Klaus Herburger

University of Rostock

The streptophyte green algal class Zygnematophyceae is the immediate sister lineage to land plants. Their special form of sexual reproduction via conjugation might have played a key role during terrestrialization. Thus, studying Zygnematophy-ceae and conjugation is crucial for understanding the conquest of land. Moreover, sexual reproduction featur...

Root hairs are highly elongated tubular extensions of root epidermal cells with a plethora of physiological functions, particularly in establishing the root–rhizosphere interface. Anisotropic expansion of root hairs is generally thought to be exclusively mediated by tip growth—a highly controlled apically localized secretion of cell wall material-e...

High-amylose maize starch (HAMS) can provide dietary fiber to foods. In this study, we investigated the effects of three HAMSs (Gelose 50, Hylon VII, and NAFU50) on the functionality of casein (CA) and/or whey protein (WP) networks in acidified milk gels using normal maize starch (NMS) as a control thickener. When compared with NMS, HAMSs performed...

Octenyl succinate anhydride (OSA) modified high amylose maize starch (HAMS) showed limited emulsion stability due to the OSA groups were located on the surface of starch granules. However, amylose is enriched in the internal region of HAMS and provides the reaction site for OSA groups. In this study, five types of starches with different amylose co...

We investigated the effects of drought stress (DS) on maize varieties with different amylose content (AC). In starches with AC of 33 %, DS increased the contents of amylopectin (AP) chains with a degree of polymerization (DP) > 36 and decreased the AP chains with DP ≤ 36, while the AC was unchanged. DS decreased the crystallinity, the thickness of...

Starch with a high amylose (AM) content (high AM starch, HAS) has attracted increasing research attention due to its industrial application potential, such as functional foods and biodegradable packaging. In the past two decades, HAS structure, functionality, and applications have been the research hotspots. However, a review that comprehensively s...

Background Enzymatic modification of foods is an important tool for enhancing starch functionality due to its safety, high efficiency, and specificity. Enzymatic modification of gelatinized starch systems is well reported in literature. However, to our knowledge, a review describing and comparing the effects of granular vs. gelatinized systems and...

Galactose toxicity is a widespread phenomenon ranging from E.coli to mammals and plants. In plants, the predominant pathway for the conversion of galactose into UDP-galactose and UDP-glucose is catalyzed by the enzymes galactokinase, UDP-sugar pyrophosphorylase and UDP-galactose 4-epimerase. Galactose is a major component of cell wall polymers, gly...

Mougeotia spp. collected from field samples were investigated for their conjugation morphology by light- , fluorescence-, scanning- and transmission electron microscopy. During a scalarifom conjugation, the extragametangial zygospores were initially surrounded by a thin cell wall that developed into a multi-layered zygospore wall. Maturing zygospor...

A method for efficient functional modification of starch granules by thermal ethanol (ETH) pretreatment and subsequent maltogenic α-amylase (MA) and branching enzyme (BE) posttreatments is described. Ethanol pre-treatment significantly increased the swelling power of starch granules thereby increasing the MA and BE susceptibility. ETH pre-treated g...

Extreme environments, such as alpine habitats at high elevation are increasingly exposed to man-made climate change. Zygnemaotophyceae thriving in these regions posess aspecial way of sexual reproduction, termed conjugation, leading to the formation of resistant zygospores. A field sample of Spirogyra with numerous conjugating stages was isolated a...

The extracellular matrix of plants can contain the hydrophobic biopolymers lignin, suberin and/or cutin, which provide mechanical strength and limit water loss and pathogen invasion. Due to their remarkable chemical resistance, these polymers have a high potential in various biotechnological applications and can replace petrol-based resources, for...

Supplemental irrigation (SI) is an important strategy to improve the water-use efficiency (WUE) of crops without compromising the yield. However, such strategy can influence the starch and grain quality. Hence, the effects of SI on winter wheat starch structure and functionality were studied on ridge-furrow (RF) and flat tillage (FT) treated fields...

Due to the semi-crystalline structure of native starch granules, enzymatic modification of these solid, raw, entities by branching enzyme (BE) is limited. Here, we describe a method to efficiently modify starch by BE after maltogenic α-amylases pre-treatment. This pre-treatment produced pores in the starch granule surface, which decreased the granu...

Plant cell wall-derived biomass serves as a renewable source of energy and materials with increasing importance. The cell walls are biomacromolecular assemblies defined by a fine arrangement of different classes of polysaccharides, proteoglycans, and aromatic polymers and are one of the most complex structures in Nature. One of the most challenging...

The plant apoplast contains the four hydrophobic polymer, lignin, suberin, cutin, and cutan, that are crucial for stress resistance, controlling solute diffusion, and strengthening the cell wall. Some of these polymers are widely used in industry and daily life products, such as all wood-containing goods (lignin) and wine cork (suberin). Despite th...

Certain transglucanases can covalently graft cellulose and mixed‐linkage β‐glucan (MLG) as donor substrates onto xyloglucan as acceptor substrate and thus exhibit cellulose:xyloglucan endotransglucosylase (CXE) and MLG:xyloglucan endotransglucosylase (MXE) activities in vivo and in vitro. However, missing information on factors that stimulate or in...

The Equisetum enzyme hetero-trans-β-glucanase (HTG) covalently grafts native plant cellulose (donor-substrate) to xyloglucan (acceptor-substrates), potentially offering a novel 'green' method of cellulose functionalisation. However, the range of cellulosic and non-cellulosic donor substrates that can be utilised by HTG is unknown, limiting our insi...

Current cell-wall models assume no covalent bonding between cellulose and hemicelluloses such as xyloglucan or mixed-linkage β-d-glucan (MLG). However, Equisetum hetero-trans-β-glucanase (HTG) grafts cellulose onto xyloglucan oligosaccharides (XGOs) – and, we now show, xyloglucan polysaccharide – in vitro, thus exhibiting CXE (cellulose:xyloglucan...

Land plants inherited several traits from their green algal ancestors (Zygnematophyceae), including a polysaccharide-rich cell wall, which is a prerequisite for terrestrial survival. A major component of both, land plant and Zygnematophyceaen cell walls is the pectin homogalacturonan (HG) and its high water holding capacity may have helped algae to...

Mixed-linkage glucan (MLG) is a polysaccharide that is highly abundant in grass endosperm cell walls and present at lower amounts in other tissues. Cellulose synthase-like F (CSLF) and cellulose synthase-like H (CSLH) genes synthesize MLG, but it is unknown if other genes participate in the production and restructuring of MLG. Using Brachypodium di...

Many alpine streams inhabit conspicuous epilithic biofilms on pebbles and rocks that are formed by members of the cyanobacterial genus Chamaesiphon (Synechococcales). In the Austrian Alps, some Chamaesiphon species can even overgrow up to 70% of the surface of river rocks, and hence they must play an important but still unstudied ecological role in...

Cell wall-modifying enzymes have been previously investigated in charophyte green algae (CGA) in cultures of uniform age, giving limited insight into their roles. Therefore, we investigated the in situ localisation and specificity of enzymes acting on hemicelluloses in CGA genera of different morphologies and developmental stages. In vivo transglyc...

The phylogenetic placement of Prasiola calophylla, from an anthropogenic habitat previously shown to contain a novel UV-sunscreen compound, was confirmed by analysis of its rbcL gene. This alga has the capacity to tolerate strong water limiting conditions. The photosynthetic performance and ultrastructural changes under desiccation and osmotic stre...

The genus Klebsormidium (Klebsormidiales, Streptophyta) has a worldwide distribution in terrestrial habitats. In the present study, we focused on two strains of Klebsormidium flaccidum, the type species of the genus. The isolates used in this study were isolated from soil and freshwater habitats. Photosynthetic activity was evaluated under differen...

Plant including green algal cells are surrounded by a cell wall, which is a diverse composite of complex polysaccharides and crucial for their function and survival. Here we describe two simple protocols to visualize callose (β-1→3-glucan) and cellulose (β-1→4-glucan) and related polysaccharides in the cell walls of streptophyte green algae by usin...

The green-algal class Klebsormidiophyceae (Streptophyta), which occurs worldwide, comprises the genera Klebsormidium, Interfilum, Entransia and Hormidiella. Ecophysiological research has so far focused on the first two genera because they are abundant in biological soil crust communities. The present study investigated the photosynthetic performanc...

Streptophyte green algae, ancestors of Embryophytes, occur frequently in terrestrial habitats being exposed to high light intensities, water scarcity and potentially toxic metal cations under acidic conditions. The filamentous Zygogonium ericetorum synthesises a purple vacuolar ferrous pigment, which is lost after aplanospore formation. However, it...

Microtubules (MTs) are required throughout plant development for a wide variety of processes, and different strategies have evolved to visualize and analyze them. This chapter provides specific methods that can be used to analyze microtubule organization and dynamic properties in plant systems and summarizes the advantages and limitations for each...

Reproductive characteristics are important for defining taxonomic 32 groups of filamentous Zygnematophyceae, but they have not been fully observed in the genus Zygogonium. Specimens of Z. ericetorum previously studied and used to clarify the generic concept of the genus lacked fertile material, which was obtained recently. The current study illustr...

Freshwater green algae started to colonise terrestrial habitats about 460 million years ago, giving rise to the evolution of land plants. Today, several streptophyte green algae occur in aero-terrestrial habitats with unpredictable fluctuations in water availability, severing as ideal models for investigating desiccation tolerance. We tested the hy...

Green algae of the genus Klebsormidium (Klebsormidiales, Streptophyta) are typical members of biological soil crusts (BSCs) worldwide. The phylogeny and ecophysiology of Klebsormidium has been intensively studied in recent years, and a new lineage called superclade G, which was isolated from BSCs in arid southern Africa and comprising undescribed s...

Green algae of the genus Klebsormidium (Klebsormidiales, Streptophyta) are typical members of biologicalsoil crusts (BSCs) worldwide. The phylogeny and ecophysiology of Klebsormidium has been intensivelystudied in recent years, and a new lineage called superclade G, which was isolated from BSCs in aridsouthern Africa and comprising undescribed spec...

Main conclusion Desiccation leads to structural changes of the inner pectic cell wall layers in Ulva compressa . This contributes to protection against mechanical damage due to desiccation–rehydration cycles. Ulva compressa, characterized by rbcL phylogeny, is a common species in the Mediterranean Sea. Ulva as an intertidal species tolerates repe...

Two newly isolated strains of green algae from alpine regions were compared physiologically at different culture ages (1, 6, 9 and 15 months). The strains of Zygnema sp. were from different altitudes ('Saalach' (S), 440 m above sea level (a.s.l.), SAG 2419 and 'Elmau-Alm' (E-A), 1,500 m a.s.l., SAG 2418). Phylogenetic analysis of rbcL sequences gro...

Zygogonium ericetorum, the type species of the genus, was studied from a natural population collected in Mt. Schönwieskopf, Tyrol, Austria. Generic concepts of Zygogonium and Zygnema were tested with atpB, psbC, and rbcL gene sequence analysis, which showed a sister relationship between Zygo. ericetorum and Mesotaenium, in an early branching clade...

Unicellular green algae of the genus Interfilum (Klebsormidiales, Streptophyta) are typical components of biological soil crusts. Four different aeroterrestrial Interfilum strains that have previously been molecular-taxonomically characterized and isolated from temperate soils in Belgium, Czech Republic, New Zealand and Ukraine were investigated. P...

The osmotic potential and effects of plasmolysis on photosynthetic oxygen evolution and chlorophyll fluorescence were studied in two Arctic Zygnema sp. (strain B, strain G) and two Antarctic Zygnema sp. (strain E, strain D). Antarctic strain D was newly characterized by rbcL sequence analysis in the present study. The two Antarctic strains, D and E...