Metabolic engineering of 2-phenylethanol pathway producing fragrance chemical and reducing lignin in Arabidopsis

Abstract

Key message 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. Abstract 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.

CYP79D73 Participates in Biosynthesis of Floral Scent Compound 2-Phenylethanol in Plumeria rubra

“…In plants, 2PE is synthesized in two major steps: (1) conversion of L-Phe into 2-phenylacetaldehyde (PAld) followed by (2) subsequent conversion of PAld into 2PE (Qi et al, 2015). Although few genes and pathways have been identified for the first step, only a single enzyme, phenylacetaldehyde reductase (PAR), is known to convert PAld to 2PE (Tieman et al, 2007;Chen et al, 2011).…”

Strategies for the production of biochemicals in bioenergy crops

“…2-PE accumulated as a glucoside form that was readily extractable using methyl tertbutyl ether as solvent [50]. Interestingly, a similar work conducted in Arabidopsis showed reduction of lignin content and improved biomass saccharification in addition to 2-PE production in engineered lines co-expressing PAR and PAAS genes [51]. Therefore, the approach may have the potential to reduce biomass recalcitrance for production of simple sugars in combination with the delivery of a valuable coproduct.…”

Wood forming tissue-specific expression of PdSuSy and HCHL increases holocellulose content and improves saccharification in Populus

“…The PdSuSy and HCHL coding regions were ligated to the Gateway entry vector pGWC-T and pEN-L4-2-L3 (Invitrogen, Thermo Fisher Scientific, Waltham MA, USA), respectively, and then transferred into the Gateway binary vector pK7m34GW2-8m21GW3 downstream of the AtCesA7 and AtC4H promoters ( Fig. 1a) following the method described previously (Qi et al 2015). After sequence validation, the resulting construct was introduced into 'nanlin895' via the leaf disc method (Chai et al 2014).…”