Ko Hirano1, Reiko Masuda2, Wakana Takase2, Yoichi Morinaka2,3, Mayuko Kawamura2, Yoshinobu Takeuchi4, Hiroki Takagi5, Hiroki Yaegashi5, Satoshi Natsume5, Ryohei Terauchi5, Toshihisa Kotake6,7, Yasuyuki Matsushita8, Takashi Sazuka2. 1. Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi, 464-8601, Japan. khirano@nuagr1.agr.nagoya-u.ac.jp. 2. Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi, 464-8601, Japan. 3. Zensho Holdings Co., Ltd., Tokyo, Japan. 4. Rice Breeding Research Team, NARO Institute of Crop Science, Tsukuba, Ibaraki, Japan. 5. Iwate Biotechnology Research Center, Kitakami, Iwate, Japan. 6. Graduate School of Science and Engineering, Saitama University, Saitama, Japan. 7. Institute for Environmental Science and Technology, Saitama University, Saitama, Japan. 8. Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan.
Abstract
MAIN CONCLUSION: The screening of rice mutants with improved cellulose to glucose saccharification efficiency (SE) identifies reduced xylan and/or ferulic acid, and a qualitative change of lignin to impact SE. To ensure the availability of sustainable energy, considerable effort is underway to utilize lignocellulosic plant biomass as feedstock for the production of biofuels. However, the high cost of degrading plant cell wall components to fermentable sugars (saccharification) has been problematic. One way to overcome this barrier is to develop plants possessing cell walls that are amenable to saccharification. In this study, we aimed to identify new molecular factors that influence saccharification efficiency (SE) in rice. By screening 22 rice mutants, we identified two lines, 122 and 108, with improved SE. Reduced xylan and ferulic acid within the cell wall of line 122 were probable reasons of improved SE. Line 108 showed reduced levels of thioglycolic-released lignin; however, the amount of Klason lignin was comparable to the wild-type, indicating that structural changes had occurred in the 108 lignin polymer which resulted in improved SE. Positional cloning revealed that the genes responsible for improved SE in 122 and 108 were rice CONSTITUTIVE PHOTOMORPHOGENIC 1 (OsCOP1) and GOLD HULL AND INTERNODE 1 (GH1), respectively, which have not been previously reported to influence SE. The screening of mutants for improved SE is an efficient approach to identify novel genes that affect SE, which is relevant in the development of crops as biofuel sources.
MAIN CONCLUSION: The screening of rice mutants with improved cellulose to glucose saccharification efficiency (SE) identifies reduced xylan and/or ferulic acid, and a qualitative change of lignin to impact SE. To ensure the availability of sustainable energy, considerable effort is underway to utilize lignocellulosic plant biomass as feedstock for the production of biofuels. However, the high cost of degrading plant cell wall components to fermentable sugars (saccharification) has been problematic. One way to overcome this barrier is to develop plants possessing cell walls that are amenable to saccharification. In this study, we aimed to identify new molecular factors that influence saccharification efficiency (SE) in rice. By screening 22 rice mutants, we identified two lines, 122 and 108, with improved SE. Reduced xylan and ferulic acid within the cell wall of line 122 were probable reasons of improved SE. Line 108 showed reduced levels of thioglycolic-released lignin; however, the amount of Klason lignin was comparable to the wild-type, indicating that structural changes had occurred in the 108 lignin polymer which resulted in improved SE. Positional cloning revealed that the genes responsible for improved SE in 122 and 108 were rice CONSTITUTIVE PHOTOMORPHOGENIC 1 (OsCOP1) and GOLD HULL AND INTERNODE 1 (GH1), respectively, which have not been previously reported to influence SE. The screening of mutants for improved SE is an efficient approach to identify novel genes that affect SE, which is relevant in the development of crops as biofuel sources.
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Authors: Wagner R de Souza; Polyana K Martins; Jackie Freeman; Till K Pellny; Louise V Michaelson; Bruno L Sampaio; Felipe Vinecky; Ana P Ribeiro; Barbara A D B da Cunha; Adilson K Kobayashi; Patricia A de Oliveira; Raquel B Campanha; Thályta F Pacheco; Danielly C I Martarello; Rogério Marchiosi; Osvaldo Ferrarese-Filho; Wanderley D Dos Santos; Robson Tramontina; Fabio M Squina; Danilo C Centeno; Marília Gaspar; Marcia R Braga; Marco A S Tiné; John Ralph; Rowan A C Mitchell; Hugo B C Molinari Journal: New Phytol Date: 2018-01-08 Impact factor: 10.151