Biology subjects

Sorensen, I.

Publications and source records attributed to Sorensen, I..

4 recordsLinked to original sources

bioRxiv2025

Spatiotemporal variation in cutin polymerization and remodeling mediated by GDSL-hydrolase enzymes during tomato fruit development

Land plants produce a cuticle, an extracellular hydrophobic layer that covers aerial organs and is involved in many critical protective roles, most notably in preventing desiccation. The predominant component of the cuticle is the lipidic polyester, cutin, which is deposited in the epidermal primary cell wall. Most of cutin of tomato fruit, a model for cuticle research, is polymerized by the extracellular GDSL-hydrolase enzyme CUTIN SYNTHASE-LIKE 1 (CUS1). However, other enzymes involved in cutin assembly remain to be identified and characterized. In this current study, we investigated whether other GDSL-hydrolases that are highly expressed in fruit epidermis might also contribute to cutin polymerization and restructuring. Candidates include homologs of Arabidopsis thaliana CUTICLE DESTRUCTIVE FACTOR 1 (CDEF1), which has been reported to catalyze cutin hydrolysis, as well as other phylogenetically diverse and distantly related GDSL-hydrolases. We determined that members of the CUS and CDEF families can catalyze the transesterification of cutin precursors in vitro, and can modify tomato fruit cutin structure in semi-in vivo assays. Tomato mutant knockout lines of CUS and CDEF genes generated by CRISPR/Cas9 and cross mutations with cus1 (previously cd1) were found to exhibit different fruit and flower phenotypes related to cutin assembly, including an effect on cutin monomer esterification, composition and content, cutin nanoridge formation in flowers, fruit cuticle permeability and permeance. Characterization of the mutant phenotypes, in combination with the enzyme analysis and bioassays, revealed distinct differences in the contribution of CUS and CDEF enzymes to cutin biosynthesis and remodeling. Our analysis also revealed unexpected spatiotemporal variation in cutin polymerization and structure coordinated by distinct GDSL-hydrolase enzymes over the fruit surface, which further suggests great complexity in cutin deposition and cuticle functions during organ development. HighlightsO_LICutin polymerization in tomato is catalyzed by coordinating the spatiotemporal expression of CUTIN SYNTHASE enzymes in different organs, including during fruit development. C_LIO_LIExtracellular cutin polymerization is not a function limited to the canonical CUTIN SYNTHASE family members but can be also be catalyzed by other GDSL-hydrolase enzymes, as suggested by evidence in vitro. C_LIO_LITomato CDEF enzymes, a clade within the GDSL-hydrolase superfamily, are involved in remodeling cutin structure during fruit development. C_LIO_LIThe biosynthesis and remodeling of cutin over the tomato fruit surface is spatially heterogeneous. C_LI

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↗

bioRxiv2020

Callose deposition is essential for the completion of cytokinesis in the unicellular alga Penium margaritaceum

Cytokinesis in land plants involves the formation of a cell plate that develops into the new cell wall. Callose is a {beta}-1,3 glucan that transiently accumulates at later stages of cell plate development and is thought to stabilize the delicate membrane network of the cell plate as it expands. Cytokinetic callose deposition is currently considered specific to multicellular plant species as it has not been detected in unicellular algae. Here we present callose at the cytokinesis junction of the unicellular charophyte, Penium margaritaceum. Notably, callose deposition at the division plane of P. margaritaceum showed distinct, spatiotemporal patterns that could represent distinct roles of this polymer in cytokinesis and cell wall assembly. Pharmacological inhibition of cytokinetic callose deposition by Endosidin 7 treatment resulted in cytokinesis defects, consistent with the essential role for this polymer in P. margaritaceum cell division. Cell wall deposition and assembly at the isthmus zone was also affected by the absence of callose, demonstrating the dynamic nature of new wall assembly in P. margaritaceum. The identification of candidate callose synthase genes provides molecular evidence for callose biosynthesis in P. margaritaceum. The evolutionary implications of cytokinetic callose in this unicellular Zygnematopycean alga is discussed in the context of the conquest of land by plants. Summary StatementEvolutionarily conserved callose in Penium margaritaceum is essential for the completion of cytokinesis.

cell biology↗

bioRxiv2018

Glycerol phosphate acyltransferase 6 controls filamentous pathogen interactions and cell wall properties of the tomato and Nicotiana benthamiana leaf epidermis

The leaf epidermal wall is covered by a cuticle, composed of cutin and waxes, which protects against dehydration and constitutes a barrier against pathogen attack. Cutin monomers are formed by the transfer of 16- or 18-carbon fatty acids to glycerol by glycerol-3-phosphate acyltransferase (GPAT) enzymes, which facilitates their transport to the plant surface. Here we address the dual functionality of pathogen-inducible Glycerol phosphate acyltransferase 6 (GPAT6) in controlling pathogen entry and dehydration in leaves. Silencing of Nicotiana benthamiana NbGPAT6a increased leaf susceptibility to the oomycetes Phytophthora infestans and P. palmivora, whereas stable overexpression of NbGPAT6a-GFP rendered leaves more resistant to infection. A loss-of-function mutation of the orthologous gene in tomato (Solanum lycopersicum), SlGPAT6, similarly resulted in increased susceptibility of leaves to Phytophthora infection concomitant with altered intracellular infection structure morphology. Conversely, Botrytis cinerea disease symptoms were reduced. Modulation of GPAT6 expression predominantly altered the outer cell wall of leaf epidermal cells. The impaired cell wall-cuticle continuum of tomato gpat6-a mutants resulted in increased water loss and these plants had fewer stomata. Our work highlights a hitherto unknown role for GPAT6-generated cutin monomers in controlling epidermal cell properties that are integral to leaf-microbe interactions and limit dehydration.

plant biology↗