Knotted1-like homeobox (KNOX) genes are essential for the formation/maintenance of the shoot apical meristem (SAM) in plants, and are specifically expressed in the SAM, but are repressed in lateral organs such as leaves. Ectopic expression of KNOX genes in lateral organs was shown to result in abnormal shoot development. To elucidate genetic mechanisms of the SAM-specific expression of KNOX genes, we identified three recessive mutants onion1 (oni1), oni2 and oni3 that developed abnormal shoots in a rice Tos17 mutant panel. Expression analysis showed that four rice KNOX genes OSH1, OSH6, OSH15 and OSH71, but not OSH43, were ectopically expressed in all mutant leaves. Genetic mapping revealed that ONI1 was located on a short arm of chromosome 3, ONI2 on a long arm of chromosome 10 and ONI3 on a long arm of chromosome 9. These results suggested the presence of multiple loci involved in the repression KNOX gene expression in rice leaves.
- Abnormal shoot mutant
- Ectopic expression of KNOX genes
- Genetic mapping
- Leaf development