Identification of gamma irradiated Brachypodium mutants with altered genes responsible for lignin biosynthesis

Brachypodium distachyon (Brachypodium) is a novel model plant for structural and functional genomic studies of Poaceae. Brachypodium has many favorable features, such as small size, small genome, short life cycle, and easy handling. Bioethanol, as renewable resource, has been widely studied as a replacement for fossil fuels. Lignin is involved with the efficiency of energy feedstock. It is generally accepted that bioethanol production is negatively affected by lignin content. Brachypodium was irradiated with gamma irradiation, at doses of 50, 100, 150, 200, and 250 Gy, and 25 M₂ plants that showed the least staining with phloroglucinol were selected. Nucleotide alteration within genes that contribute to the lignin biosynthesis pathway was analyzed. In total, 4 INDELs and 249 SNPs which included 2 additional nonsense mutations, a mutation at the start codon, and a mutation at the 3′ splicing site were identified in the M₂ lines. The transition/transversion rate was 7.59, and single nucleotide substitutions were found every 1,143 bp. As biological resources, the M₂ populations generated in this work will contribute to functional genomics of Brachypodium and to the breeding of grass crops.