Fine root production in three zones of secondary mangrove forest in eastern Thailand

Key message

High root productions, especially in the fine roots, estimated by ingrowth cores were confirmed in mangrove forests. The zonal variation in root production was caused by inundation regime and soil temperature.

Abstract

Mangrove forests have high net primary productivity (NPP), and it is well known that these trees allocate high amounts of biomass to their root systems. In particular, fine root production (FRP) comprises a large component of the NPP. However, information on root production remains scarce. We studied FRP in three zones (Avicennia, Rhizophora, and Xylocarpus) of a mangrove forest in eastern Thailand using ingrowth cores (0–30 cm of soil depth). The root biomass and necromass were periodically harvested from the cores and weighed during the one-year study. The FRP was determined by summation of the fine root biomass (FRB) and root necromass. The results showed that the FRB clearly increased in the wet and cool dry seasons. Magnitude of FRB in the Rhizophora and Xylocarpus zones was 1171.07 and 764.23 g/m²/30 cm, respectively. The lowest FRB (292.74 g/m²/30 cm) was recorded in the Avicennia zone locating on the river edge where there is a greater frequency of inundation than the other zones. Root necromass was high in the Rhizophora and Xylocarpus zones, and accumulated noticeably when soil temperatures rapidly declined during the middle of the wet season to cool dry season. However, root necromass in the Avicennia zone varied within a small range. We attributed the small accumulation of root necromass in the Avicennia zone to the relative high soil temperature that likely caused a high root decomposition rate. The average FRP (3.403–4.079 ton/ha/year) accounted for 74.4, 81.5, and 92.4 % of the total root production in the Avicennia, Rhizophora, and Xylocarpus zone, respectively. The root production and causative factors (i.e., soil temperature and inundation regime) are discussed in relation to the carbon cycle of a mangrove forest.

     

Fingerprinting by amplified fragment length polymorphism (AFLP) and barcoding by three plastidic markers in the genus <Emphasis Type="Italic">Wolffiella</Emphasis> Hegelm

Amplified fragment length polymorphism (AFLP) fingerprinting and three different plastidic DNA regions (rpl16, rps16, atpF-atpH) were used to investigate species identity in the genus Wolffiella. For this purpose, clones (67 in total) belonging to all ten species were selected. Almost all the species were represented by more than one clone. The fingerprinting technique, AFLP, clearly distinguished the species, W. caudata, W. gladiata, W. neotropica, W. rotunda, and W. welwitschii. Apart from confirming the molecular identity of these five species, the plastidic markers could delineate two additional species, W. hyalina and W. denticulata, although the conclusion concerning the latter is restricted by the availability of only one clone. The efficiency of the plastid-derived markers in identifying the number of species-specific clusters followed the sequence rps16 > rpl16 > atpF-atpH. The species W. lingulata, W. oblonga, and W. repanda could not be identified by any of the molecular methods presented here, but could be strictly defined on a morphological basis. In several clones, high amounts of genetic admixtures between different species were detected. Further, simulation studies demonstrated that these clones are genetic hybrids. This might be one of the obstacles in molecular identification of species in the genus Wolffiella.     

Cell culture system versus adventitious root culture system in Asian and American ginseng: a collation

Panax ginseng and Panax quinquefolius of Panax genus are valuable as health foods as well as pharmaceuticals for the treatment of cancer, diabetes and ageing as these plants possess saponins. In the current study, Cell and adventitious root cultures of P. ginseng and P. quinquefolius were investigated for the biomass, cell division, saponin content and ginsenosides profile from four lines namely P. quinquefolius (AM), P. ginseng mountain (Mt.) Baekdu line, P. ginseng Cheong-sol line (CS) and P. ginseng CBN line (CBN) with the objective of comparing cell and adventitious root systems to check their efficacy for the production of ginseng saponins. Additionally, genes related to ginsenoside biosynthesis were also analyzed concerning to cell and adventitious root lines. The results indicated that various cell lines were better in multiplication and growth compared to adventitious root lines. However, adventitious root lines showed higher accumulation of dry biomass (1.5–2 fold) than that of cell lines. CS adventitious root line showed higher saponin content and ginsenoside productivity (10.48 mg·g^?1 DW, 12.88 mg·L^?1, respectively) than that of CS cell line (9.50 mg·g^?1 DW, 2.39 mg·L^?1, respectively). Especially, Rd ginsenoside productivity of CS adventitious root line recorded fourfold higher than CS cell line. Genes which are related to ginsenoside biosynthesis such as P. ginseng squalene synthase (PgSS2), P. ginseng squalene epoxidase (PgSE2), P. ginseng protopanaxadial synthase (PgPPDS) and P. ginseng protopanaxatriol synthase (PgPPTS) were analyzed by real time quantitative polymerase chain reaction to support ginsenoside production. The adventitious root culture system described in this study is useful system for biomass and ginsenoside production.     

<Emphasis Type="Italic">In vitro</Emphasis> propagation and agronomic performance of regenerated chili pepper (C<Emphasis Type="Italic">apsicum</Emphasis> spp.) plants from commercially important genotypes

The application of modern biotechnology for improvement of chili pepper productivity requires an efficient in vitro plant regeneration protocol. In this study, a reliable protocol was developed for the in vitro regeneration of four types of chili, Capsicum annuum var. annuum (Jalapeño and Serrano), C. annuum var. glabriusculum/aviculare (Piquin), and C. chinense (Habanero) by direct organogenesis using three different explants (cotyledon, hypocotyls, and embryo) and three induction media. All evaluated culture media promoted the formation of adventitious shoots. When embryos or hypocotyls were used as explants, morphologically normal adventitious shoots developed, while culturing cotyledons resulted in nonelongating rosette-shaped shoots. The highest in vitro regeneration efficiency (14.6 shoots per explant) was achieved when Habanero chili hypocotyls were grown on Murashige and Skoog medium containing 1.7 μM indole-3-acetic acid and 22.2 μM N⁶-benzyladenine. This regeneration rate is higher than that obtained in previous reports. Regenerated plants were ready to be transferred to the greenhouse 13 wk after the explant culture. An evaluation carried out under greenhouse conditions showed differences in agronomic performance between in vitro regenerated plants and plants developed from seeds with the magnitude of the differences depending on the genotype being studied.     

The interactive effects of created salt marsh substrate type,hydrology, and nutrient regime on <Emphasis Type="Italic">Spartina alterniflora</Emphasis> and <Emphasis Type="Italic">Avicennia germinans</Emphasis> productivity and soil development

Recent salt marsh and barrier island restoration efforts in the northern Gulf of Mexico have focused on optimizing self-sustaining attributes of restored marshes to provide maximum habitat value and storm protection to vulnerable coastal communities. Salt marshes in this region are dominated by Spartina alterniflora and Avicennia germinans, two species that are valued for their ability to stabilize soils in intertidal salt marshes. We conducted a controlled greenhouse study to investigate the influences of substrate type, nutrient level, and marsh elevation on the growth and biomass allocation of S. alterniflora and A. germinans, and the consequent effects on soil development and stability. S. alterniflora exhibited optimal growth and survival at the lowest elevation (? 15 cm below the water surface) and was sensitive to high soil salinities at higher elevations (+ 15 cm above the water surface). A. germinans performed best at intermediate elevations but was negatively affected by prolonged inundation at lower elevations. We found that although there was not a strong effect of substrate type on plant growth, the development of stressful conditions due to the use of suboptimal materials would likely be exacerbated by placing the soil at extreme elevations. Soil shear strength was significantly higher in experimental units containing either S. alterniflora or A. germinans compared to unvegetated soils, suggesting that plants effectively contribute to soil strength in newly placed soils of restored marshes. As marsh vegetation plays a critical role in stabilizing shorelines, salt marsh restoration efforts in the northern Gulf of Mexico and other storm impacted coasts should be designed at optimal elevations to facilitate the establishment and growth of key marsh species.     

Age-based demography and reproductive biology of three <Emphasis Type="Italic">Epinephelus</Emphasis> groupers, <Emphasis Type="Italic">E. polyphekadion,E. tauvina,</Emphasis> and <Emphasis Type="Italic">E. howlandi</Emphasis> (Serranidae), inhabiting coral reefs in Okinawa

The demography and reproductive biology of three Epinephelus groupers (Serranidae), namely E. polyphekadion, E. tauvina, and E. howlandi in the Yaeyama Islands, Okinawa, were examined based on age assessment using otoliths and gonadal histology. The maximum ages for these three species were 26 year, 23 year, and 17 year. The von Bertalanffy growth functions were also determined for each species. The size and age at 50% female maturity were estimated to be 358 mm in total length (TL) and 6.0 year for E. polyphekadion, 371 mm TL and 6.7 year for E. tauvina, and 327 mm TL and 4.1 year for E. howlandi, respectively. Significant differences between the sexes in size and age frequencies were found in all three species, with males being larger and older than females, or transitional individuals. These results strongly indicated that the population of these three grouper species showed monandric protogynous hermaphroditism. The sex ratios of E. polyphekadion and E. tauvina were biased in favor of females, but that of E. howlandi was equivalent between sexes. The relative sizes of ripe testes indicated that the intensity of sperm competition varied among species suggesting different mating system of each species. Reproductive seasonality was similar among species, with active vitellogenesis coinciding with the annual rise in water temperature. The active spawning period was determined to be between April and May for E polyphekadion, in May for E. howlandi, and from March to June for E. tauvina.     

Domestic pig uprooting emerges as an undesirable disturbance on vegetation and soil properties in a plateau wetland ecosystem

Pig disturbances are recognized as key factors influencing the structure of ecosystems. Cage-free domestic pig (Sus scrofa domestica) searching for food by uprooting vegetation is emerging as a threat to wetlands located in Qinghai-Tibet Plateau. As a unique and fragile ecosystem, the ecological impacts of pig uprooting (PR) here remain unclear. Here, we examined vegetation and soil properties under PR in the meadows of a plateau wetland, Napahai. Quadrat surveys and sampling were taken during the late growing season (September) of 2014 at three sites: one was seasonally flooded (wet meadow) and the other two were unflooded (dry meadows). Compared to controls (pig-undisturbed patches), plant biomass and density decreased (p < 0.001), while soil bulk density increased (p < 0.05) for all sites under PR. In addition, divergent responses to pig disturbances were observed in different sites. In the wet meadow, PR caused a shift in vegetation from Blysmus sinocompyessus, a dominant perennial herb towards the annual hydrophyte Polygonum hydropiper. In the two dry meadows, the dominant species remained unchanged, but nutrients stored in soils were severely reduced by PR, accelerating the soil impoverishment when compared to the wet meadow. Overall, PR impacts on local ecosystems are largely dependent on the moisture characteristics of micro-habitats, and proper management should be taken to counteract ecosystem degradation, especially in dry meadows.     

Effect of cold stratification on seed germination in <Emphasis Type="Italic">Solidago</Emphasis> × <Emphasis Type="Italic">niederederi</Emphasis> (<Emphasis Type="Italic">Asteraceae</Emphasis>) and its parental species

In this study, we investigated the influence of cold stratification on seed germination in S. × niederederi, a hybrid between the North American S. canadensis and the European S. virgaurea, using fruit samples collected in 2016 in Poland. We aimed to test the hypothesis that the low temperature exposure decreases the final percentage and speed of seed germination in the hybrid and its parental species. For each species, sets of 100 achenes in three replications were mixed with dry sand and stored in Petri dishes in darkness for 12 weeks, at ?18 °C and?+?4 °C, and?+?25 °C. The seeds were incubated for 21 d at room temperature (+25 °C), under the 12 h photoperiod (630 lx). We showed a lack of significant differences in: (i) the final percentage of germinated seeds of studied species stored at the same conditions, (ii) the final percentage of germinated seeds between the applied stratification conditions in the hybrid and its parental species, and (iii) the mean values of Timson’s index, mean germination time, and coefficient of velocity of germination between the stratification conditions in each species. The statistically significant inter-specific differences in the mean germination time parameter after the +25 °C treatment suggest that the seeds of S. × niederederi are able to germinate faster than the seeds of its parental species. However, to improve our knowledge of naturalization and invasion abilities of S. × niederederi by sexual reproduction, the seed germination and seedling survival of the hybrid should be tested in the field.     

Management of <Emphasis Type="Italic">Nymphoides peltatum</Emphasis> using water level fluctuations in freshwater lakes of Kashmir Himalaya

Lakes have an esthetic significance that is particularly important for attracting tourism. In this context, it is often preferable for lakes to have clear water, so many lake managers attempt to achieve clear lake water by various means. However, the lakes of Kashmir Himalaya are undergoing several complex ecological changes due to, for example, increasing tourism, overfishing, and intensive agriculture, which are making these lakes less clear. One such change is the vigorous growth and development of aquatic weeds in the shallow-water areas of Kashmir Himalayan lakes. We thus, investigated the response of Nymphoides peltatum, a rapidly multiplying clonal species, to water depth, in order to determine whether water depth can be used to control the spread of this proliferating macrophyte. Different traits of the given plant species, such as the mean number of ramets, were significantly higher (F = 55.412, p = 0.000) at depth zone D1 (0–100 cm) than at depth zones D2 (101–200 cm) and D3 (201–300 cm). In all of the lakes, mean spacer length—a tool for facilitating plant spread—was observed to be significantly higher (F = 45.890, p = 0.000) at lower water levels (0–100 cm). Also, the reproductive structures (flowers) of N. peltatum showed significant variation with depth (F = 51.909, p = 0.000) and with the lake examined (F = 9.909, p = 0.001). Thus, the results obtained during the present study indicate the importance of water depth in the management of N. peltatum in various Kashmir Himalayan lakes.     

Interannual variation in rainfall,drought stress and seedling mortality may mediate monodominance in tropical flooded forests

Flood tolerance is commonly regarded as the main factor explaining low diversity and monodominance in tropical swamps. In this study we examined seedling mortality in relation to seasonality, i.e., flooding versus drought, of the dominant tree species (Prioria copaifera), and three associated species (Pterocarpus officinalis, Carapa guianensis and Pentaclethra macroloba), in seasonally flooded forests (SFF) in Darien, Panama. Seedling mortality differed among species, years and seasons. Prioria seedlings experienced the lowest overall mortality, and after 3 years many more Prioria seedlings remained alive than those of any of the associated species. In general, within species, larger seedlings had greater survival. Seed size, which can vary by close to 2 orders of magnitude in Prioria, had a confounding effect with that of topography. Large-seeded Prioria seedlings experienced 1.5 times greater mortality than small-seeded seedlings, as large-seeded Prioria seedlings were more likely to be located in depressions. This finding suggests that seed size, plant size and topography are important in understanding SFF regeneration. For all species, seedling mortality was consistently greater during the dry season than during flooding. For Prioria, dry season seedling mortality was correlated with drought stress, that is, high mortality during the long El Niño dry season of 1998 and the normal dry season of 2000, but very low dry season mortality during the mild dry season of 1999. Prioria’s ability to dominate in seasonally flooded forest of Central America is partly explained by its low drought-related mortality in comparison to associated species.     

Construction of genetic transformation system of <Emphasis Type="Italic">Salix mongolica</Emphasis>: in vitro leaf-based callus induction,adventitious buds differentiation,and plant regeneration

Songnen meadow grassland is a typical saline-alkaline land majorly comprised of carbonate soil. Salix mongolica, a woody species with high adaptability to carbonate soil, is an important supplementary feed in the grassland. Therefore, it is necessary to cultivate new varieties of S. mongolica by using genetic engineering methods to reveal the functions of the plant’s related genes and to construct a plant regeneration and genetic transformation system. In this study, we used leaves of S. mongolica as the explants for induction of leaf-based callus, differentiation of adventitious buds and rooting of adventitious by adding different ratios of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzyl aminopurine and naphthaleneacetic acid into the Murashige and Skoog medium. Under the screening conditions of 7.5 mg L^?1 hygromycin B and transformation period of 2–5 min using a specific Agrobacterium containing pCXSN-gus plasmids infection concentration (OD_λ600?=?0.5), we obtained transgenic strains. PCR detected exogenous gus gene integrated into the chromosome of S. mongolica, Southern blot analysed the T0 transgenic strains single copy inserted into the chromosome, Northern hybridization signals indicated that gus gene mRNA was expressed in the five contemporary transgenic strains. The infected callus, adventitious buds, and regenerated plants displayed a blue color through detection by GUS staining, which reflected the activity of ß-glucuronidase enzyme. This result demonstrated the successful establishment of an Agrobacterium-mediated genetic transformation system from the callus (S. mongolica leaf as a transformation receptor).     

Survey of Philippine coffee beans for the presence of ochratoxigenic fungi

In 2012 to 2014, Philippine green coffee beans from Coffea arabica in Benguet and Ifugao; Coffea canephora var. Robusta in Abra, Cavite, and Ifugao; and Coffea liberica and Coffea excelsea from Cavite were collected and assessed for the distribution of fungi with the potential to produce ochratoxin A (OTA). The presence of fungal species was evaluated both before and after surface sterilization. There were remarkable ecological and varietal differences in the population of OTA-producing species from the five provinces. Aspergillus ochraceus, A. westerdijkiae, and Penicillium verruculosum were detected from Arabica in Benguet and Ifugao while Aspergillus carbonarius, Aspergillus niger, and Aspergillus japonicus were isolated in Excelsa, Liberica, and Robusta varieties from Abra, Cavite, and Davao. Contamination by Aspergillus and Penicillium species was found on 59 and 19 %, respectively, of the 57 samples from five provinces. After disinfection with 1 % sodium hypochlorite, the levels of infection by Aspergillus and Penicillium fell to 40 and 17 %, respectively. A total of 1184 fungal isolates were identified to species level comprising Aspergillus sections Circumdati (four species), Clavati (one), Flavi (one), Fumigati (one), Nigri (three), and Terrie (one). Within section Circumdati, 70 % of A. ochraceus produced OTA as high as 16238 ng g^?1 while 40 % of A. westerdijkiae produced maximum OTA of 36561 ng g^?1 in solid agar. Within section Nigri, 16.76 % of A. niger produced OTA at the highest 18439 ng g^?1, 10 % of A. japonicus at maximum level of 174 ng g^?1, and 21.21 % of A. carbonarius yielded maximum OTA of 1900 ng g^?1. Of the 12 species of Penicillium isolated, P. verruculosum was ochratoxigenic, with a maximum OTA production of 12 ng g^?1.     

The internal morphology of <Emphasis Type="Italic">Acoscinopleura</Emphasis> Voigt, 1956 (Cheilostomata,Bryozoa) from the Campanian–Maastrichtian of Central and Eastern Europe

Coscinopleurid cheilostome bryozoans are widespread in Latest Cretaceous sediments throughout the whole Boreal Chalk Sea. Despite having many polymorphs that can readily be distinguished, intraspecific plasticity is high and polymorph morphology shows only little variation over time. This significantly hampers taxon differentiation in coscinopleurids. In this study, we revise type material of three coscinopleurid species, Acoscinopleura foliacea (Voigt, 1930), A. fallax Voigt, 1956 and A. rugica Voigt, 1956, from the Maastrichtian of northern Germany using combined scanning electron microscopy and X-ray microtomography. The three species are morphologically very similar and were distinguished by the original author only in the shape and position of peripheral caverns inside their cryptocyst and in the position of vibracular polymorphs. X-ray microtomography allowed study of the internal morphology of the species and provided additional parameters that can be used for species differentiation. Septula, arch-like and channel-like cavities and microcavities could be identified inside the calcified walls. While the original identity of the type material of A. foliacea and A. rugica remains unchanged, the type material of A. fallax is shown to belong to three different species: A. fallax, A. occulta sp. nov. and A. dualis sp. nov. Additionally, hitherto-unstudied material from the late Campanian and Maastrichtian of northern Germany and Belarus is described as A. crassa sp. nov. and A. albaruthenica sp. nov.     

High responsiveness in <Emphasis Type="Italic">de novo</Emphasis> shoot organogenesis induction of <Emphasis Type="Italic">Passiflora cristalina</Emphasis> (Passifloraceae), a wild Amazonian passion fruit species

The aim of the present study was to establish a regeneration system via de novo organogenesis from different types of non-meristematic explants of Passiflora cristalina. Leaf, hypocotyl, root segments, cotyledons, and endosperm of P. cristalina seeds were inoculated in Murashige and Skoog (MS)-basal medium, supplemented with different concentrations of 6-Benzyladenine (BA), Thidiazuron (TDZ), or Kinetin (KIN). BA was found to be the most efficient cytokinin in induction of de novo organogenesis from most the explants used in the study. The highest frequencies of adventitious bud formation in the hypocotyl and cotyledon explants were observed in medium supplemented with 1.0 mg L^?1 BA. For leaf and endosperm segments, the best concentration was 2.0 mg L^?1 BA; while for root segments, the highest mean values were observed with 1.0 mg L^?1 KIN. The different morphogenetic responses obtained from each explant source were characterized using light microscopy. P. cristalina revealed a remarkable organogenic potential, with superior production of adventitious shoots compared with the other Passiflora species evaluated elsewhere. These results will be helpful to establish a reproducible and reliable micropropagation protocol, as well as to implement conservationist and biotechnological-based genetic breeding strategies for this wild Passiflora species.     

Application of the LAMP assay for the detection of the Argentine ant, <Emphasis Type="Italic">Linepithema humile</Emphasis> (Hymenoptera: Formicidae), from captures of pan traps

We applied the loop-mediated isothermal amplification (LAMP) assay to monitor invasions of Linepithema humile (Mayr), the Argentine ant, a notorious invasive insect worldwide. Species-specific LAMP primers were designed on the basis of the partial sequence of the cytochrome c oxidase subunit I region of L. humile. The species specificity and sensitivity of these primers were determined in the laboratory and considered adequate for practical use. We also confirmed that the assay successfully detected L. humile from captures of pan traps, which contained L. humile and several non-target ant species. The assay detected the target species even when the captures contained only a leg or an antenna. Since the LAMP assay is simple and rapid, this assay will contribute to the early detection and accurate identification of L. humile.     

Accumulation of Heavy Metals in Some Marine Fisheries Resources Collected from Gulf of Mannar Marine Biosphere Reserve,Southeast Coast of India

Concentrations of toxic metals viz. mercury (Hg), cadmium (Cd) and lead (Pb) were evaluated in four species of fishes (Sardinella longiceps, Selaroides leptolepis, Epinephelus quoyanus and Lethrinus lentjan), one species of shrimp (Penaeus semisulcatus) and one species of crab (Portunus sanguinolentus) sampled from Thoothukudi, Keelakarai and Veerapandian pattinam of Gulf of Mannar, Southeast coast of India. Results revealed accumulation of these metals in the following order Hg > Cd > Pb. Hg concentration was found to be higher in Po. sanguinolentus followed by E. quoyanus, Pe. semisulcatus and L. lentjan however, the same was absent in Sa. longiceps and Se. leptolepis. Cd concentration was recorded in decreasing order in Po. sanguinolentus > Pe. semisulcatus > L. lentjen > E. quoyanus > Sa. longiceps > Se. leptolepis. Pb was detectable only in four species. Results of One-way ANOVA revealed significant variations (p < 0.05) in accumulation of Cd in Sa. longiceps, Se. leptolepis and Pe. semisulcatus and Hg in E. quoyanus, L. lentjan and Po. sanguinolentus. Variations noted in Pb were not statistically significant throughout.     

Exploring virulence of new and less studied species of <Emphasis Type="Italic">Metarhizium</Emphasis> spp. from Brazil for two-spotted spider mite control

The two-spotted spider mite Tetranychus urticae is an important pest of strawberry crops in Brazil and many other countries. Focus for biocontrol studies involving entomopathogenic fungi has been on three species from the genus Metarhizium: M. anisopliae sensu stricto (s.s.), M. brunneum and M. robertsii. Also, the species Beauveria bassiana has been studied for spider mite control and one isolate (ESALQPL63) is commercially available in Brazil. New and undescribed Metarhizium species have been found recently in Brazil and provide a pool of isolates with potential for biocontrol in Brazil and probably also elsewhere. The mortality of adult females of T. urticae when exposed to four new Brazilian species of Metarhizium was compared to the mortality when exposed to M. anisopliae s.s., M. brunneum, M. pingshaense, M. robertsii and Beauveria bassiana ESALQPL63. Fungal suspensions were sprayed onto mites at 10⁷ conidia/mL with 0.05% Tween 80 in laboratory bio-assays. We measured total mortality and percentage sporulating cadavers 10 days after exposure and calculated median lethal time (LT₅₀). The lowest LT₅₀ (4.0 ± 0.17) was observed for mites treated with Metarhizium sp. Indet. 1 (ESALQ1638), which also performed well with respect to mortality after 10 days and capacity to sporulate from cadavers. Among the other little studied species tested, M. pingshaense (ESALQ3069 and ESALQ3222) and Metarhizium Indet. 2 (ESALQ1476) performed well and were comparable to B. bassiana (ESALQPL63). The new Metarhizium isolates and species thus showed potential for biological control.     

Detection and Quantification of <Emphasis Type="Italic">Vibrio cholerae,Vibrio parahaemolyticus</Emphasis>, <Emphasis Type="Italic">and Vibrio vulnificus</Emphasis> in Coastal Waters of Guinea-Bissau (West Africa)

V. cholerae, V. parahaemolyticus, and V. vulnificus are recognized human pathogens. Although several studies are available worldwide, both on environmental and clinical contexts, little is known about the ecology of these vibrios in African coastal waters. In this study, their co-occurrence and relationships to key environmental constraints in the coastal waters of Guinea-Bissau were examined using the most probable number-polymerase chain reaction (MPN-PCR) approach. All Vibrio species were universally detected showing higher concentrations by the end of the wet season. The abundance of V. cholerae (ISR 16S-23S rRNA) ranged 0–1.2 × 10⁴ MPN/L, whereas V. parahaemolyticus (toxR) varied from 47.9 to 1.2 × 10⁵ MPN/L. Although the presence of genotypes associated with virulence was found in environmental V. cholerae isolates, ctxA+ V. cholerae was detected, by MPN-PCR, only on two occasions. Enteropathogenic (tdh+ and trh+) V. parahaemolyticus were detected at concentrations up to 1.2 × 10³ MPN/L. V. vulnificus (vvhA) was detected simultaneously in all surveyed sites only at the end of the wet season, with maximum concentrations of 1.2 × 10⁵ MPN/L. Our results suggest that sea surface water temperature and salinity were the major environmental controls to all Vibrio species. This study represents the first detection and quantification of co-occurring Vibrio species in West African coastal waters, highlighting the potential health risk associated with the persistence of human pathogenic Vibrio species.     

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.