Identifying lignocellulose recalcitrant factors and exploring their genetic properties are essential for enhanced biomass enzymatic saccharification in bioenergy crops. Despite genetic modification of major wall polymers has been implemented for reduced recalcitrance in engineered crops, it could most cause a penalty of plant growth and biomass yield. Alternatively, it is increasingly considered to improve minor wall components, but an applicable approach is required for efficient assay of large population of biomass samples. Hence, this study collected total of 100 rice straw samples and characterized all minor wall monosaccharides and biomass enzymatic saccharification by integrating NIRS modeling and QTL profiling. By performing classic chemical analyses and establishing optimal NIRS equations, this study examined four minor wall monosaccharides and major wall polymers (acid-soluble lignin/ASL, acid-insoluble lignin/AIL, three lignin monomers, crystalline cellulose), which led to largely varied hexoses yields achieved from enzymatic hydrolyses after two alkali pretreatments were conducted with large population of rice straws. Correlation analyses indicated that mannose and galactose can play a contrast role for biomass enzymatic saccharification at P < 0.0 l level (n = 100). Meanwhile, we found that the QTLs controlling mannose, galactose, lignin-related traits, and biomass saccharification were co-located. By combining NIRS assay with QTLs maps, this study further interpreted that the mannose-rich hemicellulose may assist AIL disassociation for enhanced biomass enzymatic saccharification, whereas the galactose-rich polysaccharides should be effectively extracted with ASL from the alkali pretreatment for condensed AIL association with cellulose microfibrils. By integrating NIRS assay with QTL profiling for large population of rice straw samples, this study has identified that the mannose content of wall polysaccharides could positively affect biomass enzymatic saccharification, while the galactose had a significantly negative impact. It has also sorted out that two minor monosaccharides could distinctively associate with lignin deposition for wall network construction. Hence, this study demonstrates an applicable approach for fast assessments of minor lignocellulose recalcitrant factors and biomass enzymatic saccharification in rice, providing a potential strategy for bioenergy crop breeding and biomass processing.

中文翻译：

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综合 NIRS 和 QTL 分析揭示了微量甘露糖和半乳糖作为水稻生物质酶糖化的对比木质纤维素因子

识别木质纤维素顽固因子并探索其遗传特性对于增强生物能源作物中的生物质酶糖化至关重要。尽管已经实施了主要壁聚合物的遗传修饰以减少工程作物的顽固性，但它最可能导致植物生长和生物量产量的损失。或者，人们越来越多地考虑改进小壁组件，但需要一种适用的方法来有效分析大量生物质样品。因此，本研究收集了总共 100 个稻草样品，并通过整合 NIRS 建模和 QTL 分析来表征所有小壁单糖和生物质酶促糖化。通过执行经典化学分析并建立最佳近红外光谱方程，这项研究检查了四种小壁单糖和主壁聚合物（酸溶性木质素/ASL、酸不溶性木质素/AIL、三种木质素单体、结晶纤维素），这导致在两次碱预处理后酶促水解产生的己糖产量差异很大。用大量稻草进行。相关性分析表明，甘露糖和半乳糖可以在 P < 0.0 l 水平（n = 100）的生物质酶糖化中起对比作用。同时，我们发现控制甘露糖、半乳糖、木质素相关性状和生物量糖化的 QTL 是共存的。通过将 NIRS 检测与 QTL 图相结合，该研究进一步解释了富含甘露糖的半纤维素可能有助于 AIL 解离以增强生物质酶糖化，而富含半乳糖的多糖应该用 ASL 从碱预处理中有效地提取出来，以将 AIL 与纤维素微纤丝结合。通过将 NIRS 测定与 QTL 分析相结合，对大量稻草样品进行分析，该研究确定壁多糖的甘露糖含量可以对生物质酶糖化产生积极影响，而半乳糖具有显着的负面影响。它还整理出两种次要的单糖可以与木质素沉积显着相关，用于壁网构建。因此，本研究展示了一种快速评估水稻中次要木质纤维素顽固因子和生物质酶糖化的适用方法，为生物能源作物育种和生物质加工提供了潜在的策略。