Characterization and linkage mapping of R-gene analogous DNA sequences in pea (Pisum sativum L.) |
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Authors: | G M Timmerman-Vaughan T J Frew N F Weeden |
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Institution: | (1) New Zealand Institute for Crop & Food Research Limited, Private Bag 4704, Christchurch, New Zealand, NZ;(2) Department of Horticultural Science, Cornell University, Geneva NY 14456, USA, Present address: Department of Plant Sciences, Montana State University, Bozeman MT 59717-7622, USA, US |
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Abstract: | Pea (Pisum sativum L.) sequences that are analogous to the conserved nucleotide binding site (NBS) domain found in a number of plant disease
resistance genes (R-genes) were cloned. Using redundant oligonucleotide primers and the polymerase chain reaction (PCR), we
amplified nine pea sequences and characterised their sequences. The pea R-gene analog (RGA)- deduced amino acid sequences
demonstrated significant sequence similarity with known R-gene sequences lodged in public databases. The genomic locations
of eight of the pea RGAs were determined by linkage mapping. The eight RGAs identified ten loci that mapped to six linkage
groups. In addition, the genomic organization of the RGAs was inferred. Both single-copy and multicopy sequence families were
present among the RGAs, and the multicopy families occurred most often as tightly linked clusters of related sequences. Intraspecific
copy number variability was observed in three of the RGA sequence families, suggesting that these sequence families are evolving
rapidly. The genomic locations of the pea RGAs were compared with the locations of known pea R-genes and sym genes involved in the pea-rhizobia symbiosis. Two pea RGAs mapped in the genomic region containing a pea R-gene, Fw, and four pea RGAs mapped in regions of the genome containing sym genes.
Received: 4 August 1999 / Accepted: 11 November 1999 |
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Keywords: | NBS-LRR Disease resistance sym genes Legume-rhizobia symbiosis |
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