1) Faculty of Agriculture, Hokkaido University, Sapporo, 060 Japan
2) Zennou, 8-3 Ohtemachi 1-chome, Chiyoda-ku, Tokyo, 100 Japan
Gene symbolization for the blast resistance was discussed anew in the Committee and the conclusion was reported in RGN 10, p.11. To avoid confusion and to conform to the rules of gene nomenclature in rice (see RGN 3 p.4-5), new blast resistance genes are designated as Pi followed by a numeral, except ones reported before this time. Thus the gene symbols assigned by Dr. Kiyosawa and others are retained and the priority will be protected. The suffix(t) (tentative) will be attached until the completion of allelism test.
Eleven genes for complete (true) resistance were newly designated : Pi-1 to Pi-11 as shown in Table 1 in accordance with the proposal (1993; RGN 10, p.11). Mackill and Bonman (1992) developed 22 near-isogenic lines (NILS) each having a single complete (true) resistance gene from C039. When the inheritance was studied using the NILS, at least four independent loci, Pi-1(t) to Pi-4(t) and Pi-4a(t) were identified. Inukai et al. (1994) showed that Pi-1 (t) and Pi-3 (t) were different from any resistance genes that had already been reported; Pi-2 (t) was allelic to Pi-z, and Pi-4a(t) was identified to be Pita. Therefore, suffix(t) is removed from Pi-1(t) and Pi-3t, and gene symbol Pi-ta is used instead of Pi-4a(t). Because Pi-2(t) was allelic to Pi-z, Pi-z is used for showing the locus and the first letter of the donor variety 5173 is given as a superscript as Pi-z5.
Wang et al. (1994) produced recombinant inbred lines from a cross between C039 and Moroberekan, and identified at least two complete resistance genes, Pi-5(t) and Pi-7(t) in Moroberekan. Yu et al. (in preparation) used doubled haploid lines to identify Pi-6(t) in Apura. Pi-8(t) in IRAT13 was also identified using doubled haploid lines (CIAT 1991). Reamers et al. (in preparation) identified Pi-9(t) in a diploid line recovered from a cross between the allotetraploid O. minuta and an elite O. sativa breeding line. Naqvi et al. (in preparation) identified Pi-10(t) in Tongil, and Zhu (pers. comm.) identified Pi-zh in Zhaiyeqing.
Goto (1988) reported Pi-kur1 and Pi-kur 2 having an additive effect as field resistance genes. Wang et al. (1994) also mapped ten QTLs of the partial (field) resistance genes by using the recombinant inbred lines from the cross involving Moroberekan. The designation of these genes will be discussed elsewhere (perhaps on the occasion of 4th IRGS).
Thus, the newly revised gene symbols for blast resistance are enumerated as shown in Table 1.
Table 1. List of blast resistance genes newly revised
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Gene symbol Donor variety Chromosomal Relationship Reference
Original Revised location already-known genes
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Pi-1(t) Pi-1 LAC23 11 linked to Pi-k Mackill and Bonman
1992
Yu et al.(in prep-
aration)
Inukai et al. 1994
Pi-2(t) Pi-Z5 5173 6 allelic to Pi-z Mackill and Bonman
1992
Yu et al. 1991
Inukai et al. 1994
Pi-3(t) Pi-3 Pai-kan-tao linkcd to Pi-i Mackill and Bonman
1992
Pi-4a(t) Pi-ta Inukai et al. 1994
Pi-5(t) Moroberekan 4 Wang et al. 1994
Pi-6(t) Apura 12 Yu et al. (in prep-
aration)
Pi-7(t) Moroberekan 11 Wang et al. 1994
Pi-8(t)* IRAT 13 4 CIAT 1991
Pi-9(t) O. minuta Reimers el al. (in
preparation)
Pi-10(t) Tongil 5 Naqvi el al. (in
preparation)
Pi-zh* Pi-11(t) Zhaiyeqing 8 Zhu (pers. comm.)
Pi-kur1 Kuroka 4 Goto 1988
Pi-kur2 Kuroka 11 Goto 1988
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* Convener is communicating with the authors for revision.
ReferencesCIAT (Centro Internacional de Agricultura Tropical) Annual Report, 1991. Tagging resistance genes to Colombian isolates of rice blast with RFLP and RAPD markers. Apartado Aereo 6713, Cali, Colombia. pp. 51-56.
Goto, I., 1988. Genetic studies on resistance of rice plant to blast fungus (VII). Blast resistance genes of Kuroka. Ann. Phytopath. Soc. Japan 54: 460-465.
Inukai, T., Nelson, R. J., Zeigler, R. S., Sarkarung, S., Mackill, D. J., Bonman, J. M., Takamure, I. and Kinoshita, T., 1994. Allelism of blast resistance genes in near-isogenic lines of rice. Phytopathology 84: 1278-1283.
Mackill, D. J. and Bonman, J. M., 1992. Inheritance of blast resistance in near-isogenic lines of rice. Phytopathology 82: 746-749.
Wang, G.L., Mackill, D. J., Bonman, J. M., McCouch, S. R., Champoux, M. C. and Nelson, R. J., 1994. RFLP mapping of genes conferring complete and partial resistance of blast in a durably resistant rice cultivar. Genetics 136: 1421-1434.
Yu, Z. H., Mackill, D. J., Bonman, J. M. and Tanksley, S. D., 1991. Tagging genes for blast resistance in rice via linkage to RFLP markers. Theor. Appl. Genet. 81: 471-476.