Brachypodium has been focused as new model plant for grass species. Like small size, small room requirement, and fast growth, Brachypodium shows numerous advantages as a model plant. Brachypodium is a typical grass at the genome level, which also exhibits an overall similarity of gene content and gene families when compared with rice (Oryza sativa) and sorghum (Sorghum bicolor) genomes. Brachypodium is an excellent material for structural and functional genomic studies in grass species. Targeting-Induced Local Lesions IN Genomes (TILLING) is a high-throughput technique and an approach for reverse genetics study. Moreover, it has been wildly utilized to find induced mutation. Bradi3g45515 is orthologue of the cellulose synthase-like HvCslF8 in barley. For TILLING library construction, 384 M2 Brachypodium mutants induced by chronic-gamma irradiation were used. Single nucleotide polymorphysm (SNP) and small deletion in Bradi3g45515 were searched through TILLING analysis. Template DNA for PCR reaction were prepared according to two dimensional pooling (eightfold) strategy. Heteroduplex DNA was digested by SURVEYOR nuclease (TRANSGENOMIC) and the DNA fragment was detected using polyacrylamide gel electrophoresis. Positive signal appeared at polyacrylamide gel from more than 4 lines and their Bradi3g45515 region were sequenced. SNP(s) were identified in 509-2 and 677-3 mutant line. Cellulose content and/or cell wall materials content will be measured using these mutants.