Abstract
Rice is a known Si-accumulator, however, the molecular mechanism responsible for high Si uptake by the roots is not understood. In the present study, we isolated a novel rice mutant (lsi2), which was defective in Si uptake. Physiological study showed that this mutant was defective in xylem loading of Si rather than the transport of Si from external solution to root cortical cells. Genetic analysis showed that the low Si uptake was controlled by a recessive gene. To map this gene, bulk segregant analysis was performed by pooling equal amounts of DNA from 10 low-Si uptake or 10 high-Si uptake F2 plants. Both microsatellite and EST-PCR markers were used for mapping the gene. As a result, the gene was mapped to the chromosome 3, which location is different from that of Lsi1, another gene responsible for xylem loading of Si in rice. Fine mapping of this gene is being undertaken.
