Biomass and Bioenergy Research Centre, Huazhong Agricultural University, Wuhan, China.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
Sci Rep. 2018 Feb 26;8(1):3636. doi: 10.1038/s41598-018-21741-y.
Lignin content and composition are crucial factors affecting biomass digestibility. Exploring the genetic loci simultaneously affecting lignin-relevant traits and biomass digestibility is a precondition for lignin genetic manipulation towards energy crop breeding. In this study, a high-throughput platform was employed to assay the lignin content, lignin composition and biomass enzymatic digestibility of a rice recombinant inbred line population. Correlation analysis indicated that the absolute content of lignin monomers rather than lignin content had negative effects on biomass saccharification, whereas the relative content of p-hydroxyphenyl unit and the molar ratio of p-hydroxyphenyl unit to guaiacyl unit exhibited positive roles. Eight QTL clusters were identified and four of them affecting both lignin composition and biomass digestibility. The additive effects of clustered QTL revealed consistent relationships between lignin-relevant traits and biomass digestibility. Pyramiding rice lines containing the above four positive alleles for increasing biomass digestibility were selected and showed comparable lignin content, decreased syringyl or guaiacyl unit and increased molar percentage of p-hydroxyphenyl unit, the molar ratio of p-hydroxyphenyl unit to guaiacyl unit and sugar releases. More importantly, the lodging resistance and eating/cooking quality of pyramiding lines were not sacrificed, indicating the QTL information could be applied to select desirable energy rice lines.
木质素含量和组成是影响生物质消化率的关键因素。探索同时影响木质素相关性状和生物质消化率的遗传位点，是进行木质素遗传操作以培育能源作物的前提。本研究利用高通量平台对水稻重组自交系群体的木质素含量、木质素组成和生物质酶解活性进行了测定。相关性分析表明，木质素单体的绝对含量而不是木质素含量对生物质糖化有负面影响，而对羟苯基单元的相对含量和对羟苯基单元与愈创木基单元的摩尔比则表现出积极作用。鉴定出 8 个 QTL 簇，其中 4 个同时影响木质素组成和生物质消化率。聚类 QTL 的加性效应揭示了木质素相关性状与生物质消化率之间的一致关系。选择含有上述四个增加生物质消化率的正效等位基因的水稻系进行聚合，表现出可比的木质素含量、降低的丁香基或愈创木基单元以及增加的对羟苯基单元的摩尔百分比、对羟苯基单元与愈创木基单元的摩尔比和糖的释放。更重要的是，聚合系的抗倒伏性和食用/烹饪品质没有受到影响，表明 QTL 信息可用于选择理想的能源稻系。
