Biology subjects

Knosp, S.

Publications and source records attributed to Knosp, S..

3 recordsLinked to original sources

bioRxiv2026

The CUTIN SYNTHASE enzyme family was a key driver of cuticle emergence in land plants

The plant cuticle is a key adaptation acquired during the colonization of land. It forms a hydrophobic barrier at the interface with the environment, fulfilling essential protective and developmental functions. Despite its evolutionary significance and central role in land plant biology, the determinants that drove the emergence of the cuticle remain poorly understood. Here, we show that the CUTIN SYNTHASE (CUS) enzyme family, which synthesises the lipidic polyester that forms the structural framework of the cuticle in flowering plants, originated in a common ancestor of land plants, concomitant with terrestrialization. Using the moss Physcomitrium patens, we further demonstrate that CUS function is conserved among land plants. Inactivation of CUS genes disrupts gametophore development, the first tissue forming a cuticle during the moss life cycle, and compromises cuticle integrity. We also show that P. patens CUS enzymes localize to the apoplast, where they mediate the formation of a 10,16-dihydroxyhexadecanoic acid polyester using 2-mono-(10,16-dihydroxyhexadecanoyl)glycerol as substrate. Overall, our results reveal the conservation of CUS catalytic and physiological functions over 500 million years and support a pivotal role for this enzyme family in the emergence of the cuticle in an ancestral land plant during terrestrialization. SIGNIFICANCEThe cuticle is a hallmark of land plants that fulfills essential roles, ranging from protection to development. Elucidating the mechanisms underlying its emergence and formation therefore has the potential to reveal fundamental aspects of land plant evolution and biology. Here, we show that the CUTIN SYNTHASE (CUS) enzyme family, which catalyzes the formation of the cuticle framework in flowering plants, arose in an ancestor of land plants during terrestrialization. Using the moss Physcomitrium patens, we further demonstrate that CUS function has been conserved for 500 million years across bryophytes and tracheophytes. We propose that the emergence of the CUS family was a key event in establishing the plant cuticle during terrestrialization.

plant biology↗

bioRxiv2023

An ancient role for the CYP73 gene family in t-cinnamic acid 4-hydroxylation, phenylpropanoid biosynthesis and embryophyte development

The phenylpropanoid pathway is a plant metabolism intimately linked to the transition to terrestrial life. It produces phenolic compounds that play essential roles in stress mitigation and ecological interactions. The pathway also provides the building blocks for hydrophobic polymers that form apoplastic diffusion barriers and make up a significant fraction of the land plant biomass. Despite its significance in embryophytes (i.e., land plants), the origin and evolutionary history of the phenylpropanoid pathway remain poorly understood. In particular, little is known about the organization and function of the pathway in bryophytes, the non-vascular embryophytes. In this study, we conducted a multidisciplinary analysis of the CYP73 gene family that encodes t-cinnamic acid 4-hydroxylase (C4H), the first plant-specific enzyme in the pathway. Our results indicate that C4H activity originated with the emergence of the CYP73 gene family in an ancestor of land plants and was supported by an arginine residue that stabilizes its substrate in the active site. C4H deficiency in the moss Physcomitrium patens, the liverwort Marchantia polymorpha and the hornwort Anthoceros agrestis resulted in a shortage of phenylpropanoids and abnormal plant development. The latter could be rescued in the moss by the exogenous supply of p-coumaric acid, the product of C4H. Our findings establish the emergence of the CYP73 gene family as a foundational event for the development of the canonical plant phenylpropanoid pathway and underscores the deep-rooted conservation of the C4H enzyme function in embryophyte biology.

plant biology↗

bioRxiv2020

Function of the HYDROXYCINNAMOYL-CoA:SHIKIMATE HYDROXYCINNAMOYL TRANSFERASE is evolutionarily conserved in embryophytes

The plant phenylpropanoid pathway generates a major class of specialized metabolites and precursors of essential extracellular polymers that initially appeared upon plant terrestrialization. Despite its evolutionary significance, little is known about the complexity and function of this major metabolic pathway in extant bryophytes, which represent the non-vascular stage of embryophyte evolution. Here, we report that the HYDROXYCINNAMOYL-CoA:SHIKIMATE HYDROXYCINNAMOYL TRANSFERASE (HCT) gene that plays a critical function in the phenylpropanoid pathway during seed plant development, is functionally conserved in Physcomitrium patens (Physcomitrella), in the moss lineage of bryophytes. Phylogenetic analysis indicates that bonafide HCT function emerged in the progenitor of embryophytes. In vitro enzyme assays, moss phenolic pathway reconstitution in yeast and in planta gene inactivation coupled to targeted metabolic profiling, collectively indicate that P. patens HCT (PpHCT), similar to tracheophyte HCT orthologs, uses shikimate as a native acyl acceptor to produce a p-coumaroyl-5-O-shikimate intermediate. Phenotypic and metabolic analyses of loss-of-function mutants show that PpHCT is necessary for the production of caffeate derivatives, including previously reported caffeoyl-threonate esters, and for the formation of an intact cuticle. Deep conservation of HCT function in embryophytes is further suggested by the ability of HCT genes from P. patens and the liverwort Marchantia polymorpha to complement an Arabidopsis thaliana CRISPR/Cas9 hct mutant, and by the presence of phenolic esters of shikimate in representative species of the three bryophyte lineages.

plant biology↗