Chromosomal distribution of H3K4me2, H3K9me2 and 5-methylcytosine: variations associated with polyploidy and hybridization in <Emphasis Type="Italic">Brachiaria</Emphasis> (Poaceae)

Key message

Assessment of chromosomal distribution of modified histones and 5-methylcytosine shown that there are diversification of chromosomal types among species of Brachiaria and its interspecific hybrids.

Abstract

Histone post-translational modifications and DNA methylation are epigenetic processes that are involved in structural and functional organization of the genome. This study compared the chromosomal distribution of modified histones and 5-methylcytosine (5-mCyt) in species and interspecific hybrids of Brachiaria with different ploidy levels and reproduction modes. The relation between H3K9me2 and 5-mCyt was observed in the nucleolus organizer region, centromeric central domain and pericentromeric region. H3K4me2 was detected in euchromatic domains, mainly in the terminal chromosomal regions. Comparison of chromosomal distribution among species and hybrids showed greater variation of chromosomal types for the H3K9me2 in B. decumbens (tetraploid and apomictic species) and the 963 hybrid, while, for the H3K4me2, the variation was higher in B. brizantha and B. decumbens (tetraploid and apomictic species) and 963 hybrid. The chromosome distribution of 5-mCyt was similar between B. brizantha and B. decumbens, which differ from the distribution observed in B. ruziziensis (diploid and sexual species). Significant alterations in DNA methylation were observed in the artificially tetraploidized B. ruziziensis and in the interspecific hybrids, possibly as result of hybridization and polyploidization processes. The monitoring of histone modifications and DNA methylation allowed categorizing nuclear and chromosomal distribution of these epigenetic marks, thus contributing to the knowledge of composition and structure of the genome/epigenome of Brachiaria species and hybrids. These data can be useful for speciation and genome evolution studies in genus Brachiaria, and represent important markers to explore relationships between genomes.

     

Aeropalynological study of two selected locations in North-Central Nigeria

Pollen and spores have been found as major biological sources of morbidity among individuals sensitive to respiratory disorders. The aim of the present study was to analyse the deposition rate of atmospheric pollen and fern spores at selected sites in Benue and Plateau states of the North-Central Nigeria between July 2015 and June 2016. This was accomplished by: (1) determining the pollen and fern spore content of each monitoring station; (2) establishing the relationship between total pollen count and meteorological parameters; and (3) comparing the recovered airborne pollen spectra with identified plants in the surrounding vegetation types of the sampling sites. The collection of atmospheric pollen was done using a modified Tauber sampler and plants in the surrounding environment of the sampling sites were enumerated. The residual solution was collected monthly and acetolysed, after which slide preparation and microscopy of the treated residue were done. Meteorological data were obtained from the Nigerian Meteorological Agency, Lagos. The results obtained reveal seasonal distribution patterns of various airborne pollen grains in the study locations. The most abundant pollen types recovered in Plateau State were produced by Syzygium guineense, Tridax procumbens, Alchornea sp., Terminalia sp., Poaceae and Amaranthaceae. Pollen types of Casuarina equisetifolia, Syzygium guineense, Tridax procumbens, Poaceae and Cyperaceae were preponderant in Benue State. Pteris sp., Nephrolepis sp. and a trilete fern spore were also represented in this study. The recovered airborne pollen spectra correspond favourably with some identified plants in the study locations. There was no significant correlation between monthly total pollen count and mean monthly values of meteorological parameters in Benue State. Air temperature and wind speed correlated significantly with monthly total pollen count in Plateau State. It is suggested that the allergenic effect of these abundant pollen types on humans should be further examined.     

Hybridization rate and genotypic diversity of apomictic hybrids between native (<Emphasis Type="Italic">Taraxacum japonicum</Emphasis>) and introduced (<Emphasis Type="Italic">T. officinale</Emphasis>) dandelions in western Japan

Hybridization between the introduced and native plants may enhance invasiveness, especially in asexually reproducing species. Hybrid apomictic dandelions between native (Taraxacum platycarpum and T. japonicum) and exotic (T. officinale) species are distributed widely throughout Japan. To estimate the origin(s) and dispersal of the hybrids, we investigated the hybridization rate and genotypic diversity in mixed populations of T. japonicum, T. officinale and their hybrids at two green parks in western Japan. Among the plants identified as exotics from flower morphology, 86–96% were hybrids by genetic analysis. Genetic data with simple sequence repeat markers revealed a high clonal diversity of the hybrid both within and between populations, indicating multiple origins. A hybrid seed was found from among the 1891 seeds collected from T. japonicum in the parks, indicating ongoing hybridization in the field. T. officinale and hybrids were genetically differentiated between the two parks independent of the ploidy level; the allele frequency of T. officinale and tri- and tetraploid hybrids were similar within each park but different between the two parks. This suggests that the origins of hybrids were similar within the park but different between the parks. Overall, our results suggest that hybridization, including backcross, is an ongoing process, and that genetically diverse hybrids with various origins have been spreading in western Japan, probably because hybridization enhanced invasiveness at native habitat.     

Determination of airborne fungal spores of Gaziantep (SE Turkey)

The aim of this study was to present the first airborne fungal spore research results of SE of Turkey. The presence and abundance of fungal spores were investigated with a Hirst-type volumetric spore trap (Lanzoni, VPSS 2000) for 2 years between the periods January 2010 and December 2011. A total of 211,521 spores and 47 fungal taxa belonging to Anamorphic Fungi, Phyla Ascomycota and Basidiomycota were recorded. Aspergillus/Penicillium spores type, unidentified spores, spores of Myxomycota and hyphal fragments were also recorded as groups. The relationship between fungal spore counts and several meteorological parameters was examined. Cladosporium was determined as the predominant genus (56.48 %); hyphal fragments (14.94 %), Ustilago (13.96 %) and Alternaria (5.79 %) were revealed as the common fungal aerosols of Gaziantep atmosphere. With this study, the first aeromycological survey of SE of Turkey has been conducted and new information on the field of aerobiology in Turkey has been introduced.     

The influence of meteorological parameters on <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> fungal spore concentrations in Beja (Southern Portugal): preliminary results

Introduction Fungal spores constitute an important fraction of bioaerosols in the atmosphere. Objectives To analyse the content of Alternaria and Cladosporium spores in the atmosphere of Beja and the effect of meteorological conditions on their concentrations. Methodology The daily and hourly data of Alternaria and Cladosporium fungal spores concentration in the atmosphere of Beja were monitored from April 12, 2012 to July 30, 2014, based on the Portuguese Aerobiology Network methodology. The influence of meteorological conditions on the studied types of fungal spore concentrations was assessed through Spearman’s correlation analysis. Results During the study period, 20,741 Alternaria spores and 320,862 Cladosporium spores were counted. In 2013, there were 5,822 Alternaria spores and 123,864 Cladosporium spores. The absolute maximum concentrations of Alternaria and Cladosporium spores were recorded on November 8, 2013, with 211 and 1301 spores/m³, respectively. Temperature, insolation and wind direction parameters showed a positive correlation with Alternaria and Cladosporium spore levels, while relative humidity and precipitation presented a negative correlation, which is statistically significant. Wind speed only showed a statistically significant positive correlation in terms of Alternaria spore levels. Conclusion Alternaria and Cladosporium spores are present in the atmospheric air of Beja throughout the year, with the highest concentration period occurring during spring and autumn. There was a clear effect of meteorological parameters on airborne concentrations of these fungal spores.     

First volumetric record of fungal spores in the atmosphere of Montevideo City,Uruguay: a 2-year survey

In Uruguay, aeromycological studies are restricted to a gravimetric analysis performed from December 1942 to March 1944 in Montevideo where spores of Pucciniaceae, Alternaria and Helminthosporium were the only specimens identified. Daily monitoring of airborne fungal spores was carried out for the first time in Montevideo, from April 2012 to March 2014, using a Rotorod sampler in order to evaluate the seasonal variation and influence of meteorological parameters. A total of 548,309.68 spores/m³ were recorded which belong to anamorphs of Higher Fungi (69.18 %), Phyla Ascomycota (12.62 %), Basidiomycota (8.01 %), Oomycota (0.37 %) and Myxomycota (0.06 %). Airborne spores occurred in Montevideo throughout the whole year. However, a seasonal pattern was revealed, with the highest concentrations recorded in autumn and summer. The most abundant spore types were Cladosporium (53.22 %), Alternaria (6.62 %), Didymella Group (5.86 %), Leptosphaeria Group (4.37 %) and Coprinus (4.3 %). Temperature appeared to be the most influential meteorological factor correlating significantly and positively with total spore, Cladosporium, Alternaria and Didymella Group abundance. Relative humidity influenced positively total spore, Cladosporium and Didymella Group concentrations while a weak negative association was obtained for Alternaria. Wind speed correlated negatively with total spore, Cladosporium, Alternaria and Didymella Group. Precipitation showed a negative influence on Alternaria, while positive correlations were observed for Didymella Group. For the first time, fungal spores considered allergenic were recorded in Montevideo atmosphere and the risk of exposure would have been high from December to June. However, long-term sampling is needed to define seasonal prevalence patterns and the influence of meteorological conditions on spore abundance.     

First fungal spore calendar of the middle-west of the Iberian Peninsula

The aim of this paper was to make a first approximation of the fungal spore airborne content in Valladolid along the year, constructing the first spore calendar for the middle-west of Spain. So that, we monitored the city during 2005 and 2006, being Cladosporium the most abundant type, present all over the year (together with Pleospora). The greatest atmospheric spore diversity was observed in April in contrast with February. The intra-diurnal pattern for Alternaria, Cladosporium and Dreschlera was very similar with an hourly concentration percentage decreasing along two periods, whereas Coprinus, Ganoderma and Periconia showed a clearly nocturnal pattern. The meteorological parameter that most influenced airborne spore concentrations was temperature, significantly and positively in the case of dry-air spores but negatively for wet-air spores.     

Atmospheric concentrations of selected allergenic fungal spores in relation to some meteorological factors,in Timişoara (Romania)

Present investigation was undertaken to study the dynamics of relationships between atmospheric fungal spores and meteorological factors in western Romania. The airborne spore sampling was carried out by employing volumetric sampling. A total of nine meteorological parameters were selected for this investigation. During 2008–2010, it was found the same pattern of behaviour in the atmosphere for selected spore types (Alternaria, Cladosporium, Pithomyces, Epicoccum and Torula). The spores occurred in the air throughout the whole year, but maximum concentrations were reached in summer. Cladosporium and Alternaria peak levels were observed in June. Epicoccum peak value was found in September. The relationships between airborne spore concentrations and environmental factors were assessed using the analysis of Spearman’s rank correlations and multiple linear regressions. Spearman’s rank correlation analysis revealed that maximum, minimum and mean temperature, and number of sunshine hours were strongly (p < 0.01) and directly proportional to the concentration of all analysed fungal spores. Negative and significant correlations were with daily mean relative humidity. The variance explained percentage by regression analyses varied between 30.6 and 39.6 % for Alternaria and Cladosporium airborne spores. Statistical methods used in this study are complementary and confirmed stable dependence of Alternaria and Cladosporium spore concentrations on meteorological factors. The climate change parameters either increased temperatures, changed precipitation regimes or a combination of both affected allergenic fungal spore concentrations in western Romania. This study demonstrates the need for investigations throughout the year, from month to month, regarding the correct interpretation of airborne spore relationships with meteorological parameters.     

Comparisons of fungal spore distributions using air sampling at Worcester,England (2006–2010)

This study determined annual and monthly fluctuations in concentration of 20 fungal genera. The selection of taxa was made based upon their high frequency in the air as well as their well-known allergenic properties. Air samples were collected using a spore trap of Hirst design at an urban site where the trap continuously worked throughout a 5-year survey. Weather data were acquired from a meteorological station co-located with the air sampler. Influence of several meteorological parameters was then examined to reveal species–environment interactions and the potential location of fungal spore sources within the urban area. The maximum monthly sum of mean daily spore concentration varied between genera, and the earliest peaks were recorded for Pleospora sp. in April and Ustilago sp. in June. However, the majority of investigated spore types occurred in the greatest concentrations between August and September. Out of the 20 studied taxa, the most dominant genus was Cladosporium sp., which exceeded an allergenic threshold of 3000 s m^?3 40 times during very rainy years and twice as much during dry years. A Spearman’s rank test showed that statistically significant (p ≤ 0.05) relationships between spore concentration and weather parameters were mainly r _s  ≤ 0.50. Potential sources of spores at Worcester were likely to be localised outside the city area.     

A 10-year study of <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> in two Polish cities (Szczecin and Cracow) and relationship with the meteorological parameters

Alternaria and Cladosporium spores belong to the most frequent and allergenic particles in bioaerosol in the temperate climate. The investigation of Alternaria and Cladosporium spore concentrations was performed in two cities in Poland, Szczecin and Cracow, in 2004–2013. The meteorological parameters taken to assess their impact on fungal spores were average, maximum and minimum temperature, relative humidity and average wind velocity. In order to reveal whether changes in dynamics of spore seasons are driven by meteorological conditions, ordination methods were applied. Canonical correspondence analysis was used to explore redundancy among the predictors (meteorological parameters). Prior to ordination analyses, the data were log(x)-transformed. Concentrations of Alternaria and Cladosporium spores were significantly higher in Szczecin comparing to Cracow, but it was also observed the decreasing trend in the spore concentrations in Szczecin. As regards temperature, it was higher in Cracow and was still increasing in the studied years. Relative humidity and wind velocity were significantly lower in Cracow. In Szczecin meteorological conditions did not explain changes in spore season characteristics (insignificant redundancy analysis models), while in Cracow’s redundancy analysis models indicated that spore season parameters were in over 40 % determined by meteorological conditions, mainly air temperature and wind velocity. If they increase, the peak value, total number of spores and their average concentrations in a season will also increase.     

Hybridization success is largely limited to homoploid <Emphasis Type="Italic">Prunus</Emphasis> hybrids: a multidisciplinary approach

Prunus fruticosa is a rare shrub occurring in Eurasian thermophilous forest-steppe alliances. The species frequently hybridizes with cultivated Prunus species in Europe (allochthonous tetraploid P. cerasus and partly indigenous diploid P. avium). Propidium iodide flow cytometry, distance-based morphometrics, elliptic Fourier analysis and embryology were employed to evaluate the extent of hybridization in six Slovak populations. Flow cytometric analyses revealed three ploidy levels: diploid (P. avium), triploid (P. × mohacsyana) and tetraploid (P. fruticosa, P. × eminens and P. cerasus). In addition, P. fruticosa and P. cerasus, at the tetraploid level, were found to differ in absolute genome size. An embryological evaluation suggested the existence of a triploid block in P. × mohacsyana and significant potential for hybridization among tetraploid taxa (indicated also by a continuous distribution of genome size data and further mirrored by morphometrics). Although hybrids significantly differ in ploidy level and embryological characteristics, they are almost indistinguishable using morphological characters. Hybridization with P. cerasus thus turns out to be a significant threat to wild populations of P. fruticosa compared to the relatively weak influence of P. avium.     

Genome size and ploidy level among wild and cultivated <Emphasis Type="Italic">Prunus</Emphasis> taxa in Slovakia

2C DNA content and ploidy level variation of Prunus spinosa and closely related taxa together with Prunus domestica L. and Prunus insititia L. was studied in Slovakia. The aim of the study was to define genome sizes and find differences between closely related taxa within Prunus spinosa sensu lato mentioned in previous works. According to our results, investigated taxa can be divided into three groups according to ploidy level: Prunus spinosa, Prunus dasyphylla, Prunus ×fruticans, Prunus ×dominii and Prunus ×schurii are tetraploids, Prunus ×fechtneri is pentaploid, and P. domestica and P. insititia are hexaploids. Genome size differences within tetraploid taxa were relatively small (Prunus spinosa: 1.40?±?0.02, P. ×domini: 1.44?±?0.01, P. ×fruticans: 1.48?±?0.02, P. ×schurii: 1.44?±?0.02), but statistically significant. Although further research is needed, it seems that the concept of several taxa as product of hybridization between P. spinosa and cultivated plum species has been supported by our study.     

Atmospheric concentrations and intradiurnal pattern of <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> conidia in Tétouan (NW of Morocco)

Fungal spores of Alternaria and Cladosporium are ubiquitous components of both indoor and outdoor air samples and are the main causes of human respiratory allergies. Monitoring these airborne fungal spores during 2009–2014 was carried out by means of Hirst-type spore trap to investigate their airborne spore concentrations with respect to annual load, seasonality and overall intradiurnal pattern. Alternaria and Cladosporium spores are present throughout the year in the atmosphere of Tétouan, although they show seasonal variations. Despite important differences between years, their highest levels presented a first peak during spring and a higher second peak in summer or autumn depending on the year. The spore concentrations were homogeneously distributed throughout the day with slight increase of 7.6 and 3.7% on average between 12–14 and 14–16 h for Alternaria and Cladosporium, respectively. The borderline of 3000 sp/m³ of Cladosporium linked to the occurrence of allergic diseases was exceeded between 13 and 31 days. Airborne spores of Alternaria overcame the threshold value of 100 sp/m³ up to 95 days, suggesting that Cladosporium and Alternaria could be clinically significant aeroallergens for atopic patients.     

Early characterization of somatic hybrids from symmetric protoplast electrofusion of <Emphasis Type="Italic">Solanum pinnatisectum</Emphasis> Dun. and <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.

Variability of 31 somatic hybrids of Solanum pinnatisectum Dun. with Solanum tuberosum L. for leaf morphology, plant vigor, resistance to Phytophthora infestans, ploidy level, and cytoplasm type was evaluated in vitro. The composition of these somatic hybrids was as follows: [S. pinnatisectum Dun. (2n = 2x = 24; cytoplasmic type Wγ) + S. tuberosum L. (2n = 4x = 48; cytoplasmic type Tß)]. Based on leaf morphology and plant growth vigor, plants were divided into three groups, including plants close to tbr parent with unlobed leaves, small plants with scarcely dissected leaves, and vigorous plants with asymmetrically and pinnately lobed leaves. Nine of the somatic hybrids were found to be highly resistant to P. infestans. Somatic hybrids were either tetraploid or hexaploid, with hexaploids being predominant. The cytoplasm of somatic hybrids was either Tßγ or Wßγ, with Tßγ being more common. Overall, in contrast to leaf morphology and growth vigor, level of resistance to P. infestans was not related to either ploidy level or type of cytoplasm. These findings demonstrate that early in vitro selection of promising hybrids can be useful in breeding programs.     

Airborne pollen and fungal spores in Garki,Abuja (North-Central Nigeria)

The ambient atmosphere is dominated with pollen and spores, which trigger allergic reactions and diseases and impact negatively on human health. A survey of pollen and fungal spores constituents of the atmosphere of Garki, Abuja (North-Central Nigeria) was carried out for 1 year (June 1, 2011–May 31, 2012). The aim of the study was to determine the prevalence and abundance of pollen and fungal spores in the atmosphere and their relationship with meteorological parameters. Airborne samples were trapped using modified Tauber-like pollen trap, and the recipient solutions were subjected to acetolysis. Results revealed the abundance of fungal spores, pollen, fern spores, algal cysts and diatoms in decreasing order of dominance. The atmosphere was qualitatively and quantitatively dominated by pollen during the period of late rainy/harmattan season than the rainy season. Numerous fungal spores were trapped throughout the sampling periods among which Alternaria spp., Fusarium spp., Cladosporium spp. and Curvularia spp. dominated. These fungi have been implicated in allergic diseases and are dermatophytic, causing diverse skin diseases. Other pathogenic fungi found in the studied aeroflora were Dreschlera spp., Helminthosporium spp., Torula spp., Pithomyces spp., Tetraploa spp., Nigrospora ssp., Spadicoides spp., Puccinia spp. and Erysiphe graminis. Total pollen and fungal spores counts do not show significant correlation with meteorological parameters.     

Pollen analysis of spider web samples from Korba District,Chhattisgarh (central India): an aerobiological aspect

Pollen analyses of spider web samples, collected from the recently planted Tectona grandis (T. grandis, teak)-dominated tropical deciduous forest of Bhulsidih Village, Korba District (Chhattisgarh, central India), shed light on the relationship between the extant vegetation and pollen rain. The study revealed the dominance of pollen of herbs and trees, whereas shrubs, fern spores and algal remains are meagre. Among the tree taxa, Sapotaceae, Syzygium, Holoptelea, Lannea coromandelica, Shorea robusta and Grewia are dominating with moderate to low and intermittent presence of Madhuca indica, Terminalia, Mitragyna, Schleichera, Anacardiaceae, Diospyros, Emblica officinalis and Flacourtia. However, the rest of the forest constituents are either not represented at all despite their presence in the floristics, which could be attributed to their low pollen productivity owing to entomophily as well as their poor pollen preservation pattern. On the other hand, the ground vegetation is represented by the very high frequency of grasses (Poaceae) along with Tubuliflorae, Chenopodiaceae/Amaranthaceae and Cerealia, however, Artemisia, Xanthium, Malvaceae, Caryophyllaceae and Justicia in moderate to lower values. Ferns, which occur abundantly along the adjoining stream banks, are marked by the sporadic retrieval of trilete spores that could be ascribed to the prevailing damp condition around the sampling provenance. The study, in addition to understanding the pollen–vegetation relationship, could also be helpful in aerobiological study, especially in assessing the allergenicity of various pollen grains/spores in the area of investigation, causing bronchial asthma, hay fever (allergic rhinitis/pollinosis), naso-bronchial allergy and other respiratory disorders along with conjunctivitis, contact dermatitis, eczema, food allergies and other health disorders.     

Monitoring of anamorphic fungal spores in Madeira region (Portugal), 2003–2008

Seven years of aeromycological study was performed in the city of Funchal with the purpose to determine the anamorphic spore content of this region and its relationship to meteorological factors. The sampling was carried out with a Hirst-type volumetric spore trap following well-established guidelines. A total of 17,586 anamorphic fungal spores were recorded during the studied period, attaining an annual average concentration of 2931 spores m^?3. Anamorphic fungal spores were observed throughout the year, although the major peaks were registered during spring (April–June) and autumn period (September–November). The lowest spore levels were recorded between December and February months. Over 14 taxa of anamorphic fungal spores were observed with Cladosporium being the most prevalent fungal type accounting for 78 % of the total conidiospores. The next in importance was Alternaria (5.4 %), Fusarium (4.7 %), Torula (3.9 %) and Botrytis (1.9 %). Temperature was the meteorological parameter that favoured the most release and dispersal of the conidiospores, whereas rainfall revealed a negative effect. Despite the low concentration levels found in our region, the majority of the fungal types identified are described as potential aeroallergens. This study provides the seasonal variation of the conidiospores and the periods when the highest counts may be expected, representing a preventive tool in the allergic sensitization of the population.