Functional & Integrative Genomics

, Volume 9, Issue 3, pp 325–334

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

  • Andrea Gennaro
  • Robert M. D. Koebner
  • Carla Ceoloni
Original Paper

DOI: 10.1007/s10142-009-0115-1

Cite this article as:
Gennaro, A., Koebner, R.M.D. & Ceoloni, C. Funct Integr Genomics (2009) 9: 325. 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.


Triticum durumThinopyrum ponticumNBS-LRR genesRGAsLr19Codominant marker

Supplementary material

10142_2009_115_Fig1_ESM.gif (106 kb)
Fig. S1

Amino acid sequence comparison of proteins encoded by AG15 and Pm3a genes performed by ClustalW2 software using default parameters. Start positions of CC, NBS and LRR domains are indicated in bold. The AG15 CC domain, identified by Jpred 3 software, is underlined. Conserved motifs, characteristics of the NBS domain of NBS-LRR proteins (in the following order: P-loop, Kinase 2, RNBS-B, GLPL, MHD), are boxed and show complete identity between the two proteins. Intron position, identified in both AG15 (see text) and Pm3a (Yahiaoui et al. 2004) by comparison of the genomic sequences with the cDNA sequences, is conserved between the two genes and located immediately upstream of the stop codon (vertical arrow) (GIF 106 kb)

10142_2009_115_Fig1_ESM.eps (1.2 mb)
High resolution (EPS 1274 kb)
10142_2009_115_Fig2_ESM.gif (14 kb)
Fig. S2

Neighbor-joining phylogenetic tree of AG15 and related cereal proteins encoded by R genes or RGAs. Abbreviation of the Latin species name precedes the protein name (where known) and the accession number. Chromosome location of each sequence is reported in brackets. Proteins encoded by genes isolated in wheat are indicated in bold (GIF 13 kb)

10142_2009_115_Fig2_ESM.eps (453 kb)
High resolution (EPS 1274 kb)

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Andrea Gennaro
    • 1
  • Robert M. D. Koebner
    • 2
  • Carla Ceoloni
    • 1
  1. 1.Department of Agrobiology and AgrochemistryUniversity of TusciaViterboItaly
  2. 2.Department of Crop GeneticsJohn Innes CentreNorwichUK