Highlights•New monomers have been discovered, and structural aspects of the lignin
polymer have been refined.•The definition of a lignin monomer has been broadened.• …

Highlights•Hemicelluloses can interact with lignin through covalent cross-links in plant cell
walls.•Different reaction mechanisms can lead to cross-linking using diverse hemicellulose …

Replacing fossil-based resources with renewable alternatives is generally acknowledged as
a critical component to address several of today's environmental concerns. In this context …

Aromatic amino acid deaminases are key enzymes mediating carbon flux from primary to
secondary metabolism in plants. Recent studies have uncovered a tyrosine ammonia-lyase …

Plants represent a vast, renewable resource and are well suited to provide sustainably for
humankind's transportation fuel needs. To produce infrastructure-compatible fuels from …

Millets rank six in the world cereal grain production. In Africa and Asia, these underutilized
grains play a major role in the food security of millions of people. In addition to being a rich …

Lignins are complex natural polymers resulting from oxidative coupling of, primarily, 4-
hydroxyphenylpropanoids. An understanding of their nature is evolving as a result of …

The chemical complexity of lignin remains a major challenge for lignin valorization into
commodity and fine chemicals. A knowledge of the lignin features that favor its valorization …

Covering: Up to 2019 Phenolic cross-links and phenolic inter-unit linkages result from the
oxidative coupling of two hydroxycinnamates or two molecules of tyrosine. Free dimers of …

Lignin, a phenolic polymer in the secondary wall, is the major cause of lignocellulosic
biomass recalcitrance to efficient industrial processing. From an applications perspective, it …