Simple Spore Research Articles

Simplifying Barley Leaf Rust Research: An Easy and Reproducible Infection Protocol for Puccinia hordei on a Small Laboratory Scale.

Barley (Hordeum vulgare) is one of the most important agricultural crops in the world, but pathogen infections regularly limit its annual yield. A major threat is the infection with the biotrophic leaf rust fungus, Puccinia hordei. Rust fungi have a complex life cycle, and existing resistances can be easily overcome. To address this problem, it is crucial to develop barley varieties with improved and durable resistance mechanisms. An essential step towards this goal is a simple and reproducible infection protocol to evaluate potential resistance phenotypes in the lab. However, available protocols sometimes lack detailed procedure or equipment information, use spore application methods that are not suitable for uniform spore dispersion, or require special mineral oils or engineered fluids. In addition, they are often optimized for pathogen-dedicated greenhouses or phytochambers, which may not be available to every research institute. Here, we describe an easy and user-friendly procedure to infect barley with Puccinia hordei on a small laboratory scale. This procedure utilizes inexpensive and simple tools to evenly split and apply spores to barley leaves. The treated plants are incubated in affordable and small phytocabinets. Our protocol enables a quick and reproducible infection of barley with leaf rust, a method that can easily be transferred to other rust fungi, including stripe rust, or to other plant species. Key features Step-by-step infection protocol established for barley cv. Golden Promise, the gold standard genotype for genetic transformation Plant age-independent protocol Precise spore application by using inexpensive pipe cleaners for uniform symptom formation and increased reproducibility No specialized equipment needed Includes simple spore harvesting method Protocol is applicable to other biotrophic pathogens (stripe rust or powdery mildew) and other plants (e.g., wheat) Protocol is also applicable for a detached leaf assay Graphical overview.

A terrestrial Devonian-Carboniferous boundary section in East Greenland

Terrestrial Devonian-Carboniferous boundary sections are present in the East Greenland Devonian Basin. The boundary section on Stensiö Bjerg developed in deep, distal lake sediments with a pair of lakes representing the boundary. A diverse spore assemblage developed as the lake flooded the basin. Previously abundant spores, notably Retispora lepidophyta, Diducites spp., Rugospora radiata and all forms with bifurcate tips (Ancyrospora and Hystricosporites), then became extinct through just over a metre of section. The spore assemblage is then lost into AOM rich very high TOC% lake sediments. There is a negative δ13CTOC excursion in the Stensiö Bjerg section interpreted to represent the upper part of the positive excursion known from marine sections. The upper lake contains the simple VI spore assemblage of the earliest Carboniferous age. The correlative section on Rebild Bakker was developed in shallow proximal facies without AOM and shows that a Devonian-Carboniferous LN* to VI spore zone boundary can be picked in the lower lake based on the last occurrence of Retispora lepidophyta in an assemblage otherwise dominated by simple spores and Grandispora cornuta. Spores in this VI spore assemblage, particularly Grandispora cornuta, show sculpture malformation that is entirely characteristic of UV-B radiation damage to their DNA prior to deposition of its protective wall layer. This palynological record showing the rapid extinction of major elements within the Late Devonian microflora can be reconciled with accounts claiming there was no mass extinction of plants and spores across the boundary. The palaeobiology of the major spore groups that became extinct is reviewed.

Palynological calibration of Devonian events at near-polar palaeolatitudes in the Falkland Islands, South Atlantic

Abstract In the Devonian, the Falkland Islands were part of the high-latitude Cape Basin. West Falkland palynological assemblages are at a low thermal maturity level but also very low in diversity and dominated by simple spores with rare chitinozoans and acritarchs. The South Harbour Member contains rare verrucate and sculptured trilete spores, and is early Lochkovian. The Fish Creek Member palynofloras are late Lochkovian. The best correlative datum is the transgressive Fox Bay Formation where the palynological assemblage includes Ramochitina magnifica and is equivalent to the Sequence B transgression in Brazil (dated as late Pragian–earliest Emsian). The early Eifelian upper Fox Bay Formation spore assemblage is comparable to the Sequence C transgression in Brazil and the ?Choteč Event. The facies and position of the base Port Philomel Formation prasinophyte-rich black shale suggests the late Eifelian transgression (Kačák Event). Above this level is the inception of Geminospora lemurata (base Givetian). The upper Port Stanley Formation contains a late (but not latest) Famennian assemblage. Comparisons with both South Africa and South America indicate a number of correlative transgressive and regressive events that match to Euramerica. These correlations are at a continental scale and confirm eustatic control of these Devonian events.

Three new arbuscular mycorrhizal Diversispora species in Glomeromycota

Morphological observations of spores and mycorrhizal structures of three arbuscular mycorrhizal fungi (Glomeromycota) prompted, and subsequent phylogenetic analyses of SSU–ITS–LSU nrDNA sequences confirmed, that they are undescribed species of the genus Diversispora. Morphologically, the first species, here named D. varaderana, is most distinguished by its relatively small (≤90 μm diam when globose) and yellow-coloured spores with a simple spore wall consisting of two layers, of which layer 1, forming the spore surface, is short-lived and usually completely sloughed in most spores. The distinctive features of the second species, D. peridiata, are the occasional formation of spores in clusters and peridium-like hyphae covering the clusters and single spores, and especially the permanent and relatively thick spore wall layer 1, which is the only coloured component of the two-layered spore wall of the yellow-coloured and relatively small spores (≤100 μm diam). The third species, D. slowinskiensis, is most characterized by its spore wall layer 1 that is the only coloured component of the three-layered spore wall and frequently is covered with blister-like swellings. All the three species were grown in single-species cultures established from spores extracted from trap cultures inoculated with rhizosphere soils of plants growing in maritime sand dunes: D. varaderana from those located near Varadero on the Hicacos Peninsula, Cuba, and the two others from those of the Slowinski National Park, northern Poland.

Biogeographical variability and re-description of an imperfectly known species Hamatocanthoscypha rotundispora (Helotiales, Hyaloscyphaceae)

Study on fresh collections and type material of Hamatocanthoscypha rotundispora showed that the original description is incomplete and that the variation range in the essential characters is too narrowly defined. In this paper we therefore provide a detailed description, including ascospore morphometry using length, width, length/width ratio and volume. Non-parametric statistics showed significant deviation of normal distribution and high variability of all morphometrical variables, suggesting that use of living material for ascospore morphometrical analysis is more reliable than that of a traditional approach. Geometric criteria for defining the simple spore shape regarding the length/width ratio, polarity and symmetry in straight symmetric spores are proposed. Refractive cytoplasmic globules are described as a new type of inclusions in living cells. Species ecology and biogeography is also discussed.

Genetic diversity of the lichen-forming alga,Diplosphaera chodatii, in North America and Europe

AbstractDermatocarpon luridumis a subaquatic lichen which is distributed within temperate climatic zones around the world. It colonizes rock substrata along the shoreline of lakes and rivers of watersheds that regularly experience water level fluctuations. The mycobiont produces perithecia with small, simple spores that are thought to be wind dispersed. The photobiont,Diplosphaera chodatii, occurs both free-living and lichenized but little is known about its distribution and dispersal. The goal of this study was to compare the population structure of the photobiont from lakes and rivers in central North America with those of Europe. Specimens were collected in Manitoba, Canada and Austria. Population structure of the algal symbiont was assessed using the internal transcribed spacer (ITS) of ribosomal DNA (rDNA) and actin gene sequences. Results showed that genetic diversity and gene flow was high within local populations, but gene flow was low between continental populations. Low levels of gene flow between the most distant populations support the isolation-by-distance theory. The photobiont on both continents is also reported to be the photobiont for other lichen species contributing to photobiont availability forD. luridum.

Umbilicaria semitensis (lichenized fungi: Umbilicariaceae) resurrected

Abstract Umbilicaria semitensis was described by Tuckerman in 1872 based on a specimen from Yosemite National Park. Despite the species having muriform spores, in contrast to simple spores in U. angulata, U. semitensis has long been treated as a synonym of U. angulata, owing to the superficial similarities of the thallus. Analysis of the ITS and LSU regions of nrDNA supports the hypothesis that the species are distinct. In addition to the spore and DNA differences, the two species are largely allopatric, and only know to co-occur in one site in Oregon. Umbilicaria semitensis ranges from southern California to southern Oregon, while U. angulata ranges from California to arctic Alaska.

The influence of plant injury on development of Mycosphaerella pinodes in field pea

Plants of field pea, Pisum sativum ‘AC Tamor’, were mechanically injured by sandblasting and inoculated with Mycosphaerella pinodes immediately after this pretreatment and 1, 2, 4, and 8 days later under controlled conditions. A negative linear relationship was observed between disease severity, measured as the area under the disease progress curve over a period of 17 days, and the time elapsed between injury and inoculation. Control plants, without injury, were inoculated parallel to the injured plants and did not show this response. Inoculation up to 24 h after injury resulted in significantly higher disease severity than inoculation after that period or inoculation of control plants, suggesting that injury facilitates infection of the pea plant by M. pinodes prior to the formation of callus. In field experiments, differences between injury and control treatments of nine field pea genotypes (cultivars and germplasm accessions) were apparent only a few weeks after inoculation. Disease severity in the second half of the cropping season that was characterized by above-average precipitation was similar in all treatments. This indicates that plant injury plays a minor role in the establishment and development of M. pinodes when conditions are conducive to an epidemic outbreak of the disease. Spore production was monitored with simple spore traps in plots with and without injury treatment and did not show any difference in spore numbers.

Ptychographa, a Lichen Genus New to North America

The genus Ptychographa is reported in North America from Oregon and Washington. Ptychographa xylographoides Nyl. is a lirellate crustose lichen that occurs exclusively on decorticate wood. The species is characterized by a dark brown to black exciple, simple spores, and a hymenium that is partitioned lengthwise. It grows at all levels in the canopy in old-growth conifer forests in the Cascade Range and has also been found on coarse woody debris in younger forests. Ptychographa xylographoides Nyl. is a lirellate crustose lichen that occurs exclusively on wood. This species has been found in coniferous forests in western Oregon and Washington. Originally it was found from the gondola suspended by the Wind River Canopy Crane, a large construction crane installed in an old-growth forest at T. T. Munger Research Natural Area. An ongoing study with Roger Rosentreter, Jeanne Ponzetti, and Dave Shaw disclosed that this species is fairly frequent on dead in the canopy. The species had previously been reported only from the British Isles. The local material matches the description in the British flora (Purvis et al. 1992, p. 514) in most details. The substrate in Great Britain is apparently more restrictive than in the Pacific Northwest. Purvis et al. (1992) reported it on wood of ? horizontal surfaces of fallen trees, while we found it on both vertical and horizontal at all levels in the canopy. Superficially Ptychographa appears similar to some local Opegrapha species, forming jet black, elongate apothecia. Anatomically it is quite distinct however. Ptychographa has simple colorless spores in contrast to the multiseptate spores of Opegrapha. Furthermore, the hymenium of Ptychographa is usually divided by a longitudinal ridge of dark, sterile tissue (Figs. 1, 2). These lengthwise divisions of the hymenium are most easily seen in transverse section (Fig. 2), but I have found it to be a useful hand-lens character for field identification. Look for an extra fold or ridge between the two marginal ridges of exciple (Fig. 1) Xylographa, while sharing the simple spores of Ptychographa, is easily separated by its pale excipie, in contrast to the dark, carbonaceous exciple of Ptychographa. Although the exciple of Xylographa can be dark when viewed with a handlens, a thin section under the compound microscope will always reveal a pale inner exciple, even when the surface is dark. Furthermore, Xylographa lacks the distinctive bands of sterile tissue found in Ptychographa. The thallus of Ptychographa is inconspicuous, usually consisting of minute brownish granules (containing the green photobiont) that are widely scat ered on a whitish background. The granules are

Differential tolerance to Cd and Zn of arbuscular mycorrhizal (AM) fungal spores isolated from heavy metal-polluted and unpolluted soils

Spores of arbuscular mycorrhizal fungi were isolated from two soils of field trials at INRA-Bordeaux (France) polluted by long-term application of a zinc-polluted sewage sludge (S2 soil) or treated with cadmium nitrate (Cd40 soil) and from corresponding unpolluted soils (F and Cd0 soils). These AM fungi were tested for their tolerance to Cd and Zn added as salt solutions with increasing concentrations (0 to 10 mg L−1) in a simple spore germination device.

Horizontal and vertical distribution of airborne conidia of Botrytis cinerea in a gerbera crop grown under glass

The horizontal and vertical distribution of airborne conidia ofBotrytis cinerea in a gerbera crop in two glasshouses (100 m2 and 350 m2) was studied during 18 months in 1988 and 1989. Conidia ofB. cinerea were caught in simple spore traps consisting of agar in Petri dishes placed in a regular pattern at three different heights in the glasshouse and counted as colonies, after incubation. Lesions due to conidial infection were counted on gerbera petals. The horizontal and vertical distribution of conidia ofB. cinerea in a gerbera crop grown under glass was fairly uniform in both distinct glass-houses. Conidia ofB. cinerea trapped in a glasshouse can originate from sources inside and outside the glasshouse. No significant interaction was found between location and time for the colony counts and for the log transformed (ln(N+1)) lesion counts. The results of this study suggest that spore trapping at one height and at a limited number of locations and dates is sufficient for efficient monitoring ofB. cinerea in a glasshouse.

The Study of Algae

What exactly are those curious plants known as algae? The answer to this question is actually difficult, but a few distinguishing characteristics of algae help in identifying and understanding them. First of all, nearly all algae are colored by the photosynthetic pigments which they contain. Some are blue-green in color, others grass-green, and still others golden, red, or brown. The specific pigments contained within the algal cells represent one important means of classifying algae. Second, algae reproduce by cell division, by fragmentation, or by the production of simple spores, but never by seeds. Third, algae are simple in construction when compared to the more complex land plants. They do not produce organs such as roots, stems, or leaves, even though some of the sea weeds are rather complex. And fourth, most algae inhabit the aquatic rather than terrestrial environment or at least are dependent upon moisture for reproduction.

Some Lower Devonian microfloras from Southern Britain

A new spore assemblage of Siegenian age from Llanover, south Wales is described, and compared with an assemblage of Gedinnian age recently described by Chaloner and Streel (1966) from Newport, south Wales. These are compared with other new assemblages from the Faringdon borehole, the Brightling No. 1 borehole and the Canvey Island borehole, all in the southern half of England and known from other fossils to be probably of Lower Devonian age. All five assemblages are dominated by relatively simple spore types. The Siegenian assemblage shows only a small increase in morphographical variety over the Gedinnian assemblage, but a considerable increase in the mean maximum size of the spores studied. The borehole assemblages show approximately the same size range as the Siegenian assemblage, but differ in a progressive increase in the variety of morphography represented. All are concluded to be younger, and are placed in an order according to age. Spores with bifurcate spines appear in the Canvey Island material. The youngest assemblage, from Brightling, shows a marked increase in variety over the others, and includes saccate and zonate forms as well as those with bifurcate spines. This is regarded as consistent with an Emsian age.

Problems in the Systematics of the “Sporozoa”*

The taxonomy of the so‐called Sporozoa is reviewed, and it is concluded that the group is polyphyletic and should be split into the following independent taxa: (1) The subphylum EUSPORA subph. nov., members of which have simple spores without polar filaments; this subphylum contains the classes TELOSPORASIDA Schaudinn, 1900 and HAPLO‐SPORASIDA Caullery and Mesnil, 1899; (2) the subphylum CNIDOSPORA Doflein, 1901, members of which have spores containing 1 or more polar filaments; (3) the class PIRO PLASMASIDA Wenyon, 1926, members of which have no spores, are parasitic in vertebrate erythrocytes and are heter‐oxenous; and (4) the class TOXOPLASMASIDA Biocca, 1957 emend., members of which have no spores, have cysts or pseudocysts, and are monoxenous parasites of vertebrates; the latter two groups are not assigned to subphyla but are considered appendages to the Protozoa. A classification to suborders is given of the Euspora.