SEARCH CONTENT

You are looking at 1 - 10 of 8,086 items :

  • Plant Science x
Clear All

Abstract

Caffeine is present in coastal environments worldwide and there is a need to assess its impact on marine organisms. Here, we exposed two species of ecologically important marine macroalgae (Chondrus crispus and Codium fragile subsp. fragile) to a suite of caffeine concentrations and measured their response. Caffeine concentrations of 10–100 ng L−1 had no significant effect on the growth rate or photosynthetic efficiency of either algae. Extremely high concentrations (100–200 mg L−1), which may occur acutely, produced sublethal effects for both species and mortality in C. fragile subsp. fragile. Our results highlight the need to understand how caffeine impacts marine species.

Abstract

The genus Opephora currently contains 37 species and 27 infraspecific taxa. However, the existing literature reveals a wide morphological diversity and the need to establish defining characters to circumscribe the genus as a cohesive and, perhaps, monophyletic group. The type material of Opephora pacifica, the generitype, is analysed. We emend the description of both the species and the genus, the latter also based on published light and scanning electron microscopy observations of closely related species. After review of the available literature, we determined that currently only two species can be ascribed with certainty to the genus Opephora: O. pacifica and O. marina. Based on available literature, it is highly likely that O. fragilarioides also belongs to this genus. We present a table with all known species and infraspecific taxa and make comments regarding their recent transfer to other genera, their current accepted nomenclature, and the genus to which they should probably be ascribed pending the collection of further information.

Abstract

In this work, we identified non-crustose invasive (Codium fragile subsp. fragile) and native Codium spp. (Codium tomentosum and Codium vermilara) in the central Cantabrian Sea using DNA barcoding (tufA and rbcL genes). We designed a new FCOtufA genetic marker for identifying Codium spp. in fresh and herbarium material. The tufA and rbcL sequences revealed three different single haplotypes for each of the species and a lack of intraspecific genetic diversity. The FCOtufA genetic marker revealed one new haplotype of C. fragile within the native region (South Korea), suggesting the possibility of higher genetic diversity in the donor region of this invasive species.

Abstract

Three new non-geniculate coralline algal species from South Africa are described that were passing under the misapplied name, Spongites yendoi. Based on plastid encoded DNA sequences from psbA and rbcL markers, these species belong in the subfamily Chamberlainoideae. The DNA sequences, supported by the morpho-anatomical character of tetrasporangial conceptacle roof development, placed all three species in the genus Chamberlainium and not Pneophyllum, the only other genus in Chamberlainoideae. In addition to the diagnostic DNA sequences, Chamberlainium capense sp. nov., C. glebosum sp. nov. and Chamberlainium occidentale sp. nov. may be distinguished by a combination of habit, habitat, geographic distribution, and several morpho-anatomical features. Biogeographically all three species are found in the Benguela Marine Province of South Africa, with C. occidentale being the most widespread. Chamberlainium glebosum also has a wide, but disjunct distribution and C. capense is another South African endemic non-geniculate coralline, whose range is restricted to a 43 km stretch of coastline. Thus far, DNA sequences from type specimens of non-geniculate corallines show that only those species whose type localities are from South Africa are correctly applied; all other non-geniculate coralline names are likely misapplied in South Africa.

Abstract

Phosphorus is a key macronutrient in macroalgal physiology, including carbohydrate anabolism. To determine the effects of phosphorus on different physiological parameters, we cultivated Ulva fasciata specimens from distinct localities (upwelling and non-upwelling sites) in the presence of different phosphate concentrations (0, 2, and 4 µM PO43). After 15 days, growth rates were similar (approx. 12% day−1) and carbohydrate contents had increased in individuals from both sites. In individuals from the upwelling site, carbohydrate contents were high in all treatments (71% dry mass), whereas non-upwelling site individuals cultivated under the highest phosphate concentration showed the lowest carbohydrate content (46% DM). Nevertheless, we observed higher rates of phosphorus uptake in individuals from the non-upwelling site cultivated under the highest phosphate concentration, indicating a stress response to elevated nutrient concentrations. Individuals from both sites cultivated with phosphate maintained healthy photosystems over the experimental period (F v/F m = 0.788), whereas those cultivated in the absence of phosphate showed evidence of photosystem impairment, as indicated by a progressive decline in maximum quantum yield. Altogether, our results indicate that site origin and phosphate concentration influence the carbohydrate content in U. fasciata and that individuals from sites with broad environmental variation, such as upwelling events, can show higher productivity.

Abstract

Unicellular algae have evolved to express many forms of high-affinity phosphate transporters, and homologs of these proteins are broadly distributed in yeast, fungi, higher plants, and vertebrates. In this report, an effort has been made to characterize such a transporter gene, StPHO, in the marine diatom Skeletonema tropicum. The primers used for polymerase chain reaction were designed by referring to a homologous gene in a prasinophyte, and the full-length (1692 bp) cDNA of StPHO was then cloned and sequenced. Sequence alignments and secondary structure prediction indicated that StPHO is a gene that encodes a type III Na+/Pi cotransporter (SLC20 family). To study the function of StPHO, specific concentrations of inorganic phosphate (Pi) were used to alter the physiological status of S. tropicum. In each treatment, samples were collected for the measurements of StPHO mRNA, [PO4 3−], cell abundance, the maximal photochemical efficiency of photosystem II (F v/F m), and alkaline phosphatase activity (APA). The results indicated that the ambient [PO4 3−] strongly affected the population growth and related physiological parameters of S. tropicum. The transcription of StPHO was fully repressed when the [PO4 3−] was greater than 1 μM but increased approximately 100-fold when the ambient [PO4 3−] decreased to 0.02 μM. Within this [PO4 3−] range, the regression equations are Y = −0.6644X + 0.9034 and Y = −0.5908X + 0.8054 for Pi-starved and Pi-limited treatments, respectively. This trend of gene expression suggested that StPHO plays an important role in the uptake of [PO4 3−], and StPHO may serve as a useful molecular biomarker for Pi-stressed diatom populations in marine ecosystems.

Abstract

China aster and gaillardia are flowering plants with high economic importance in floriculture. In the present investigation, response of China aster and gaillardia seedlings to inoculation with the arbuscular mycorrhizal fungus Funneliformis mosseae + the plant growth-promoting rhizobacterium Bacillus sonorensis was studied by growing in multipots (pro trays). The germination percentage and plant growth parameters: length of shoots, roots and whole seedlings, stem diameter, biovolume index, plant strength, vigor index, dry weight and nutrient uptake, were analyzed 60 days after sowing. The microbial parameters, mycorrhizal root colonization and spore count, and the population of B. sonorensis in the substrate were also determined. The results brought out that growth of inoculated seedlings was significantly improved as compared to uninoculated seedlings. Based on the plant growth and microbial parameters studied, it was concluded that inoculating the substrate in pro trays with the microbial consortium results in producing vigorously growing seedlings.

Abstract

Fungal diseases are a persistent problem in the cultivation of white button mushrooms (Agaricus bisporus). The chemical control of pathogens is becoming less effective and less desirable, so new ways to limit these infections are urgently required. What is more, the disease is mostly controlled through cultural practices and good hygiene on mushroom farms. The aim of this study was to evaluate the fungicidal effects of ozone on fungal pathogens of common mushrooms. Experiments with the use of ozone gas for disinfection of growing rooms after the completion of the mushroom growing cycle were carried out. The fungicidal effectiveness of ozone fumigation was evaluated on the basis of the survival rate of the spores of the pathogens tested (Lecanicillium fungicola, Cladobotryum dendroides, Mycogone perniciosa, and Trichoderma aggressivum). Spore suspension was applied to aluminum plates and then was exposed to gaseous ozone. The assessment of the growth of colonies of fungal isolates obtained from infected surfaces was carried out using Rodac contact test plates. The results showed that L. fungicola, M. perniciosa, and C. dendroides isolates were sensitive to the gas ozone. In order to achieve 100% efficacy against Mycogone strains, a minimum of 6 hours of ozonation had to be applied, whereas for Cladobotryum strains, a minimum of 8 hours had to be applied. The Lecanicillium species was the most sensitive to ozonation because 30 minutes of ozonation was enough to gain 100% inhibition of its growth. No satisfactory results were obtained in the case of the pathogenic species of Trichoderma, regardless of the experimental conditions. Nevertheless, this study has demonstrated the usefulness of ozone as a disinfectant for empty growing rooms after the completion of the mushrooms’ cultivation cycle.

Abstract

Ex vitro rooting and acclimatization of two cultivars ‘Wojtek’ and ‘Zojka’ of blue honeysuckle (Lonicera caerulea var. kamtschatica Sevast.) were studied. To the ex vitro conditions were transferred rooted and unrooted shoots. The post-effect of auxin type and concentration as well as microcutting and soil substrate types were tested. The genetic stability of the plantlets in relation to the mother plants by using amplified fragment length polymorphism (AFLP) and inter simple sequence repeat (ISSR) markers has been also determined. It has been found that in vitro rooted cuttings of both cultivars showed a higher survival rate (max. 88%) and better growth and development when they were rooted on a medium containing a low auxin level (1.0 mg·dm−3). The results of the second experiment showed successful ex vitro rooting of blue honeysuckle shoots without auxin treatment. Higher ex vitro rooting and survival rate in the greenhouse have been observed for ‘Wojtek’ (max. 96%) than ‘Zojka’ (max. 88%). Better growth and development of shoots and roots were observed on peat alone or a mixture of peat and perlite as compared to a mixture of peat and sand. The micropropagated plantlets appeared similar to mother plants. Molecular analysis confirmed a high level of genetic stability of blue honeysuckle after 2 years of in vitro propagation. However, among the cultivars studied, ‘Wojtek’ showed slightly higher genetic stability than ‘Zojka’ (99.5% and 97.7%, respectively). For ‘Zojka’ plants, the degree of variation was comparable for AFLP and ISSR markers. For ‘Wojtek’, no polymorphism was detected using the ISSR analysis in contrast to the AFLP analysis.