus; Signal transduction; Gene; Dicotyledones; Aminoacid; Angiospermae; Lycopersicon esculentum; structure-function relationships; Tm-2; Spermatophyta; Transgenic plant; Solanaceae; Lycopersicon peruvianum
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/eri288

To gain an insight into the processes underlying disease resistance and its durability, the durable Tm-2² resistance gene was compared with the broken Tm-2 resistance gene. The Tm-2 gene of tomato could be isolated via PCR with primers based on the Tm-2² sequence. The Tm-2 gene, like the Tm-2² gene, encodes an 861 amino acid polypeptide, which belongs to the coiled coil/nucleotide binding site/leucine-rich repeat class of resistance proteins. The functionality and the nature of the isolated Tm-2 gene were confirmed by introducing the gene under the control of the 35S promoter into tomato mosaic virus-susceptible tobacco. This transgenic tobacco was crossed with transgenic tobacco plants producing the movement protein (MP)-authenticated MP as the Avr protein of the Tm-2 resistance. The Tm-2² and Tm-2 open reading frames only differ in seven nucleotides, which on a protein level results in four amino acid differences, of which two are located in the nucleotide binding site and two are located in the leucine-rich repeat domain. The small difference between the two proteins suggests a highly similar interaction of these proteins with the MP, which has major implications for the concept of durability. Comparison of the two resistance-conferring alleles (Tm-2 and Tm-2²) with two susceptible alleles (tm-2 and lptm-2) allowed discussion of the structure-function relationship in the Tm-2 proteins. It is proposed that the Tm-2 proteins display a partitioning of the leucine-rich repeat domain, in which the N-terminal and C-terminal parts function in signal transduction and MP recognition, respectively.