Table 2.
Clusters of Plant R Genes Characterized by Molecular Analysis
| R-gene locus | Structural subclass | Species | Members of gene family | Size of locus | References |
| Cf2/Cf5 | LRR–TM | tomato | 2+ | N.R. | Jones et al. (1993); Dixon et al. (1996); Hammond-Kosack and Jones (1997) |
| Cf4/Cf9 | LRR–TM | tomato | 5 | 36 kb | Jones et al. (1993); Parniske et al. (1997); Thomas et al. (1997) |
| Dm3 | NBS–LRR | lettuce | 24+ | 4 ± Mb | Farrara et al. (1987); Meyers et al. (1998a) |
| Dm13 | NBS–LRR | lettuce | 13+ | N.R. | Meyers (1998) |
| I2 | NBS–LRR | tomato | 4+ | N.R. | Ori et al. (1997) |
| M | TIH–NBS–LRR | flax | 15± | <1 Mb | Anderson et al. (1997); Ellis et al. (1997) |
| N | TIH–NBS–LRR | tobacco | 4+ | N.R. | Whitham et al. (1994) |
| Pto | kinase | tomato | 5, plus Prf | 65 ± kb | D. Lavelle and R. Michelmore, (unpubl.) |
| RPP5 | TIH–NBS–LRR | Arabidopsis | 7 | 50 ± kb | Parker et al. (1996); Dangl and Holub (1997) |
| Xa21 | LRR–kinase | rice | 8+ | 230 ± kb | Ronald et al. (1992); Song et al. (1995) |
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(N.R.) not reported.
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↵(TIH) Toll–interleukin homology region; (NBS) nucleotide binding site; (LRR) leucine-rich repeats; (TM) transmembrane domain.
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↵Members of the gene family at each locus were determined in a single genotype by mapping of RFLPs resulting from the hybridization of the cloned resistance gene from that locus or by genomic sequencing of the region containing the cluster. This number includes pseudogenes.
