Isolation and linkage analysis of expressed disease-resistance gene analogues of sugar beet (Beta vulgaris L.).
Sequence conservation among resistance genes (R genes) was exploited to identify 47 R gene analogues (RGAs) from sugar beet (Beta vulgaris L.). Using degenerate primers, 11 RGAs were amplified from genomic DNA and 7 from leaf or beet cDNA. Twenty-nine were selected from an EST sequencing program. Twenty-one RGAs contained structures similar to the nucleotide binding site (NBS)--leucine rich repeat (LRR) domain, a motif commonly found in several R genes. Among the remaining RGAs, 19 revealed similarity to the serine (threonine) protein kinase domain of R genes, 4 showed features related to the LRR region of the rice disease resistance gene Xa21, 1 RGA resembled the sugar beet nematode resistance gene Hs1pro-1, and 2 had homologies to other gene products associated with disease resistance. For 20 EST-derived RGAs, transcript levels were compared in leaf and root tissue revealing organ-specific transcription in 7 cases. Thirty-three RGAs were spread over all nine sugar beet chromosomes, except for a cluster of nine closely linked RGAs on chromosome 7. The analysis of linkage between RGAs and loci for rhizomania and Cercospora resistance identified alleles associated with resistance in both cases.
Hunger
Sandra
S
Max Planck Institut für Züchtungsforschung, Carl von Linné Weg 10, 50829 Köln, Germany.
Di Gaspero
Gabriele
G
Möhring
Slike
S
Bellin
Diana
D
Schäfer-Pregl
Ralf
R
Borchardt
Dietrich C
DC
Durel
Charles-Eric
CE
Werber
Martin
M
Weisshaar
Bernd
B
Salamini
Francesco
F
Schneider
Katharina
K
D027461:Beta vulgaris / Q000235:genetics* / Q000382:microbiology; D002874:Chromosome Mapping; D020224:Expressed Sequence Tags; D005658:Fungi / Q000472:pathogenicity; D008040:Genetic Linkage; D016678:Genome; D016133:Polymerase Chain Reaction