2.Gene symbols for resistance to bacterial leaf blight

Tsugufumi Ogawa

International Rice Research Institute P. O. Box 933, Manila, Philippines

Genetic studies on resistance to bacterial leaf blight have been conducted mainly in Japan and at IRRI. As the results, Xa-1, Xa-2, Xa-3, and Xa-11 were identified using Japanese isolates of Xanthomonas campestris pv. oryzae in Japan (Sakaguchi 1967; Ezuka et al. 1975; Ogawa and Yamamoto 1986). Xa-kg was identified using an Indonesian isolate in Japan (Ogawa et al. 1978). Furthermore, two alleles of Xa-1 and Xa-kg were recognized using Japanese isolates in Japan and they were designated as Xa-1h and Xa-kgh, respectively (Yamada 1984).

On the other hand, Xa-4, xa-5, Xa-6, Xa-7, xa-8, xa-9, and Xa-10 were identified using Philippine isolates at IRRI (Librojo et al. 1976; Olufowote et al. 1977; Petpisit et al. 1977; Sidhu and Khush 1978; Sidhu et al. 1978; Singh et al. 1983; Yoshimura et al. 1983). Xa-4b was also recognized as an allele of Xa-4 (Librojo et al. 1976; Sidhu et al. 1978, 1979).

Genetic studies have been done only using isolates originating from each country. Therefore, resistant genes identified at two sites could not be compared to each other. From this point, IRRI and Tropical Agriculture Research Center (TARC) in Japan have started a collaborate research on the resistance to rice bacterial leaf blight. To date, the results show that Xa-6, Xa-9 and Xa-4b of Semora Mangga are allelic to Xa-3 (Ogawa et al. 1986).

It is known that Xa-1, Xa-2 and Xa-kg were very closely linked. There is another possibility that Xa-1, Xa-2 and Xa-kg are alleles at the same locus. In addition to this, Xa-1h and Xa-kgh were reported as allelic genes of Xa-1 and Xa-kg. This was analyzed using IR28, IR29 and IR30 (Yamada 1984). These cultivars have Xa-4, which is also effective to Japanese isolates (Ogawa unpublished). Therefore, Xa-1h and Xa-kgh should be compared with Xa-1 and Xa-kg taking the resistance of Xa-4 of IR28, IR29, and IR30 to Japanese isolates into consideration.

Genetic studies on the resistance to bacterial leaf blight have also been done in Sri Lanka, India and China, using isolates obtained in respective countries. Therefore, the exchange of tester varieties and isolates are important for identification of genes. Regarding Xa-1 to Xa-11 and Xa-kg, we preserve the varieties and isolates used for analysis.

Under the collaborate research program between IRRI and Japan, we collected isolates in several Asian countries at TARC, Japan. Therefore, TARC can be a center for storing isolates analyzed in various countries and provide them for cooperative studies in different countries.

List of genes for resistance to bacterial leaf blight are summarized in Table 1.

Table 1. List of genes for resistance to bacterial leaf blight
______________________________________________________________
Gene    Original     Representative Varieties     Remarks
        designation
______________________________________________________________
Xa-1                 Kogyoku
Xa-1h   Xa-1h        IR22, IR29, IR30
Xa-2    Xa-2         Rantai Emas II, Te-tep
Xa-3    Xa-w         Wase Aikoku 3
        Xa-4b        Semora Mangga
        Xa-6         Zenith
        Xa-9         Sateng
Xa-4    Xa-4         TKM 6, IR20, IR22
        Xa-4a  
Xa-5                 DZ192, IR1545-339
Xa-7                 DV85
Xa-8                 P1231129
Xa-1O                Cas 209
Xa-11   Xa-pt        RP9-3
Xa-12   Xa-kg        Kogyoku, Java 14
Xa-12h  Xa-kgh       IR28, IR29, IR30
______________________________________________________________
Gene to be confirmed
        X1          Kogyoku, Shimotsuki   Washio et al. (1967)
        X2                  "                     "
        X3                  "                     "
        Xa-a        Wase Aikoku 3         Watanabe (1976)
        xa-k                "                     "
        Xa-p        Zenith, PI209938              "
        Xa-i                "                     "
        Xa-b        Blue Bonet/Rexark             "
        A           Malagkit Sungsong     Moses et al. (1974)
        B                   "                     "
        R           IRR169/469                    "
        P1          Lacrosse/Zenith-Nira          "
        Ip          IR8                           "
______________________________________________________________

References

Ezuka, A., 0. Horino, K. Toriyama, H. Shinoda and T. Morinaka, 1975. Inheritance of resistance of rice variety Wase Akikoku 3 to Xanthomonas oryzae. Bull. Tokai-Kinki Nat. Agric. Exp. Stn. 28: 124-130.

Librojo, V., H. E. Kaufman and G. S. Khush, 1976. Genetic analysis of bacterial blight resistance in four varieties of rice. SABRAO J. 8: 105-1 10.

Moses, C. J., Y. P. Rao and E. A. Siddiq, 1974. Indian J. Genet. & Plant Breed. 34: 271-279.

Olufowote, J. O., G. S. Khush and H. E. Kauffman,1977. Inheritance of bacterial blight resistance in Rice. Phytopathology 67: 772-775.

Ogawa, T., T. Morinaka, K. Fujii and T. Kimura, 1978. Inheritance of resistance to rice varieties Kogyoku and Java 14 to bacterial group V of Xanthomonas oryzae. Ann. Phytopathol. Soc. Jpn. 44: 137-141.

Ogawa, T. and T. Yamamoto, 1986. Inheritance of resistance of bacterial blight in rice. In Rice Genetics pp. 471-479. IRRI, Manila.

Ogawa, T., T. Yamamoto, G. S. Khush and T. W. Mew, 1986. The relationship between genes Xa-3 and Xa-6 for resistance to bacterial blight. RGN 3: 79-80.

Ogawa, T., T. Yamamoto, G. S. Khush and T. W. Mew, 1986. Inheritance of resistance to bacterial blight in Sateng-A reinvestigation. RGN 3: 80-82.

Ogawa, T., R. E. Tabien, G. A. Busto, G. S. Khush and T. W. Mew, 1986. The relationship between Xa-3, Xa-4, and Xa-4b for resistance to rice bacterial blight. RGN 3: 83-84.

Petpisit, V., G. S. Khush and H. E. Kauffman, 1977. Inheritance of resistance of bacterial blight in rice. Crop Sci. 17: 551-554.

Sakaguchi, S., 1967. Linkage studies on the resistance to bacterial leaf blight, Xanthomonas oryzae (Uyeda et Ishiyama) Dawson in rice. Bull. Nat. Inst. Agric. Sci., Jpn., Ser. D 16: 1-18.

Sidhu, G. S. and G. S. Khush, 1978. Dominance reversal for a bacterial blight resistance gene in some rice cultivars. Phytopathology 68: 461-463.

Sidhu, G. S., G. S. Khush and T. W. Mew, 1978. Genetics analysis of bacterial blight resistance in seventy-four cultivars of rice, Oryza sativa L. Theor. Appl. Genet. 53: 105-111.

Sidhu, G. S., G. S. Khush and T. W. Mew, 1979. Genetic analysis of resistance to bacterial blight in seventy cultivars of rice, Oryza sativa L., from Indonesia. Crop. Improv. 6: 19-25.

Singh, R. J., G. S. Khush and T. W. Mew, 1983. A new gene for resistance to bacterial blight in rice. Crop Sci. 23: 558-560.

Washio, O., K. Kariya and K. Toriyama, 1967. Studies on breeding rice varieties for resistance to bacterial leaf blight. Bull. Chugoku Agric. Exp. Stn. Ser. A 13: 55-85.

Watanabe, S., 1976. Studies on the breeding of rice varieties resistant to bacterial leaf blight in Sri Lanka. Tohoku Natl. Agric. Exp. Stn. 54: 1-74.

Yamada, T., 1984. Multiple alleles at the Xa-1 and Xa-kg loci for resistance to bacterial leaf blight. RGN 1: 97-98.

Yoshimura, A., T. W. Mew, G. S. Khush and T. Omura, 1983. Inheritance of resistance to bacterial blight in rice cultivar Cas 209. Phytopathology 73: 1409-1412.

Yu, G. X., D. P. Zhang and Y. F. Xie, 1986. Location of genes for resistance to Chinese strains of bacterial blight, Xanthomonas campestris pv. oryzae in IR28. RGN 3: 86-87.