Biology subjects

Marcus, S. E.

Publications and source records attributed to Marcus, S. E..

3 recordsLinked to original sources

bioRxiv2024

Structurally diverse calloses/β-1,3-glucans in plant cell wall microdomains

Cell walls underpin the mechanics of cell growth, intercellular signalling, and defence against pathogenic organisms. {beta}-(1,3)-glucans (also known as callose) are polysaccharides found in plants, fungi, and some bacterial species. In developing plant organs, callose accumulates around intercellular channels (plasmodesmata) controlling cell-to-cell communication. We developed monoclonal antibodies for the detection of {beta}-(1,3)-glucans and using these identified distinct populations of callose differing in size and secondary structure. Callose sub-populations were in proximal but not overlapping cell wall microdomains implying distinct spatial and functional microenvironments. We also unveiled callose interaction with xyloglucan; another plant glycan regulating cell wall functions. This work challenges previous views demonstrating structural heterogeneity in plant callose and supporting interactions between glycans with roles in the regulation of cell wall properties and functions.

plant biology↗

bioRxiv2021

A soil-binding polysaccharide complex released from root hairs functions in rhizosheath formation

To elucidate factors involved in rhizosheath formation, wild type (WT) barley (Hordeum vulgare L. cv. Pallas) and a root hairless mutant, bald root barley (brb), were investigated with a combination of physiological, biochemical and immunochemical assays. When grown in soil, WT barley roots bound [~]5-fold more soil than brb per unit root length. High molecular weight (HMW) polysaccharide exudates of brb roots had less soil-binding capacity than those of WT root exudates. Carbohydrate and glycan monoclonal antibody analyses of HMW polysaccharide exudates indicated differing glycan profiles. Relative to WT plants, root exudates of brb had reduced signals for arabinogalactan-protein (AGP), extensin and heteroxylan epitopes than brb. In contrast, the brb root exudate contained [~]25-fold more detectable xyloglucan epitope relative to WT. Epitope detection chromatography indicated that the increased detection of xyloglucan in brb exudates was due to enhanced abundance of a neutral polymer. Exudate preparations from brb had decreased amounts of an acidic form of xyloglucan associated with root-hair located glycoprotein and heteroxylan epitopes and with soil-binding properties. Therefore, in addition to physically structuring soil particles, root hairs facilitate rhizosheath formation by releasing a soil-binding polysaccharide complex. One sentence summaryThe root exudate of a root hairless mutant of barley, relative to wild type, has an altered pattern of polysaccharide epitopes and lesser amounts of an acidic soil-binding polysaccharide complex.

plant biology↗

bioRxiv2017

LM6-M: a high avidity rat monoclonal antibody to pectic α-1,5-L-arabinan

1,5-arabinan is an abundant structural feature of side chains of pectic rhamnogalacturonan-I which is a matrix constituent of plant cell walls. The study of arabinan in cells and tissues is driven by putative roles for this polysaccharide in the generation of cell wall and organ mechanical properties. The biological function(s) of arabinan is still uncertain and high quality molecular tools are required to detect its occurrence and monitor its dynamics. Here we report a new rat monoclonal antibody, LM6-M, similar in specificity to the published rat monoclonal antibody LM6 (Willats et al. (1998) Carbohydrate Research 308: 149-152). LM6-M is of the IgM immunoglobulin class and has a higher avidity for -1-5-L-arabinan than LM6. LM6-M displays high sensitivity in its detection of arabinan in in-vitro assays such as ELISA and epitope detection chromatography and in in-situ analyses.\n\nAbbreviations

plant biology↗