Designing biomass lignins for the biorefinery

4 páginas.- 3 figuras. 17 referencias.- Comunicación oral presentada en el 16th European Workshop on Lignocellulosics and Pulp (EWLP) Gothenburg, Sweden, June 28 – July 1, 2022As ever more component monomers are discovered, lignin can no longer be regarded as deriving from just the three canonical monolignols. Pathway intermediates and additional products of truncated biosynthesis are now established lignin monomers. The array of acylated monolignols continues to expand. Game-changing findings have demonstrated that phenolics from alternative pathways, including flavonoids and hydroxystilbenes, are also involved in lignification, expanding the traditional concept. Beyond the basic science intrigue, these findings propound exciting new avenues for valorizing lignins, or for producing more readily extractable or depolymerizable lignins, in crop and bioenergy plants.We further acknowledge lots of colleagues and collaborators, and funding from the Swiss National Science Foundation (Synergia) grant # CRS115_180258, and the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-SC0018409).N

Stability of Plant Defense Proteins in the Gut of Insect Herbivores

Plant defense against insect herbivores is mediated in part by enzymes that impair digestive processes in the insect gut. Little is known about the evolutionary origins of these enzymes, their distribution in the plant kingdom, or the mechanisms by which they act in the protease-rich environment of the animal digestive tract. One example of such an enzyme is threonine (Thr) deaminase (TD), which in tomato (Solanum lycopersicum) serves a dual role in isoleucine (Ile) biosynthesis in planta and Thr degradation in the insect midgut. Here, we report that tomato uses different TD isozymes to perform these functions. Whereas the constitutively expressed TD1 has a housekeeping role in Ile biosynthesis, expression of TD2 in leaves is activated by the jasmonate signaling pathway in response to herbivore attack. Ingestion of tomato foliage by specialist (Manduca sexta) and generalist (Trichoplusia ni) insect herbivores triggered proteolytic removal of TD2's C-terminal regulatory domain, resulting in an enzyme that degrades Thr without being inhibited through feedback by Ile. This processed form (pTD2) of TD2 accumulated to high levels in the insect midgut and feces (frass). Purified pTD2 exhibited biochemical properties that are consistent with a postingestive role in defense. Shotgun proteomic analysis of frass from tomato-reared M. sexta identified pTD2 as one of the most abundant proteins in the excrement. Among the other tomato proteins identified were several jasmonate-inducible proteins that have a known or proposed role in anti-insect defense. Subtilisin-like proteases and other pathogenesis-related proteins, as well as proteins of unknown function, were also cataloged. We conclude that proteomic analysis of frass from insect herbivores provides a robust experimental approach to identify hyperstable plant proteins that serve important roles in defense

Monolignol ferulate transferase introduces chemically labile linkages into the lignin backbone

4 páginas.-- 4 figuras.-- 1 tabla.-- 27 referncias.--- El pdf. del Material Suplementarío tiene 29 páginas. Contiene: Materials and Methods.-- Supplementary Text.-- Figs. S1 to S9.-- Tables S1 to S4.-- 39 ReferencesRedesigning lignin, the aromatic polymer fortifying plant cell walls, to be more amenable to chemical depolymerization can lower the energy required for industrial processing. We have engineered poplar trees to introduce ester linkages into the lignin polymer backbone by augmenting the monomer pool with monolignol ferulate conjugates. Herein, we describe the isolation of a transferase gene capable of forming these conjugates and its xylem-specific introduction into poplar. Enzyme kinetics, in planta expression, lignin structural analysis, and improved cell wall digestibility after mild alkaline pretreatment demonstrate that these trees produce the monolignol ferulate conjugates, export them to the wall, and use them during lignification. Tailoring plants to use such conjugates during cell wall biosynthesis is a promising way to produce plants that are designed for deconstruction.Peer reviewe