Identification of lignin-deficient brachypodium distachyon (L.) beauv. mutants induced by gamma radiation

BACKGROUND: Brachypodium distachyon (L.) Beauv. is a monocotyledonous model plant that has been studied to understand a range of biological phenomena for lignocellulosic bioethanol feedstocks and other cereal crops. The lignin makes its cell walls recalcitrant to saccharification, constituting the main barrier to lignocellulosic bioethanol production. In this study, lignin-deficient mutants of B. distachyon induced by chronic radiation were selected and the effects of the mutants on fermentable glucose production were identified. RESULTS: Brachypodium distachyon M₂ mutants induced by chronically irradiated gamma radiation were screened by the Wiesner test. Lignin-deficient M₂ mutants were further confirmed in subsequent M₃ and M₄ generations by determining acetyl bromide-soluble lignin. The lignin content was significantly reduced in mutant plants 135-2 (by 7.99%), 142-3 (by 13.8%) and 406-1 (by 8.13%) comparedwith the wild type. Moreover, fermentable glucosewas significantly higher in 135-2 (by 23.91%) and 142-3 (by 36.72%) than in the wild type after 72 h of enzymatic hydrolysis. CONCLUSION: Three lignin-deficient B. distachyon mutants induced by chronically irradiated gamma radiation were obtained. This study will provide fundamental understanding of the B. distachyon cellwall and could contribute to increases in bioethanol production using bioenergy crops.