Tobacco transgenic for the flax rust resistance gene L expresses allele-specific activation of defense responses

• Published in: Molecular plant-microbe interactions Vol. 17; no. 2; pp. 224 - 232
• Main Authors: Frost, D, Way, H, Howles, P, Luck, J, Manners, J, Hardham, A, Finnegan, J, Ellis, J
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.02.2004; American Phytopathological Society; The American Phytopathological Society
• Subjects: alleles; Ascomycota - pathogenicity; Base Sequence; Biological and medical sciences; Cercospora nicotianae; Cloning, Molecular; defense mechanisms; disease resistance; Flax - genetics; Flax - microbiology; Fundamental and applied biological sciences. Psychology; fungal diseases of plants; Gene Expression Regulation, Plant; genes; Immunity, Innate - genetics; L10 allele; L2 allele; L6 allele; Linum usitatissimum; mutants; NBS-LRR resistance genes; necrosis; Nicotiana - genetics; Nicotiana tabacum; Phenotype; Phytopathology. Animal pests. Plant and forest protection; Phytophthora - pathogenicity; Phytophthora nicotianae var. parasitica; Phytophthora parasitica nicotianae; plant defense; Plant Diseases - microbiology; Plant Leaves - microbiology; plant proteins; Plants, Genetically Modified - genetics; Polymerase Chain Reaction; Receptors, Interleukin-1 - genetics; tobacco; transgenic plants; Resistance; Linum usitatissimum; Allele; Linaceae; Gene; Microbiology; Dicotyledones; Angiospermae; Spermatophyta; Solanaceae; Nicotiana tabacum
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/mpmi.2004.17.2.224

Tobacco was transformed with three different alleles (L2, L6, and L10) of the flax rust resistance gene L, a member of the toll interleukin-1 receptor, nucleotide-binding site, leucine-rich repeat (TIR-NBS-LRR) class of plant disease resistance genes. L6 transgenics had a stunted phenotype, expressed several defense response genes constitutively, and had increased resistance to the fungus Cercospora nicotianae and the oomycete Phytophthora parasitica pv. nicotianae. L2 and L10 transgenics, with one exception for L10, did not express these phenotypes, indicating that the activation of tobacco defense responses is L6 allele-specific. The phenotype of the exceptional L10 transgenic plant was associated with the presence of a truncated L10 gene resulting from an aberrant T-DNA integration. The truncated gene consisted of the promoter, the complete TIR region, and 39 codons of the NBS domain fused inframe to a tobacco retrotransposon-like sequence. A similar truncated L10 gene, constructed in vitro, was transiently expressed in tobacco leaves and gave rise to a strong localized necrotic reaction. Together, these results suggest that defense signaling properties of resistance genes can be expressed in an allele-specific and pathogen-independent manner when transferred between plant genera.