1)International Rice Research Institute, PO Box 933, Manila Philippines
2) Tropical Agriculture Research Center, Tsukuba, Ibaraki, 305 Japan
More then three thousand rice varieties have been found to be resistant to
bacterial blight on the basis of screening conducted with Philippine race 1 at
International Rice Research Institute (IRRI), Philippines. Out of these, about
1400 varieties were inoculated with four Philippine races to determine their
reaction to these races. Approximately 400 varieties were crossed with IR24
which is susceptible to all the known races. The F\1\ progenies of these
crosses were also inoculated with four Philippine races. Based on the reaction
patterns of these varieties and F\1\ hybrids, these varieties could be grouped
into main groups as follows:
Java 14 group.
The varieties of this group are resistant to four Philippine races of bacterial
blight and develop brownish areas around bacterial blight lesions. When these
varieties are inoculated at maximum tillering stage, the lesion length is
slightly longer than that of other resistant varieties. Moreover, they show
highly resistant reaction at booting and flowering stages. Their F\1\ hybrids
with IR24 are resistant at booting and flowering stages. These varieties have
Xa-3 for resistance. Zenith, Wase Aikoku 3 and Sateng belong to this group.
Varieties of this group come from Indonesia, Bangladesh, Philippines, Laos, and
Korea and are most widely distributed as compared to other varietal groups
(Table 1). Many varieties with Xa-3 belong to Bulu group. Some tropical upland
Japonicas also fall into this group.
TKM 6 group.
Varieties of this group are resistant to race 1 and moderately resistant to
race 4, but are susceptible to races 2 and 3. They have Xa-4 for resistance and
their F\1s\ with IR24 are likewise resistant to race 1 but susceptible races
2 and moderately resistant to race 4. Varieties of this group are typical
Indicas and come from Bangladesh, Central India, Sri Lanka, and Indonesia
(Table 1).
DZ 192 group
Varieties of this group have stable reaction to bacterial blight. They are
resistant to races 1,2 and 3 but only moderately resistant to race 4. Moreover,
these varieties are resistant even at seedling stage.
These varieties have xa-5 for resistance. Their F\1\ hybrids with IR24 are
susceptible. Varieties of this group come from Northeast India, Bangladesh, and
Nepal (Table 1). Many belong to Aus group.
All these varieties belonging to different groups were inoculated at TARC with seven Japanese races. Some varieties of Java 14 and TKM 6 groups appeared to have one additional gene, Xa-1.
Table 1. Distribution of varieties classified from reaction pattern to four
Philippine races of bacterial blight
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Country of Origin No. belonging to different groups:
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Java 14 TKM6 DZ192
Group Group Group
(Xa-3) (Xa-4) (Xa-5)
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Korea 5
China 5
China, Taiwan 5 1
Vietnam 2 2 2
Cambodia 1 1
Laos 9 9
Thailand 8 4
Malaysia 1 1
Burma 1 9 3
Bangladesh 72 46 360
Nepal 1 17
India 61 74
Pakistan 1 10
Sri Lanka 1 59 2
Indonesia 204 42 4
Egypt 3
Ivory Coast 9
Liberia 13 9
Malagasy 4
Iran 2
Zaire 3 1
Brazil 3 1
Argentina 2
U.S.A. 3
Surinam 2 3
Others 4 3
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