Silencing CAFFEOYL SHIKIMATE ESTERASE Affects Lignification and Improves Saccharification in Poplar

Author(s):Show less -

Soriano Saleme, Marina De Lyra ^{[1, 2]} ; Cesarino, Igor ^{[1, 2, 3]} ; Vargas, Livia ^{[1, 2]} ; Kim, Hoon ^{[4, 5]} ; Vanholme, Ruben ^{[1, 2]} ; Goeminne, Geert ^{[1, 2]} ; Van Acker, Rebecca ^{[1, 2]} ; de Assis Fonseca, Fernando Campos ^{[1, 2]} ; Pallidis, Andreas ^{[1, 2]} ; Voorend, Wannes ^{[1, 2]} ; Nicomedes Junior, Jose ^{[1, 2, 6]} ; Padmakshan, Dharshana ^{[4, 5]} ; Van Doorsselaere, Jan ^[7] ; Ralph, John ^{[4, 5]} ; Boerjan, Wout ^{[1, 2]}

Affiliation

^[1] Univ Ghent, Dept Plant Biotechnol & Bioinformat, B-9052 Ghent - Belgium

^[2] VIB Ctr Plant Syst Biol, B-9052 Ghent - Belgium

^[3] Univ Sao Paulo, Inst Biosci, Dept Bot, BR-05508090 Butanta, SP - Brazil

^[4] Univ Wisconsin, Wisconsin Energy Inst, Dept Energy Great Lakes Bioenergy Res Ctr, Madison, WI 53726 - USA

^[5] Univ Wisconsin, Dept Biochem, Madison, WI 53706 - USA

^[6] Petroleo Brasileiro SA, Ctr Pesquisas Leopoldo Amer Miguez de Mello, BR-21941598 Rio De Janeiro - Brazil

^[7] VIVES, B-8800 Roeselare - Belgium

• Document type: Journal article
• Source: Plant Physiology; v. 175, n. 3, p. 1040-1057, NOV 2017.
• Web of Science Citations: 22

Abstract

Caffeoyl shikimate esterase (CSE) was recently shown to play an essential role in lignin biosynthesis in Arabidopsis (Arabidopsis thaliana) and later in Medicago truncatula. However, the general function of this enzyme was recently questioned by the apparent lack of CSE activity in lignifying tissues of different plant species. Here, we show that down-regulation of CSE in hybrid poplar (Populus tremula x Populus alba) resulted in up to 25% reduced lignin deposition, increased levels of p-hydroxyphenyl units in the lignin polymer, and a relatively higher cellulose content. The transgenic trees were morphologically indistinguishable from the wild type. Ultra-high-performance liquid chromatography-mass spectrometry-based phenolic profiling revealed a reduced abundance of several oligolignols containing guaiacyl and syringyl units and their corresponding hydroxycinnamaldehyde units, in agreement with the reduced flux toward coniferyl and sinapyl alcohol. These trees accumulated the CSE substrate caffeoyl shikimate along with other compounds belonging to the metabolic classes of benzenoids and hydroxycinnamates. Furthermore, the reduced lignin amount combined with the relative increase in cellulose content in the CSE down-regulated lines resulted in up to 62% more glucose released per plant upon limited saccharification when no pretreatment was applied and by up to 86% and 91% when acid and alkaline pretreatments were used. Our results show that CSE is not only important for the lignification process in poplar but is also a promising target for the development of improved lignocellulosic biomass crops for sugar platform biorefineries. (AU)

• FAPESP's process: 15/02527-1 - Development of model systems in sorghum and a systems biology approach to unravel the molecular mechanisms controlling lignin metabolism in grasses
• Grantee: Igor Cesarino
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants