Altered lignocellulose chemical structure and molecular assembly in CINNAMYL ALCOHOL DEHYDROGENASE-deficient rice

Lignin is a complex phenylpropanoid polymer deposited in plant cell walls. Lignin has long been recognized as an important limiting factor for the polysaccharide-oriented biomass utilizations. To mitigate lignin-associated biomass recalcitrance, numerous mutants and transgenic plants that produce lignocellulose with reduced lignin contents and/or lignins with altered chemical structures have been produced and characterised. However, it is not fully understood how altered lignin chemistry affects the supramolecular structure of lignocellulose, and consequently, its utilization properties. Herein, we conducted comprehensive chemical and supramolecular structural analyses of lignocellulose produced by a rice cad2 mutant deficient in CINNAMYL ALCOHOL DEHYDROGENASE (CAD), which encodes a key enzyme in lignin biosynthesis. By using a solution-state two-dimensional NMR approach and complementary chemical methods, we elucidated the structural details of the altered lignins enriched with unusual hydroxycinnamaldehyde-derived substructures produced by the cad2 mutant. In parallel, polysaccharide assembly and the molecular mobility of lignocellulose were investigated by solid-state 13C MAS NMR, nuclear magnetic relaxation, X-ray diffraction, and Simon’s staining analyses. Possible links between CAD-associated lignin modifications (in terms of total content and chemical structures) and changes to the lignocellulose supramolecular structure are discussed in the context of the improved biomass saccharification efficiency of the cad2 rice mutant

リグニンを改変したイネ変異体におけるリグノセルロースの超分子構造と分解特性に関する研究

京都大学0048新制・課程博士博士(農学)甲第22502号農博第2406号新制||農||1077(附属図書館)学位論文||R2||N5282(農学部図書室)京都大学大学院農学研究科応用生命科学専攻(主査)教授 梅澤 俊明, 教授 矢﨑 一史, 教授 渡邊 隆司学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDGA

PRODUCTION OF MALTOOLIGOSACCHARIDES FROM HUTAN JATI VARIETY CULTIVAR TACCA (Tacca leontopetaloides) STARCH

This research aimed to extract and characterize the physicochemical properties of starch from Tacca tuber, to determine the optimum conditions for enzymatic hydrolysis to produce maltooligosaccharides, and to analyze the character of these maltooligosaccharides. The analysis was conducted by calculating the amount of reducing sugar, total sugar, and the degree of polymerization, and by using the TLC (Thin Layer Chromatography) and HPLC (High-Performance Liquid Chromatography) analyses. The Hutan Jati variety cultivar of Tacca was selected from three Tacca variety cultivars (Hutan Jati, Pulau Katang and Gunung Batur) to produce maltooligosaccharides by enzymatic hydrolysis of crude Brevibacterium sp. α-amylase. The optimum conditions for the enzymatic hydrolysis of Hutan Jati variety cultivar Tacca starch for the production of maltooligosaccharides were obtained at a substrate concentration of 3% (w/v) and a ratio of 1:5 enzyme and substrate at 6 hours incubation time. From 250 mL of fresh hydrolysate, some 34.49 grams of powder maltooligosaccharide were produced. The TLC and HPLC results showed a similar yield of both the liquid and powder maltooligosaccharides with maltose, maltotriose, and maltotetraose as the main products. Considering its physicochemical characteristics and the product of its maltooligosaccharides, the starch from the tuber of Hutan Jati variety cultivar Tacca possessed strong potential for the future production of maltooligosaccharides particularly,  maltotriose and maltotetraose, in food industries

Altered lignocellulose chemical structure and molecular assembly in CINNAMYL ALCOHOL DEHYDROGENASE-deficient rice

Lignin is a complex phenylpropanoid polymer deposited in plant cell walls. Lignin has long been recognized as an important limiting factor for the polysaccharide-oriented biomass utilizations. To mitigate lignin-associated biomass recalcitrance, numerous mutants and transgenic plants that produce lignocellulose with reduced lignin contents and/or lignins with altered chemical structures have been produced and characterised. However, it is not fully understood how altered lignin chemistry affects the supramolecular structure of lignocellulose, and consequently, its utilization properties. Herein, we conducted comprehensive chemical and supramolecular structural analyses of lignocellulose produced by a rice cad2 mutant deficient in CINNAMYL ALCOHOL DEHYDROGENASE (CAD), which encodes a key enzyme in lignin biosynthesis. By using a solution-state two-dimensional NMR approach and complementary chemical methods, we elucidated the structural details of the altered lignins enriched with unusual hydroxycinnamaldehyde-derived substructures produced by the cad2 mutant. In parallel, polysaccharide assembly and the molecular mobility of lignocellulose were investigated by solid-state 13C MAS NMR, nuclear magnetic relaxation, X-ray diffraction, and Simon’s staining analyses. Possible links between CAD-associated lignin modifications (in terms of total content and chemical structures) and changes to the lignocellulose supramolecular structure are discussed in the context of the improved biomass saccharification efficiency of the cad2 rice mutant

Elicitation of Secondary Metabolites in <i>Aquilaria malaccensis</i> Lam. Callus Culture by Crude Mycelial Extract of <i>Fusarium solani</i> and Methyl Jasmonate

Agarwood is a resinous wood of great economic value produced by trees from the Thymelaeaceae family in response to stress. The natural formation of agarwood can take decades after exposure to the stressors. Artificial agarwood induction by inoculating the stem with fungi has been successfully demonstrated, but resin accumulation occurs very slowly. Cell suspension and callus cultures may serve as an alternative solution to provide a fast-growing plant material to produce artificial agarwood in a short period. Here, we induced agarwood formation in callus cultures of Aquilaria malaccensis by application of crude mycelial extracts of Fusarium solani strains GSL1 or GSL2, or methyl jasmonate (MeJA). After 20 days of treatment with elicitors, all treated calluses had less dry weight than the control group. The gas chromatography–mass spectrometry analysis identified 33 different secondary metabolites among all samples, four of which were present in all treatments and control, i.e., 1-docosene and 1-octadecene (alkenes), 4-di-tert-buthylphenol (phenolic), and benzenepropanoic acid (fatty acid). The 6-methoxy-2-(4-methoxyphenethyl)-4H-chromene-4-one, a chromone derivative, was only detected in callus elicited with the F. solani strain GSL2 and MeJA. All treated calli produced more fatty acid derivatives than the control group. We conclude that elicitors used in this study can induce the production of agarwood-related chemicals such as chromone and fatty acid in callus culture