Entyloma eranthidis sp. nov. on Eranthis longistipitata from Uzbekistan

A new smut fungus, Entyloma eranthidis on Eranthis longistipitata from Uzbekistan, revealed by molecular, morphological, and ecological evidence, is described and illustrated. It differs from all other species of Entyloma by host specialization on Eranthis and by having longer (≤35(–38) μm) spores and thicker (≤10(–12) μm) spore walls. ITS rDNA sequence analysis indicates that the new species does not cluster with other species of Entyloma on Ranunculaceae.

Reactive oxygen species are required for spore-wall formation in Physcomitrella patens

A robust spore wall was a key requirement for terrestrialization by early plants. Sporopollenin in spore and pollen grain walls is thought to be polymerized and cross-linked to other macromolecular components, partly through oxidative processes involving H2O2. Therefore, we investigated effects of scavengers of reactive oxygen species (ROS) on the formation of spore walls in the moss Physcomitrella patens (Hedw.) Bruch, Schimp & W. Gümbel. Exposure of sporophytes, containing spores in the process of forming walls, to ascorbate, dimethylthiourea, or 4-hydroxy-TEMPO prevented normal wall development in a dose, chemical, and stage-dependent manner. Mature spores, exposed while developing to a ROS scavenger, burst when mounted in water on a flat slide under a coverslip (a phenomenon we named “augmented osmolysis” because they did not burst in phosphate-buffered saline or in water on a depression slide). Additionally, the walls of exposed spores were more susceptible to alkaline hydrolysis than those of the control spores, and some were characterized by discontinuities in the exine, anomalies in perine spine structure, abnormal intine and aperture, and occasionally, wall shedding. Our data support the involvement of oxidative cross-linking in spore-wall development, including sporopollenin polymerization or deposition, as well as a role for ROS in intine/aperture development.

A comparative study of extraction techniques for maximum recovery of bioactive compounds from Ganoderma lucidum spores

This study aimed at evaluating effective methods for breaking the hard and insoluble spores of Ganoderma lucidum to recover functional biomolecules. Rupture techniques were evaluated such as manual maceration (RM), maceration with spheres of various materials (BR), and microwave exposure plus maceration with steel/chrome spheres (MBR1). Spore rupture was evaluated using UV-Vis spectroscopy, which showed vibrations of 2955, 1642, 1240, 1080 and 1746 cm-1 corresponding to changes in spore walls. The MBR1 extract contained the largest amounts of carbohydrates (19.80 mg.g-1 spores) and polyphenols (2.21 mg.g-1 spores), whereas the BR extract had higher antioxidant activity (57.22%Inb DPPH). The MBR1 and BR extracts contained 62.2 and 73.5% glucose, respectively. Both methods also involved significant extraction of carbohydrates and proteins. The best way to extract biomolecules from spore walls is to perform a microwave heat treatment and break the walls with steel/chrome spheres; this produces large quantities of carbohydrates with antioxidant properties.

Experimental ‘morphogenesis in miniature’ illuminates the evolution and development of pollen wall patterns. A commentary on: ‘Mimicking pollen and spore walls: self-assembly in action’

This article comments on: Nina I. Gabarayeva, Valentina V. Grigorjeva and Alexey L. Shavarda. 2019. Mimicking pollen and spore walls: self-assembly in action. Annals of Botany 123(7): 1205–1218.

Mimicking pollen and spore walls: self-assembly in action

Background and Aims Decades of research have attempted to elucidate the underlying developmental mechanisms that give rise to the enormous diversity of pollen and spore exines. The organization of the exine starts with the establishment of an elaborate glycocalyx within which the subsequent accumulation of sporopollenin occurs. Ontogenetic studies using transmission electron microscopy of over 30 species from many different groups have shown that the sequence of structures observed during development of the exine corresponds to the sequence of self-assembling micellar mesophases (including liquid crystals) observed at increasing concentrations of surfactants. This suggested that self-assembly plays an important part in exine pattern determination. Some patterns resembling separate layers of spore and pollen grain walls have been obtained experimentally, in vitro, by self-assembly. However, to firmly establish this idea, columellate and granulate exines, the most widespread forms, needed to be simulated experimentally. Methods We used our original method, preparing mixtures of substances analogous to those known to occur in the periplasmic space of developing microspores, then leaving the mixtures undisturbed for specific periods of time to allow the process of self-assembly to occur. We developed our method further by using new substances analogous to those present in the periplasmic space and performing the experiments in a thin layer, more closely resembling the dimensions of the periplasmic space. Key Results The artificial microstructures obtained from our in vitro self-assembly experiments closely resembled the main types of exines, including tectate–columellate, granulate, alveolate and structureless, and permitted comparison with both developing and mature microspore walls. Compared with the previous attempts, we managed to simulate columellate and granulate exines, including lamellate endexine. Conclusions Our results show that simple physico-chemical interactions are able to generate patterns resembling those found in exines, supporting the idea that exine development in nature involves an interplay between the genome and self-assembly.

Spore morphology of some Orthotrichaceae Arn. species (Bryophyta) from Turkey

The spores of Orthotrichum lyellii Hook & Taylor, O. speciosum Nees, O. affine Schrad. ex Brid., O. rupestre Schleich. ex Schwagr., O. anomalum Hedw. and O. cupulatum Hoffm. ex Brid. showed the apertural region consists of a leptoma in their spores. Two spore types are characterized by their surface ornamentation, reflecting the species’ taxonomic relationships. The spore shape of all the species is spheroid. The spore size ranged from 7 to 23 μm in the genus Orthotrichum. While the surface ornamentation is verrucate in O. speciosum and O. affine, it is gemmate in O. lyellii, O. rupestre, O. anomalum and O. cupulatum. The spore walls of the family Orthotrichaceae include sclerine (the distinction between exine and perine might be difficult to define) and intine. The examined moss species belong to two habitat types: corticolous and saxicolous. The taxonomic and ecological implications of the genus Orthotrichum were discussed on the basis of its spore morphology.

Rhizopogon roseolus basidiospore germination decreases as the fruiting bodies mature and the spore wall becomes more complex

Rhizopogon roseolus (Corda) Th. Fr. is a basidiomycete truffle that is considered edible. Its gleba changes color from white to beige to brown as it matures. Although ultrastructural changes in the spore wall have been linked to the maturation of the fruiting body, little is known regarding the relationship between spore germination success and the ultrastructure of the spore wall. We examined spore germination on agar plates and analyzed the spore wall ultrastructure using transmission electron microscopy (TEM). Fruiting bodies, collected from a pine forest, were classified into three developmental stages based on gleba color, and the germination success was evaluated at each stage. Variability in the spore germination rate was observed between individual fruiting bodies. The peak germination rate was recorded for the spores from the fruiting bodies in the beige glebal stage, and the rate was lower in the brown glebal stage. When spore wall structures were studied using TEM, the spore wall was found to be multilayered upon maturation of the fruiting body. The spores of the beige glebal stage showed three types of spore walls, namely two-layered, three-layered, and four-layered spore walls. On the other hand, the spores of the brown glebal stage showed predominantly four-layered spore walls. These results indicate that spore germination of R. roseolus decreases as the fruiting body matures and the spore wall becomes more complex.

Jamesdicksonia anadelphiae-trichaetae (Georgefischeriales) and Sporisorium anadelphiae-trichaetae (Ustilaginales), new species on Anadelphia trichaeta (Poaceae) from Guinea

Two new smut fungi on Anadelphia trichaeta, namely Jamesdicksonia anadelphiae-trichaetae and Sporisorium anadelphiae-trichaetae, are described and illustrated from Guinea. Jamesdicksonia anadelphiae-trichaetae differs from J. anadelphiae, infecting Anadelphia pumila in Guinea, by having larger spores (up to 26.5 μm long), thicker spore walls (up to 9.0 μm thick), and erumpent sori. Sporisorium anadelphiae-trichaetae differs from S. monocymbii, infecting Monocymbium ceresiiforme in Sierra Leone, by having spore walls with more prominent ornamentation (spines up to 0.7 μm high) and larger spores. A key to the smut fungi on Anadelphia and related genera is provided.