Rice, as a model system of monocotyledon plants for genomic studies, is a main staple food for over half of the world population. A rice retrotransposon, Tos17, is active during tissue culture and its ability was wildly used in insertional mutagenesis. In this study we have produced 2,000 non-GM mutants induced by Tos17 in rice. We analyzed >2,000 flanking sequences of newly transposed Tos17 copies by the adaptor-ligation PCR method. The frequencies of Tos17 insertions in the genic and intergenic regions were 60.3% and 36.6%, respectively. We also selected four Tos17 insertion mutant lines for three TF genes which can be considered to be considered to be involved in rice seed development based on expression microarray data: osrem3, osta1, osbhlh1-1, and osbhlh1-2 mutant lines. According to Quadruple 9-mer-based protein binding microarray (Q9-UPBM) experiment, we found that the OsREM3, OsTA1, and OsbHLH1 bound to the ACACCAC, CACGTG, and GTAACA motifs, respectively. In combination of Q9-UPBM, RiceArrayNet analysis, and expression microarray data, we identified 8, 20, and 9 putative target genes of OsREM3, OsTA1, and OsbHLH1, respectively. We have been screening and characterizing the mutations by extensive phenotypic analysis as well as the functional analysis of genes.

Salt and drought stresses affect virtually every aspect of plant physiology and metabolism and thus limiting the productivity of crop plants worldwide. Salt and drought tolerance and adaptation in rice has been improved by engineering various genes related to transcription, signaling, accumulation of antioxidants and compatible solutes etc. Previously, we have produced 2,000 non-GM mutants induced by Tos17 in rice. We analyzed >2,000 flanking sequences of newly transposed Tos17 copies by the adaptor-ligation PCR method. We also identified significantly up- or down-regulated genes under drought, salt, or ABA stress in rice based on expression microarray data, which previously were performed from leaf at different developmental stages and conditions. For screening and characterizing the salt or drought tolerance mutations by extensive phenotypic analysis as well as the functional analysis of genes, we selected 133 mutant lines. To evaluate rice phenotypic traits under abiotic stress condition, we plan to investigate phenomics, which integrates technologies such as photonics, biology, computers, and robotics.