31. Near-isogenic lines as international differentials for resistance to bacterial blight of rice

Tsugufumi Ogawa 1,2, Tsuyoshi Yamamoto2, G.S. Khush1, T.W. Mew1 and Hisatoshi Kaku2

1) International Rice Research Institute, PO Box 933, Manila Philippines

2) Tropical Agriculture Research Center, 1-3 Ohwashi, Tsukuba, Ibaraki-ken, 305 Japan


Different sets of differential cultivars have been utilized for characterizing races of bacterial blight in different countries. Thus there are Japanese differentials and Philippine differentials. A universal system of race identification is not possible without using an international set of differentials. Near isogenic lines with different genes for resistance are ideal for establishing an international differential set. Such an international differential set can be utilized not only for identifying races but also for identifying new genes for resistance. Moreover, isogenic lines can serve as donors for resistance in breeding program and are excellent materials for studying the mechanism of resistance.


Table 1. Near-isogenic lines for resistance to bacterial blight of rice developed to date.

===============================================================================
Designation       Cross1              Generation           R gene
===============================================================================
Ir BB     1   Ir24*5/Kogyoku             BC\4\F\4\        Xa-1 (Xa-12)
IR BB   101   Toyo*5/Kogyoku                "               "     "
IR BB   201   M 23*5/Kogyoku                "               "     "
IR BB     3   IR24*5/Chugoku 45          BC\4\F\6\        Xa-3
IR BB   103   Toyo*5/Chugoku 45             "               
IR BB   203   M 23*5/Chugoku 45          BC\4\F\7\          "
IR BB    3J   IR24*5/Java 14             BC\4\F\6\          "
IR BB  103J   Toyo*5/Java 14                "               "
IR BB  203J   M 23*5/Java 14                "               "
IR BB    3Z   IR24*5/Zenith                 "               "
IR BB  103Z   Toyo*5/Zenith                 "               "
IR BB  203Z   M 23*5/Zenith                 "               "
IR BB    3S   IR24*5/Sateng                 "               "
IR BB  103S   Toyo*5/Sateng                 "               "
IR BB  203S   M 23*5/Sateng                 "               "
IR BB     4   IR24*5/IR20                   "             Xa-4
IR BB   104   Toyo*5/IR20                   "               "
IR BB   204   M 23*5/IR20                   "               "
IR BB     5   IR24*5/IR1545-339         BC\4\F\5\         xa-5
IR BB   105   Toyo*5/IR1545-339         BC\4\F\4\           "
IR BB   205   M 23*5/IR1545-339         BC\4\F\4\           "
IR BB     7   IR24*5/DV85               BC\4\F\7\         Xa-7
IR BB   107   Toyo*5/DV85               BC\4\F\4\           "
IR BB   207   M 23*5/DV85               BC\4\F\5\           "
IR BB     8   IR24*5/PI231129               "             xa-8
IR BB   108   Toyo*5/PI231129               "               "
IR BB   208   M 23*5/PI231129               "               "
IR BB    10   IR24*5/Cas 209            BC\4\F\6\         Xa-10
IR BB   110   Toyo*5/Cas 209            BC\4\F\5\           "
IR BB   210   M 23*5/Cas 209            BC\4\F\6\           "
IR BB    11   IR24*5/IR8                BC\4\F\4\         Xa-11
IR BB   111   Toyo*5/IR8                    "               "
IR BB   211   M 23*5/IR8                    "               "
===============================================================================
1Toyo=Toyonishiki, M 23=Milyang 23.
===============================================================================
For developing near-isogenic lines for bacterial blight resistance, a collaborative project between the Ministry of Agriculture, Forestry and Fisheries (MAFF) of Japan through the Tropical Agriculture Research Center (TARC) and International Rice Research Institute (IRRI) was initiated in 1981. We crossed all the donors with known genes for resistance (Ogawa 1987) to IR24, Milyang 23 and Toyonishiki. Respective hybrids were backcrossed at least 4 times using IR24, Milyang 23 and Toyonishiki as recurrent parents. The recurrent parents were selected on the basis of their susceptibility to all the known races of bacterial blight in Japan and Philippines. During the backcrossing program, progenies were evaluated for resistance using Philippine races at IRRI and Japanese races at TARC (Ogawa and Yamamoto, 1987). The near isogenic lines developed so far are listed in Table 1. We are continuing to backcross newly identified genes using three recurrent parents mentioned above. Seeds of near isogenic lines are available for distribution to scientists interested in investigations on this important disease of rice. Please write either to Dr. T. Ogawa at TARC or Dr. G. S. Khush at IRRI.



References

Ogawa, T., 1987. Gene symbols for resistance to bacterial blight. RGN 4: 41-43.

Ogawa, T., and T. Yamamoto, 1987. Selection of recurrent parents to develop near-isogenic lines resistant to bacterial blight of rice. JARQ 21: 65-69.