title: Metabolic engineering of 2-phenylethanol pathway producing fragrance chemical and reducing lignin in Arabidopsis.
abstract: Two 2-phenylethanol biosynthetic pathways were constructed into Arabidopsis ; 2-phenylethanol biosynthesis led to reduced rate of lignin biosynthesis and increased cellulose-to-glucose conversion in the transgenic plants. Lignin is the second most abundant biopolymer on the planet with importance for various agro-industrial activities. The presence of lignin in cell walls, however, impedes biofuel production from lignocellulosic biomass. The phenylpropanoid pathway is responsible for the biosynthesis of lignin and other phenolic metabolites such as 2-phenylethanol. As one of the most used fragrance chemicals, 2-phenylethanol is synthesized in plants from L-phenylalanine which is the first specific intermediate towards lignin biosynthesis. Thus, it is interesting to prove the concept that the phenylpropanoid pathway can be modulated for reduction of lignin as well as production of natural value-added compounds. Here we conferred two 2-phenylethanol biosynthetic pathways constructed from plants and Saccharomyces cerevisiae into Arabidopsis. As anticipated, 2-phenylethanol was accumulated in transgenic plants. Moreover, the transformants showed 12-14% reduction in lignin content and 9-13% increase in cellulose content. Consequently, the glucose yield from cell wall hydrolysis was increased from 37.4% in wild type to 49.9-52.1% in transgenic plants with hot water pretreatment. The transgenic plants had normal development and even enhanced growth relative to the wild type. Our results indicate that the shunt of L-phenylalanine flux to the artificially constructed 2-phenylethanol biosynthetic pathway most likely reduced the rate of lignin biosynthesis in Arabidopsis.
authors.affiliation: Key Laboratory of Biofuels and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China, qiguang@qibebt.ac.cn.
authors.forename: Guang
authors.initials: G
authors.lastname: Qi
authors.forename: Dian
authors.initials: D
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Tang
authors.forename: Guohua
authors.initials: G
authors.lastname: Chai
authors.forename: Guo
authors.initials: G
authors.lastname: He
authors.forename: Wenxuan
authors.initials: W
authors.lastname: Ma
authors.forename: Shengying
authors.initials: S
authors.lastname: Li
authors.forename: Yingzhen
authors.initials: Y
authors.lastname: Kong
authors.forename: Chunxiang
authors.initials: C
authors.lastname: Fu
authors.forename: Gongke
authors.initials: G
authors.lastname: Zhou
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000737:chemistry; D002482:Cellulose / Q000032:analysis; D005818:Genetic Engineering / Q000379:methods; D008031:Lignin / Q000032:analysis / Q000096:biosynthesis*; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D032306:Petunia / Q000235:genetics / Q000378:metabolism; D010626:Phenylethyl Alcohol / Q000032:analysis / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism
chemical_list: D011134:Polysaccharides; D002482:Cellulose; D008031:Lignin; D010626:Phenylethyl Alcohol