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Shigehisa KIYOSAWA
National Institute of Agrobiological Resources, Yatabe, Tsukuba, Ibaraki, 305 Japan
Varieties with different single resistance genes are ideal differential varieties for pathogenicity test of the pathogen (Flor 1945). In Japan, the first differential varieties for rice blast were chosen by Goto and co-workers (1961, 1964). Yamasaki and Kiyosawa (1966) initiated gene analysis using seven fungus strains selected in the light of Goto's work and detected three resistance genes, Pi-a, Pi-i and Pi-k. Since then, 13 genes have been identified (Kiyosawa 1972). Since 1960's, the author has tried to develop lines with a single gene from varieties having more than one gene. For example, resistance gene Pi-ta was isolated from the hybrid between Pi No. 1 having Pi-a and Pi-ta and Norin 8 which has no resistance gene (Kiyosawa 1966). Line K 1 with Pi-ta was thus obtained (Kiyosawa 1967). Also, line K 60 with Pi-kp was obtained from K 2 x Shin 2; K 2 having Pi-a and Pi-kp was derived from Pusur x Norin 22. Pi-kp was first found in Pusur, a variety from Pakistan (Kiyosawa 1969). K 59 with Pi-t was obtained from BL 10 (Pi-b Pi-t) x Kanto 51 (Pi-k) (Kiyosawa 1972).
The strains with different single resistance genes thus obtained, as listed in Table 1, are useful as differential varieties to classify fungus isolates into groups differing in pathogenicity. In addition, another set of differential varieties was established by Yamada et al. (1976, included in Table 1). By the use of these differential varieties, it has become possible to estimate the structure of populations of the blast fungus in terms of frequency of virulence and avirulence genes. However, it is possible that some of these differential varieties have more than one gene if fungus strains of alien origin are tested.
Table 1. Differential varieties and their resistance genes
============================================================================= Differential varieties of Gene Code number Literature Kiyosawa Yamada et al. ============================================================================= Shin 2 Shin 2 Pi-ks 1 Kiyosawa 1969 Aichi Asahi Aichi Asahi Pi-a 2 Kiyosawa et al. 1967 Fujisaka 5 Ishikari-shiroke Pi-i 4 Yamasaki and Kiyosawa 1966 Kusabue Kanto 51 Pi-k 10 Yamasaki and Kiyosawa 1966 Kiyosawa 1968 Tsuyuake Tsuyuake Pi-km 20 Kiyosawa 1978 Fukunishiki Fukunishiki Pi-z 40 Kiyosawa 1970 K 1 Yashiro-mochi Pi-ta 100 Kiyosawa 1967,1969 Pi No. 4 Pi No. 4 Pi-ta2 200 Kiyosawa 1969 Toride 1 Toride 1 Pi-zt 400 Yokoo and Kiyosawa 1970 K 60 Pi-kp .1 Kiyosawa unpublished BL 1 Pi-b .2 Yokoo et a]. 1978 K 59 Pi-t .4 Kiyosawa 1972 ============================================================================= Note: Race number is determined by adding the code number of varieties which show virulent reaction. For example, the race number of isolate which shows virulent reactions to Shin 2 and Kusabue is 1 + 10 = 11.
References
Flor, H. H., 1945. Identification of races of flax rust by lines with single rust-conditioning genes. U.S. Dept. Agr. Tech. Bull. 1087.
Goto, K. (with 10 co-workers), 1961. Joint Work on the Race of Blast Fungus, Piricularia oryzae. Special Report on Forecasting of Occurrence of Disease and Insect Pest, No. 5 pp. 89(in Japanese).
Goto, K. (with 16 co-workers), 1964. Ditto, 2. Special Report on Forecasting of Occurrence of Disease and Insect Pest, No. 18 pp.132 (in Japanese).
Kiyosawa, S., 1966. Studies on inheritance of resistance of rice varieties to blast, 3. Inheritance of resistance of a rice variety Pi No. I to the blast fungus. Jpn. J. Breed. 16: 243-250.
Kiyosawa, S., 1967. Genetic studies on host-pathogen relationship in the rice blast disease. Proc. Symp. Rice Diseases and their Control by Growing Resistant Varieties and Other Measures. Tokyo, p. 137-153.
Kiyosawa, S. 1968. Inheritance of blast resistance in some Chinese rice varieties and their derivatives. Jpn. J. Breed. 18(4): 193-205.
Kiyosawa, S. 1969. Inheritance of resistance of rice varieties to a Philippine fungus strain of Pyricularia oryzae. Jpn. J. Breed. 19(2): 61-73.
Kiyosawa, S. 1970. Comparison among various methods for testing blast resistance of rice varieties. Ann. Phytopath. Soc. Japan 36(5): 325-333 (in Jap.)
Kiyosawa, S. 1972. The inheritance of blast resistance transferred from some indica varieties of rice. Bull. Natl. Inst. Agr. Sci. D23: 69-95.
Kiyosawa, S. 1978. Identification of blast-resistance genes in some rice varieties. Jpn. J. Breed. 28(4): 287-296.
Yamada, M., S. Kiyosawa, T. Yamaguchi, T. Hirano, T. Kobayashi, K.Kushibuchi, and S. Watanabe, 1976. Proposal of a new method for differentiating races of Pyricularia oryzae Cavara in Japan. Ann. Phytopathol. Soc. Japan 42: 216-219.
Yamasaki, Y. and S. Kiyosawa, 1966. Studies on inheritance of resistance of rice varieties to blast, 1. Inheritance of resistance of Japanese varieties to several strains of the fungus. Bull. Natl. Inst. Agr. Sci. D14: 39-69 (in Jap.).
Yokoo, M. and S. Kiyosawa, 1970. Inheritance of blast resistance of the rice variety, Toride 1, selected from the cross Norin 8 x TKM 1. Jpn. J. Breed. 20: 129-132.
Yokoo, M., F. Kikuchi, H. Fujimaki and K. Nagai, 1978. Breeding of blast resistant line (BL 1 to BL 7) from indica-japonica crosses of rice. Jpn. J. Breed. 28: 359-365. (in Jap.)
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