Internationa Rice Research Institute, P. O. Box 933, Manila, Philippines
In order to induce new mutants for linkage mapping in rice, seeds of IR68 were presoaked for 16 hrs and then treated with 1.0% EMS solution (prepared in phosphate buffer pH 7.0) for 10.5 hrs at 30 deg C over a temperature controlled shaker. A brittle culm mutant was selected from M`2` population. The true breeding nature of the mutant was confirmed in M3. Inheritance of the mutant was studied by crossing it with IR68. The F`1` was brittle culm and the F`2`
Table 1. F`2` segregation of Bc-6 with IR68 and other brittle culm mutants
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Cross Total Brittle Normal Chi2
plants culm 13:3
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Bc-6/IR68 289 207 82 1.5791/
Bc-6/bc-1 931 740 191 1.791
Bc-6/bc-2 642 516 126 0.267
Bc-6/bc-3 430 352 078 0.069
Bc-6/bc-4 589 464 125 2.204
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1/ Chi2 for 3:1
segregated in 3 brittle culm: 1 normal (Table 1). This brittle culm mutant
is thus controlled by a single dominant gene. To determine its allelic
relationships with other brittle culm mutants it was crossed with bc-1, bc-2,
bc-3 and bc-4. Allele test with bc-5 has not been made as bc-5 shows
brittleness at the nodes only as compared to new mutant in which all plant
parts are brittle. This new dominant brittle culm mutant is designated Bc-6.