Efficacy of In Vitro Lithium Chloride Treatments on Dermacentor reticulatus

Dermacentor reticulatus (Fabr., 1794) (Acari: Ixodidae) is parasite that spreads many diseases which are dangerous to humans and animals. Microelement lithium was found to have promising potential against the detrimental bee pest Varroa destructor. Furthermore, its effectiveness was confirmed against Dermanyssus gallinae, a major parasite of poultry, in vitro. In the present study, we investigated whether the efficacy of lithium chloride extends to other parasitic species, such as D. reticulatus. Our results revealed, for the first time, that the effectiveness of lithium chloride extends to D. reticulatus, confirmed to have 100% mortality at a relatively high minimum concentration of 1.38 M in vitro. The 24 h and 48 h median lethal concentration (LC₅₀) values proved to be 0.654 M and 0.481 M, respectively, for this species. Our pilot study may contribute to a better understanding of the properties of lithium ion. Furthermore, it may elicit further studies aiming to reveal whether the different environmental mineral conditions may influence the D. reticulatus population. Further studies might reveal whether lithium has any possible veterinary relevance.

Lithium Chloride Shows Effectiveness against the Poultry Red Mite (Dermanyssus gallinae)

The poultry red mite (Dermanyssus gallinae) is the main pest of poultry, causing severe problems by being a vector of several animal and human pathogens. The number of miticides is few, and their efficacy in practice implies problems of residues and resistance; therefore, the demand for a new and safe agent is constant. The present publication investigated the effectiveness of lithium chloride under in vitro conditions on poultry red mites. This chemical currently appears to be one of the most promising alternatives to study amongst potential applicants to treat varroosis, a fatal disease of honey bees. In Experiment I, the previously used experimental doses (5.52 M, 2.76 M, 1.38 M) on Varroa mites confirmed their in vitro activity on the poultry red mite. Three event times (uncontrolled movement, immobilisation and death) were recorded to base the response to treatment for each concentration. In Experiment II, the LD 50 value was calculated, i.e., the value at which 50% of the mites were killed by the treatment. This Experiment showed that the LD50 of lithium chloride = 0.265 M in the poultry red mite. It is to note that the study remained restricted to in vitro confirmation of lithium chloride's effectiveness on the parasite. Thus, further extensive studies are needed to decide whether it has any relevance in practice against D. gallinae, and also to assess potential residue problems that could affect poultry products.

Changes in Lithium Levels in Bees and Their Products Following Anti-Varroa Treatment

Simple Summary

Varroosis caused by the ectoparasitic mite Varroa destructor has been the biggest threat to managed bee colonies over recent decades. Chemicals available to treat the disease imply problems of resistance, inconsistent efficacy, and residues in bee products. Recently, alongside novel compounds to defeat the pest, lithium chloride has been found to be effective. In this study, we found that lithium treatments leave beeswax residue-free. The possibility of decontamination in adult bees, bee bread, and uncapped honey was revealed. On the other hand, ripe honey was found to be affected by lithium administered via feeding. Case studies are necessary to uncover the level of exposition in harvested honey to estimate its potential risk once it becomes a registered veterinary medicine.

Abstract

The biggest threat to beekeeping is varroosis caused by the mite Varroa destructor. Chemicals available to treat this fatal disease may present problems of resistance or inconsistent efficacy. Recently, lithium chloride has appeared as a potential alternative. To date, the amount of residue lithium treatments may leave in honeybee products is poorly understood. Honeybees were fed with 25 mM lithiated sugar syrup, which was used in earlier studies. The accumulation and elimination of the lithium were monitored in bees and their products for 22 days. Lithium concentration increased in the entire body of the bees to day 4 post-treatment and then recovered rapidly to the control level. Lithium exposure was found to affect uncapped honey in the short term (<16 days), but ripe (capped) honey measured at the end of the trial remained affected. On the other hand, lithium treatment left beeswax lithium-free. Based on these data, we propose that comprehensive research on harvested honey is needed to decide on the veterinary use of lithium.

Lithium chloride outperformed oxalic acid sublimation in a preliminary experiment for Varroa mite control in pre-wintering honey bee colonies

Since lithium salts were demonstrated to be very effective for the potential control of Varroa destructor, a highly detrimental parasite of honey bee (Apis mellifera), no studies have been reported on their comparison with any commonly used varroicides in commercial bee colonies. In this study we compared the effectiveness of lithium chloride to that of oxalic acid, a widely used miticide. The results of the present study confirm that lithium has superior efficacy to oxalic acid sublimation both as a main or a supplementary pre-wintering treatment at moderate infestation levels, restricted to certain pre-wintering conditions. Considering its easy implementation in apicultural practice and its twofold mode of action, trickling would be the preferred way of administration after the use of lithium salts as varroicides is authorised.

Contact Effect Contribution to the High Efficiency of Lithium Chloride Against the Mite Parasite of the Honey Bee

Lithium chemicals have been proven to be very effective in eradicating Varroa destructor, the detrimental parasite of the honey bee; however, little is known about the side effects on brood and long term consequences on the colony. Earlier, it was proposed that the action mechanisms of lithium chloride do not include the contact mode. Here, we investigate this question using a paper strip test to demonstrate the concentration-dependent effectiveness of lithium in the contact mode of action, confirming that it is also a contact agent against the Varroa mite. According to our knowledge, this is the first report on the high varroicidal effect of lithium in the contact mode of action. Our findings may open up possibilities for novel ways of treatment (e.g., the use of lithiated strips) in the event that lithium salts become legal for use in apiculture.

Mapping and DNA sequence characterisation of the Rysto locus conferring extreme virus resistance to potato cultivar 'White Lady'

Virus resistance genes carried by wild plant species are valuable resources for plant breeding. The Ry_sto gene, conferring a broad spectrum of durable resistance, originated from Solanum stoloniferum and was introgressed into several commercial potato cultivars, including ‘White Lady’, by classical breeding. Ry_sto was mapped to chromosome XII in potato, and markers used for marker-assisted selection in breeding programmes were identified. Nevertheless, there was no information on the identity of the Ry_sto gene. To begin to reveal the identification of Ry_sto, fine-scale genetic mapping was performed which, in combination with chromosome walking, narrowed down the locus of the gene to approximately 1 Mb. DNA sequence analysis of the locus identified six full-length NBS-LRR-type (short NLR-type) putative resistance genes. Two of them, designated TMV2 and TMV3, were similar to a TMV resistance gene isolated from tobacco and to Y-1, which co-segregates with Ry_adg, the extreme virus resistance gene originated from Solanum andigena and localised to chromosome XI. Furthermore, TMV2 of ‘White Lady’ was found to be 95% identical at the genomic sequence level with the recently isolated Ry_sto gene of the potato cultivar ‘Alicja’. In addition to the markers identified earlier, this work generated five tightly linked new markers which can serve potato breeding efforts for extreme virus resistance.

Different expression pattern of flowering pathway genes contribute to male or female organ development during floral transition in the monoecious weed Ambrosia artemisiifolia L. (Asteraceae)

The highly allergenic and invasive weed Ambrosia artemisiifolia L. is a monoecius plant with separated male and female flowers. The genetic regulation of floral morphogenesis is a less understood field in the reproduction biology of this species. Therefore the objective of this work was to investigate the genetic control of sex determination during floral organogenesis. To this end, we performed a genome-wide transcriptional profiling of vegetative and generative tissues during the plant development comparing wild-growing and in vitro cultivated plants. RNA-seq on Illumina NextSeq 500 platform with an integrative bioinformatics analysis indicated differences in 80 floral gene expressions depending on photoperiodic and endogenous initial signals. Sex specificity of genes was validated based on RT-qPCR experiments. We found 11 and 16 uniquely expressed genes in female and male transcriptomes that were responsible particularly to maintain fertility and against abiotic stress. High gene expression of homologous such as FD, FT, TFL1 and CAL, SOC1, AP1 were characteristic to male and female floral meristems during organogenesis. Homologues transcripts of LFY and FLC were not found in the investigated generative and vegetative tissues. The repression of AP1 by TFL1 homolog was demonstrated in male flowers resulting exclusive expression of AP2 and PI that controlled stamen and carpel formation in the generative phase. Alterations of male and female floral meristem differentiation were demonstrated under photoperiodic and hormonal condition changes by applying in vitro treatments.

Nitrogen utilization of potato genotypes and expression analysis of genes controlling nitrogen assimilation

INTRODUCTION

Significant differences in nitrogen use efficiency (NUE) were detected previously among potato cultivars. Exploration of the genetic background may facilitate the breeding of cultivars with highly effective nitrogen use.

METHODS

Expression of NUE genes was analyzed at three different N-supply levels in five potato genotypes. Correlations of NUE gene expressions and agronomical parameters with such indices as the nitrogen uptake efficiency, nitrogen utilization efficiency, NUE, and harvest indices were analyzed.

RESULTS

The correlations between expression level of the nitrate-reductase, nitrite-reductase, ammonium transporter, and asparagine synthase genes and different agronomically important parameters were detected.

DISCUSSION

Our results contribute to more rational, genotype-dependent nitrogen use in potato production and have relevance in breeding of new cultivars with better nitrogen utilization, as well as in production of seed potato.

The No-go decay system degrades plant mRNAs that contain a long A-stretch in the coding region

RNA quality control systems identify and degrade aberrant mRNAs, thereby preventing the accumulation of faulty proteins. Non-stop decay (NSD) and No-go decay (NGD) are closely related RNA quality control systems that act during translation. NSD degrades mRNAs lacking a stop codon, while NGD recognizes and decays mRNAs that contain translation elongation inhibitory structures. NGD has been intensively studied in yeast and animals but it has not been described in plants yet. In yeast, NGD is induced if the elongating ribosome is stalled by a strong inhibitory structure. Then, the mRNA is cleaved by an unknown nuclease and the cleavage fragments are degraded. Here we show that NGD also operates in plant. We tested several potential NGD cis-elements and found that in plants, unlike in yeast, only long A-stretches induce NGD. These long A-stretches trigger endonucleolytic cleavage, and then the 5' fragments are degraded in a Pelota-, HBS1- and SKI2- dependent manner, while XRN4 eliminates the 3' fragment. We also show that plant NGD operates gradually, the longer the A-stretch, the more efficient the cleavage. Our data suggest that mechanistically NGD is conserved in eukaryotes, although the NGD inducing cis-elements could be different. Moreover, we found that Arabidopsis AtPelota1 functions in both NGD and NSD, while AtPelota2 represses these quality control systems. The function of plant NGD will be discussed.

Expansion of Capsicum annuum fruit is linked to dynamic tissue-specific differential expression of miRNA and siRNA profiles

Small regulatory RNAs, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs) have emerged as important transcriptional and post-transcriptional regulators controlling a wide variety of physiological processes including fruit development. Data are, however, limited for their potential roles in developmental processes determining economically important traits of crops. The current study aimed to discover and characterize differentially expressed miRNAs and siRNAs in sweet pepper (Capsicum annuum) during fruit expansion. High-throughput sequencing was employed to determine the small regulatory RNA expression profiles in various fruit tissues, such as placenta, seed, and flesh at 28 and 40 days after anthesis. Comparative differential expression analyses of conserved, already described and our newly predicted pepper-specific miRNAs revealed that fruit expansion is accompanied by an increasing level of miRNA-mediated regulation of gene expression. Accordingly, ARGONAUTE1 protein, the primary executor of miRNA-mediated regulation, continuously accumulated to an extremely high level in the flesh. We also identified numerous pepper-specific, heterochromatin-associated 24-nt siRNAs (hetsiRNAs) which were extremely abundant in the seeds, as well as 21-nt and 24-nt phased siRNAs (phasiRNAs) that were expressed mainly in the placenta and the seeds. This work provides comprehensive tissue-specific miRNA and siRNA expression landscape for a developing pepper fruit. We identified several novel, abundantly expressing tissue- and pepper-specific small regulatory RNA species. Our data show that fruit expansion is associated with extensive changes in sRNA abundance, raising the possibility that manipulation of sRNA pathways may be employed to improve the quality and quantity of the pepper fruit.

The nonstop decay and the RNA silencing systems operate cooperatively in plants

Translation-dependent mRNA quality control systems protect the protein homeostasis of eukaryotic cells by eliminating aberrant transcripts and stimulating the decay of their protein products. Although these systems are intensively studied in animals, little is known about the translation-dependent quality control systems in plants. Here, we characterize the mechanism of nonstop decay (NSD) system in Nicotiana benthamiana model plant. We show that plant NSD efficiently degrades nonstop mRNAs, which can be generated by premature polyadenylation, and stop codon-less transcripts, which are produced by endonucleolytic cleavage. We demonstrate that in plants, like in animals, Pelota, Hbs1 and SKI2 proteins are required for NSD, supporting that NSD is an ancient and conserved eukaryotic quality control system. Relevantly, we found that NSD and RNA silencing systems cooperate in plants. Plant silencing predominantly represses target mRNAs through endonucleolytic cleavage in the coding region. Here we show that NSD is required for the elimination of 5' cleavage product of mi- or siRNA-guided silencing complex when the cleavage occurs in the coding region. We also show that NSD and nonsense-mediated decay (NMD) quality control systems operate independently in plants.

Comment on the publication of Amiryousefi et al. (2017)

This announcement describes corrections and comments to the paper entitled 'The plastid genome sequence of the invasive plant common Ragweed (Ambrosia artemisiifolia, Asteraceae)' by A Amiryousefi, J Hyvönen, P Poczai.

Illumina sequencing of the chloroplast genome of common ragweed (Ambrosia artemisiifolia L.)

Common ragweed (Ambrosia artemisiifolia L.) is the most widespread weed and the most dangerous pollen allergenic plant in large areas of the temperate zone. Since herbicides like PSI and PSII inhibitors have their target genes in the chloroplast genome, understanding the chloroplast genome may indirectly support the exploration of herbicide resistance and development of novel control methods. The aim of the present study was to sequence and reconstruct for the chloroplast genome of A. artemisiifolia and establish a molecular dataset. We used an Illumina MiSeq protocol to sequence the chloroplast genome of isolated intact organelles of ragweed plants grown in our experimental garden. The assembled chloroplast genome was found to be 152,215 bp (GC: 37.6%) in a quadripartite structure, where 80 protein coding genes, 30 tRNA and 4 rRNA genes were annotated in total. We also report the complete sequence of 114 genes encoded in A. artemisiifolia chloroplast genome supported by both MIRA and Velvet de novo assemblers and ordered to Helianthus annuus L. using the Geneious software.

Potato viruses and resistance genes in potato

Potato (Solanum tuberosum L.) is the fourth most important food crop in the world. It is the most economically valuable and well-known member of the plant family Solanaceae. Potato is the host of many pathogens, including fungi, bacteria, Phytoplasmas, viruses, viroids and nematodes, which cause reductions in the quantity and quality of yield. Apart from the late blight fungus [Phytophthora infestans (Mont.) de Bary] viruses are the most important pathogens, with over 40 viruses and virus-like pathogens infecting cultivated potatoes in the field, among which Potato virus Y (PVY), Potato leaf roll virus (PLRV), Potato virus X (PVX), Potato virus A (PVA), Potato virus S (PVS) and Potato virus M (PVM) are some of the most important viruses in the world. In this review, their characteristics and types of resistance to them will be discussed.

Re-visiting phylogenetic and taxonomic relationships in the genus Saga (Insecta: Orthoptera)

Twelve of the 13 bushcricket species of the Saga genus are bisexuals and diploids, except the parthenogenetic and tetraploid bush cricket, Saga pedo. Despite a continuous research effort stretching through the 1900s, the taxonomic relationships of the Saga species are still disputed. In this study, our primary aim was to reveal natural relationships of the European Saga species and three of their Asian relatives, with special attention to the problematic taxonomy of two subspecies: S. campbelli campbelli and S. c. gracilis. Following a phylogenetic analysis of eight species, a comprehensive study was carried out on the above three taxa by using acoustic and morphometric approaches in parallel. Our phylogenetic data showed that European Saga species evolved from a monophyletic lineage. The geographical transitional species S. cappadocica was positioned between European and Asian lineages supporting the idea that the European Saga lineage originated phylogeographically from the Asian clade. The above results showed better agreement with the morphological data than with earlier ones based either on karyology or acoustic information only. After reviewing our data, we concluded that Saga pedo has most likely evolved from S. c. gracilis and not from S. rammei or S. ephippigera, as proposed by earlier studies. S. c. gracilis shares the same ITS2 haplotype with S. pedo, indicating that the latter could have evolved from populations of the former, probably through whole genome duplication. Based on acoustic and morphometric differences, we propose to elevate the two subspecies, S. campbelli campbelli and S. c. gracilis, to species level status, as Saga gracilis Kis 1962, and Saga campbelli Uvarov 1921. The present work sets the stage for future genetic and experimental investigations of Saginae and highlights the need for additional comprehensive analysis involving more Asian Saga species.

Leaf-spot disease on European mistletoe (Viscum album) caused by Phaeobotryosphaeria visci: a potential candidate for biological control

Viscum album (European mistletoe), a perennial, evergreen, hemiparasitic shrub, infects a wide range of woody species. It adversely affects the height and diameter of growth and it is associated with increased mortality of its hosts. There is no effective control methods against it. We have found a specific hyperparasitic fungus, which can completely destroy European mistletoe by infecting its branches, leaves and berries. Both morphological and molecular identification, based on ribosomal internal transcribed spacer sequences (rDNA-ITS), established its identity as Phaeobotryosphaeria visci. Our analysis also revealed unexpected ITS variability, as compared to the previous studies, that needs to be considered in identifying of this pathogen. Because of its efficient pathogenicity this fungus might be a good candidate for biological control of mistletoe.

Genetic diversity and effect of temperature and pH on the growth of Macrophomina phaseolina isolates from sunflower fields in Hungary

The effects of temperature and pH on the growth of 45 Hungarian Macrophomina phaseolina isolates from different locations and hosts were compared on the basis of their genetic diversity. One Spanish and two Serbian isolates were also included in the experiment. The most favourable temperature regimes for the development of the isolates ranged between 25 and 35 °C. The optimal pH for the pathogen varied between 4.0 and 6.0, but growth was observed on potato dextrose agar even at pH values of 3.0, 7.0 and 8.0. RAPD analysis with 13 different primer pairs generated 148 unambiguous bands. RFLP analysis involving 8 different restriction endonucleases was performed on a 1550 bp fragment of the rDNA region containing internal transcribed spacers (ITS1, ITS2), the 5.8S rDNA and part of the 25S rDNA. The greatest genetic distance values were obtained for three isolates, two from Hungary and one from Spain, which had similar values, but were quite distinct from all the others. A strong positive correlation was observed between the genetic distances and the growth parameters measured at various temperatures, and between the geographical data and the growth data sets at different pH values, but the correlation was less strong in the latter case. While Hungarian M. phaseolina populations are thought to reproduce clonally, the present results indicate the coexistence of different haplotypes in this area, and besides the geographical dominance of a given haplotype it was found that a closer genetic relationship might exist between spatially distinct haplotypes.

Development of intron targeting (IT) markers for potato and cross-species amplification in Solanum nigrum (Solanaceae)

PREMISE OF THE STUDY

Intron Targeting (IT) primers were developed for potato using expressed sequence tags (EST) and NCBI database records to study genetic diversity. •

METHODS AND RESULTS

Twenty-nine polymorphic intron targeting (IT) markers were generated and characterized from 30 samples of potato and 22 samples of Solanum nigrum to detect polymorphism. The number of alleles (A) per locus ranged from 2 to 7 in the analyzed populations, and the observed heterozygosity (H(O)) and expected heterozygosity (H(E)) from 0 to 0.833 and 0.750, respectively. All of the primers also amplified in the related species S. nigrum. •

CONCLUSIONS

The developed markers will provide valuable tools for genetic diversity analysis, genetic mapping, and marker-assisted breeding of potato and related Solanum species.

Molecular characterization of atrazine resistance in common ragweed (Ambrosia artemisiifolia L.)

Common ragweed (Ambrosia artemisiifolia L.) is the most frequent weed in the Carpathian Basin and is spreading fast in other parts of Europe. In recent years, besides the wild type, a mutant genotype resistant to atrazine herbicides has evolved and is now widespread in many areas. The present study demonstrates that the atrazine resistance of ragweed is maternally inherited, and is caused by a point mutation in the psbA chloroplast gene. The promoter 5'-untranslated region and the open reading frame regions of the gene were analysed, and a homology search was performed. Both the atrazine-resistant and susceptible types of cpDNA were present in atrazine-resistant plants, while the mixed presence of both genotypes in the same plant, known as heteroplasmy, was not unequivocally detectable in susceptible plants.

Analysis of the applicability of molecular markers linked to the PVY extreme resistance gene Rysto, and the identification of new markers

In this study molecular markers linked to the Rysto gene, which originates from the wild potato species Solanum stoloniferum and confers extreme resistance against PVY, were identified and the applicability of recently published Rysto, markers was analyzed. Three RAPD markers covering a total distance of 8.60 cM were detected in this experiment. The closest of these markers was located 0.53 cM from the gene. From among the published markers only one had diagnostic value in the experimental plant material, and mapped 2.95 cM from the gene, on the side opposite the RAPD markers developed in the present study. All the markers analyzed were present in Solanum stoloniferum accessions, irrespective of their resistance, indicating that these sequences are linked to the locus and not exclusively to the dominant allele of the Rysto gene in the wild species. The inapplicability of several published markers indicates that the genetic background is decisive in this tetraploid and highly heterozygous species. This means that it may be necessary to develop markers from the breeding material itself, until the resistance gene is not cloned and cannot be used as a selection marker in marker-assisted selection.