candidate for Lr19, an exotic gene conditioning leaf rust resistance in wheat

• Published in: Functional & integrative genomics Vol. 9; no. 3; pp. 325 - 334
• Main Authors: Gennaro, Andrea, Koebner, Robert M. D, Ceoloni, Carla
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.08.2009; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Amino Acid Sequence; Animal Genetics and Genomics; Base Sequence; Basidiomycota - pathogenicity; Biochemistry; Bioinformatics; Biological and medical sciences; Biomedical and Life Sciences; Cell Biology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; General aspects; Genes, Plant; Genetic markers; Genomics; Immunity, Innate - genetics; Life Sciences; Mathematics in biology. Statistical analysis. Models. Metrology. Data processing in biology (general aspects); Microbial Genetics and Genomics; Molecular Sequence Data; Original Paper; Plant biology; Plant Diseases - microbiology; Plant Genetics and Genomics; Plant Proteins - genetics; Plant Proteins - metabolism; Plant resistance; Recombination, Genetic; Sequence Analysis, DNA; Thinopyrum ponticum; Triticum - genetics; Triticum - microbiology; Triticum aestivum; Wheat; NBS-LRR genes; RGAs; Codominant marker; Monocotyledones; Rust; Triticum durum; Plant leaf; Lr19; Marker; Resistance; Gramineae; Angiospermae; Cereal; Spermatophyta; Candidate gene; Wheat; Triticum aestivum; Thinopyrum ponticum
• ISSN: 1438-793X; 1438-7948
• DOI: 10.1007/s10142-009-0115-1

Lr19, one of the few widely effective genes conferring resistance to leaf rust in wheat, was transferred from the wild relative Thinopyrum ponticum to durum wheat. Since Lr19 confers a hypersensitive response to the pathogen, it was considered likely that the gene would be a member of the major nucleotide-binding site (NBS)-leucine-rich repeat (LRR) plant R gene family. NBS profiling, based on PCR amplification of conserved NBS motifs, was applied to durum wheat-Th. ponticum recombinant lines involving different segments of the alien 7AgL chromosome arm, carrying or lacking Lr19. Differential PCR products were isolated and sequenced. From one such sequence (AG15), tightly linked to Lr19, a 4,121-bp full-length cDNA was obtained. Its deduced 1,258 amino acid sequence has the characteristic NBS-LRR domains of plant R gene products and includes a coiled-coil (CC) region typical of monocots. The genomic DNA sequence showed the presence of two exons and a short intron upstream of the predicted stop codon. Homology searches revealed considerable identity of AG15 with the cloned wheat resistance gene Pm3a and a lower similarity with wheat Lr1, Lr21, and Lr10. Quantitative PCR on leaf-rust-infected and non-infected Lr19 carriers proved AG15 to be constitutively expressed, as is common for R genes.