Table 1.
Clusters of Plant R Genes Identified by Classical Genetics
| Species | R-gene locus | Linked resistance specificities | No. of pathogens detected | Size (cM) | References |
| Arabidopsis | MRC-F | 6RPP genes,RAC2 | 2 | 10+ | Kunkel (1996); Holub (1997) |
| Arabidopsis | MRC-H | 5 RPPgenes, RPS2, TOM1 | 3 | 15± | Kunkel (1996); Holub (1997) |
| Arabidopsis | MRC-J | 5 RPPgenes, RAC3, RPS4, HRT1, TTR1 | 5 | 15± | Kunkel (1996); Holub (1997) |
| Barley | Mla | 18 Mlagenes | 1 | 0 | Jahoor et al. (1993); Jorgenson (1994) |
| Flax | L | 13 Lalleles | 1 | 0 | Islam and Shepherd (1991) |
| Flax | M | 7 Mgenes | 1 | <1 | Flor (1965); Mayo and Shepherd (1980) |
| Flax | N | N, N1, N2 | 1 | <1 | Islam and Shepherd (1991); Ellis et al. (1997) |
| Flax | P | 7 Pgenes | 1 | 0 | Islam and Shepherd (1991); Ellis et al. (1997) |
| Lettuce | Dm1/3 | 8+ Dm genes,Ra | 2 | 20 | Farrara et al. (1987); Kesseli et al. (1994) |
| Lettuce | Dm5/8 | 4 Dm genes,Tu, Mo2, plr | 4–5 | 9 | Farrara et al. (1987); Witsenboer et al. (1995); Kesseli et al. (1994) |
| Lettuce | Dm4/7 | 5+ Dmgenes | 1 | 0 | Farrara et al. (1987) |
| Maize | Rp1 | 14 Rp1 genes (A–N), Rp5, Rp6, Rpp9 | 2 | 3 | Saxena and Hooker (1968); Hooker (1985);Bennetzen et al. (1991) |
| Maize | Rp3 | 6 Rp3genes (A–F) | 1 | N.R. | Saxena and Hooker (1974); Sanz-Alferez et al. (1995) |
| Potato | chromosome 5 | R1, Pi01–QTL, Rx2, Gpa | 3 | N.R. | Leister et al. (1996) |
| Rice | chromosome 11 | 4+ Xa genes, 5+Pi genes, 1 QTL | 2 | 30 | Yoshimura et al. (1983);Mackill and Bonman (1992); Kinoshita (1993) |
| Soybean | linkage group F | Rsv1, Rpv, Rps3 | 3 | N.R. | Diers et al. (1992); Yu et al. (1994) |
| Soybean | linkage group J | Rps2, Rmd, Rj2, 1 QTL | 3–4 | 3.8 | Polzin et al. (1994); Kanazin et al. (1996) |
| Tomato | Cf2, Cf5 | Cf2, Cf5, Ol-1, TY-1, Mi, Meu-1 | 5 | N.R. | Dickinson et al. (1993); Jones et al. (1993); Van der Beek et al. (1994); Zamir et al. (1994); Kaloshian et al. (1995) |
| Tomato | Cf4/9 | Cf1, Cf4, Cf9 | 1 | 0 | Kerr and Bailey (1964); Jones et al. (1993) |
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(N.R.) Not reported; usually because genes segregated in different crosses.
