Rs Strains Research Articles

Selection, inheritance, life-history traits, and flight capacity of Grapholita molesta (Lepidoptera: Tortricidae) resistant to lambda-cyhalothrin.

Grapholita molesta (Busck) (Lepidoptera: Tortricidae) is a globally significant fruit pest traditionally managed using chemical insecticides such as lambda-cyhalothrin. However, repeated applications have led to the development of resistance in field populations. The mechanisms and fitness costs associated with lambda-cyhalothrin resistance in G. molesta remain poorly understood. In this study, we established a lambda-cyhalothrin-resistant strain (RS) of G. molesta through continuous selection with lambda-cyhalothrin in the laboratory for 21 generations, resulting in a 249.6-fold increase in resistance. Bioassay data from the F1 progeny (F1RS and F1SR) of reciprocal crosses between RS and susceptible strain (SS) showed similar degrees of dominance (0.40 for F1RS and 0.32 for F1SR). Significant differences between observed and expected mortalities of backcross individuals suggested that resistance to lambda-cyhalothrin is polygenic. Compared to the SS strain, the RS strain exhibited significantly prolonged periods of larval, prepupal, and pupal stages, as well as a significant decrease in larval weight. In addition, the RS strain showed significant reductions in fecundity, cumulative flight distance, maximum flight distance, cumulative flight time, maximum flight time, and average flight speed. These results suggest that resistance to lambda-cyhalothrin in G. molesta is autosomal, incompletely dominant, and polygenic. Life-history traits such as fecundity and flight capacity were significantly reduced in RS strains compared with the SS strain. These findings provide valuable insights for mitigating lambda-cyhalothrin resistance development and promoting sustainable control of G. molesta in the field.

First report of 'Candidatus Phytoplasma rubi' associated with Rubus stunt disease of raspberry and blackberry in the Czech Republic.

Raspberries (Rubus idaeus L.), occurring in the temperate zone of the northern hemisphere and blackberries (R. fruticosus L.), cultivated and growing all over the world, are plant species of the family Rosaceae. These species are susceptible to phytoplasma infections, which cause Rubus stunt disease. It spreads uncontrolled by vegetative propagation of plants (Linck and Reineke 2019a) and by phloem-sucking insect vectors, especially Macropsis fuscula (Hemiptera: Cicadellidae) (de Fluiter and van der Meer, 1953; Linck and Reineke 2019b). During a survey in commercial field in June 2021, over 200 raspberry bushes cv Enrosadira exhibiting typical symptoms of Rubus stunt were observed in Central Bohemia. Symptoms included dieback, leaf yellowing/reddening, stunted growth, severe phyllody and fruit malformations. Most diseased plants were growing in the edge rows of the field (about 80%). No symptomatic plants were observed in the middle of the field. Similar symptoms were observed in private gardens in South Bohemia on raspberry cv Rutrago and blackberry (unknown cultivar) in June 2018 and August 2022, respectively. DNA was extracted using the DNeasy Plant Mini Kit (Qiagen GmbH, Hilden, Germany) from flower stems and parts affected by phyllody of seven symptomatic plants as well as flower stems, leaf midribs, and petioles of five asymptomatic field plants. The DNA extracts were analyzed by a nested polymerase chain reaction assay using universal phytoplasma P1A/P7A primers followed by R16F2m/R1m and the group-specific R16(V)F1/R1 primers (Bertaccini et al. 2019). All samples from the symptomatic plants yielded an amplicon of expected size, while no product was amplified in asymptomatic plants. The P1A/P7A amplicons from three selected plants (two raspberries and one blackberry, each from different location) were cloned and bi-directionally Sanger sequenced (GenBank Accession Nos.OQ520100-2). The sequences spanned nearly full-length of 16S rRNA gene, 16S-23S rRNA intergenic spacer, tRNA-Ile gene, and a partial 23S rRNA gene. BLASTn search revealed the highest sequence identity (99.8-99.9%, query coverage 100%) to 'Candidatus Phytoplasma rubi' strain RS (GenBank Accession No. CP114006). To further characterize the 'Ca. P. rubi' strains, all these three samples were subjected to multigene sequence analysis. Sequences from a major portion of the tuf, rplV-rpsC, rpsH-rplR, uvrB-degV, and rplO-SecY-map genes (Acc. Nos. OQ506112-26) were obtained as described previously (Fránová et al. 2016). Comparison to GenBank sequences confirmed their highest identity (99.6-100%, query coverage 100%) with 'Ca. P. rubi' RS strain, regardless of their geographic location and host (raspberry or blackberry). Recently, Bertaccini et al. (2022) suggested the 98,65 % 'Ca. Phytoplasma' strain identity threshold within 16Sr RNA sequences. In this survey, all three strains sequenced shared ≥99.73% sequence identity of the analysed 16S rRNA gene sequences and the high identity in the other genes with the reference 'Ca. P. rubi' RS strain. To our knowledge, this is the first report of Rubus stunt disease in the Czech Republic as well as the first molecular identification and characterization of 'Ca. P. rubi' from raspberry and blackberry in our country. As Rubus stunt disease is of great economic importance (Linck and Reineke 2019a), the pathogen detection and prompt removal of the diseased shrubs are essential to mitigating the spread and impact of the disease.

Sublethal and transgenerational effects of pyridaben exposure on the fitness and gene expression of Panonychus citri.

Panonychus citri is a globally dominant citrus plant pest mite. Pesticide-induced population resurgence is a concern for mite control. Exposure to sublethal concentrations of pesticides has stimulated reproduction and outbreak risks in many pests. Pyridaben, a mitochondrial electron transport inhibitor, has been frequently used worldwide in mite control. In the study, sublethal and transgenerational effects of pyridaben exposure on Pyr_Rs (resistant) and Pyr_Control (susceptible) strains were systematically investigated in both exposed parental generation (F0 ) and unexposed offspring generations (F1 and F2 ) by evaluating life-table and physiological parameters. After exposure to pyridaben, the fecundity of both strains was significantly reduced in F0 generation while significantly induced in F1 generation. Interestingly, these effects also stimulated the fecundity of the F2 generation in Pyr_Control strain while no significant effects occurred for Pyr_Rs strain. The intrinsic rate of increase (r) and finite rate of increase (λ) were significantly decreased only in F1 generation of Pyr_Control strain after exposure treatment. Meanwhile, the population projection indicated a smaller population size in F1 generation of Pyr_Control strain while a population increase for Pyr_Rs strain after sublethal treatment. Subsequent detoxification enzyme assays indicated that only P450 activities in F0 generation were significantly activated by LC30 exposure to pyridaben in both strains. Significant downregulation of reproduction-related (Pc_Vg) genes was observed in the F0 generations of both strains. Significant upregulation of P450 (CYP4CL2) and PcVg of the F1 generation in both strains suggested the presence of delayed hormesis effects on the reproduction and developed tolerance to pyridaben, although the effects didn't last over a longer period (F2 generation). These results provide evidence for transgenerational hormesis effects of low concentrations of pyridaben exposure that may lead to population increase and resurgence risks of resistant-mites in natural settings by stimulating reproduction. This article is protected by copyright. All rights reserved.

First Report of Bacterial Wilt Disease Caused by Ralstonia solanacearum on Southern Highbush Blueberries (Vaccinium corymbosum interspecific hybrids) in Georgia U.S.A.

Members of the Ralstonia solanacearum (Rs) species complex have recently been reported to cause bacterial wilt on southern highbush (SHB) blueberries in Florida (Norman et al. 2018), a disease first reported on blueberry (northern highbush; Vaccinium corymbosum) in New Jersey (Patel et al. 2013). SHB blueberries are widely grown in the southern United States, and SHB cultivars represent the majority of the blueberry acreage in Georgia - the U.S. state with the largest blueberry acreage (NASS 2022). In Fall 2020, three-year old SHB plants (cv. 'Indigocrisp') showing leaf bronzing, wilting, and dieback were collected from two field sites in Clinch County, GA. At these locations, numerous plants were rapidly dying, with symptoms appearing to have spread down rows. Plant material tested positive using the ImmunoStrip® for Rs (Agdia, Inc., Elkhart, IN). From one location, the remaining sample was submitted to USDA-APHIS Select Agent Services who determined that Rs was present but a select agent (Rs Race 3, Biovar 2) was not. Following this, six adjacent, symptomatic SHB plants were collected from the same field location. These plants tested positive using the ImmunoStrip® for Rs, and red-pigmented mucoid colonies typical of Rs formed within 48 h at 28°C on triphenyltetrazolium chloroide (TZC) isolation medium (Kelman 1954). DNA was extracted from pure Rs cultures using the cetyltrimethylammonium bromide (CTAB) method (Doyle and Doyle 1987) and tested using polymerase chain reaction (PCR). Primers pairs AMB013/AMB014 (Fegan and Prior 2005) and ENDO-F/ENDO-R (Ji et al. 2007) were used to amplify 558 nt and 843 nt portions of the 16S rRNA region and Rs endoglucanase gene, respectively. Resulting amplicons were purified using an E.Z.N.A.® Cycle Pure Kit (Omega Bio-Tek, Norcross, GA), Sanger sequenced in both directions (Eurofins Genomics, Louisville, KY), and compared to publicly available Rs sequences in Genbank. The 16 rRNA sequence from all obtained isolates (accession ON938207) had 100% identity to Rs strain CFBP2957 (FP885897), while the endoglucase sequence (ON938206) had 100% identity to phylotype IIa, sequevar 5 Rs strain CIP-426 (MF461810) and phylotype IIa, sequevar 39 Rs strain 19-058 (MT314067), among others. To fulfill Koch's postulates, an isolate ('Ral21-1') was grown on TZC medium for 48 h at 28°C and suspended in 8.5 g/L NaCl at 1 x 108 CFU/ml. Five young, tissue cultured SHB plants (cv. 'Kestrel') in 25 cm pots were drenched with 50 ml of Rs suspension. For six weeks, plants were maintained in the greenhouse at 21-32°C. Typical bacterial wilt symptoms (leaf bronzing/scorching) developed in all inoculated plants, and infections were confirmed using Immunostrip®. Rs was reisolated and confirmed via PCR and sequencing as previously described. While Ralstonia has been known to cause disease on numerous crops in Georgia, this represents a first report of bacterial wilt in Georgia blueberries. Relative to rabbiteye blueberries (V. virgatum), recent reports suggest that SHB are much more susceptible to bacterial wilt (Conner et al. 2022). Accordingly, given the transition from rabbiteye to SHB within Georgia's blueberry production region over the past two decades and the ability of Rs to spread easily in water, soil, or via infected plant material, the presence of this disease within the state represents a significant threat to blueberry production. Additional characterization of Ralstonia isolates from Georgia may help assess the risk of future outbreaks.

The sublethal and transgenerational effects of pyridaben on fitness and induced tolerance in Panonychus citri

Panonychus citri is a dominant citrus pest mite in the world. Pesticide-induced population resurgence is a concern for environmental and resistance risk assessment in mite control. To evaluate the effective mite management strategies, the sublethal and transgenerational effects of pyridaben on P. citri were assessed using life-table parameters. Two segregated pyridaben-resistant and susceptible strains (previously obtained from the crossing between laboratory susceptible strain and pyridaben-resistant population) were used in our study. After exposure to LC30 pyridaben, the fecundity of Pyr_Control and Pyr_Rs strains were both significantly reduced in the parental generation (F0). Life-table results showed that LC30 pyridaben significantly induced the fecundity of both strains in F1 generation (egg stage was prolonged as well). Interestingly, this effect also stimulated the fecundity of F2 generation in Pyr_Control strain. But no significant effects were observed in Pyr_Rs strain. While detoxification enzyme assays indicated that only the activity of P450s was significantly activated by LC30 pyridaben in Pyr_Control and Pyr_Rs strains (1.242- fold and 1.355-fold increase, respectively). The expressions of P450 gene (CYP4CL2) and reproduction-related gene (Pc_Vg) were determined and the results showed that the expression of Pc_Vg of pyridaben treated mites in F0 generation was significantly reduced in both strains. In Pyr_Control and Pyr_Rs strains, the significant upregulation CYP4CL2 (2.029-fold and 2.516-fold increase, respectively) and PcVg (1.771-fold and 2.924-fold increase, respectively) of F1 generation suggested there were delayed hormesis effects on reproduction and developed tolerance to pyridaben. No significant difference was found between LC30 treatments and controls in F2 generation of both strains. These results provided evidence that transgenerational hormesis effects of low concentration of pyridaben might lead to mite population outbreak and resistance risk in the field through stimulating the reproduction and developing tolerance to pyridaben. Furthermore, LC30 pyridaben could affect the offspring populations of susceptible strain in the longer-term as compared to resistant strain.

Resistance of Panonychus citri (McGregor) (Acari: Tetranychidae) to pyridaben in China: monitoring and fitness costs.

Panonychus citri is a major citrus pest worldwide. The short life cycle and high reproductive potential of P. citri, combined with heavy acaricide use, have led to high levels of resistance to acaricides, posing a threat to global resistance management programs. Here, resistance monitoring was established to determine the pyridaben resistance status of ten P. citri populations in China from 2014 to 2021 using a leaf-dipping assay. Four characterized strains-the susceptible strain (Lab_S), the resistant strain (Pyr_R), as well as the segregated resistant strain (Pyr_Rs) and the segregated susceptible strain (Pyr_Control) derived from the crossing of the Lab_S and Pyr_R strains, were used to evaluate the life-history characteristics using age-stage, two-sex life tables. Most P. citri populations developed high resistance to pyridaben. Resistance levels exceeded 1000-fold in Yuxi, Anyue, Nanning, and Ganzhou populations compared with the Lab_S strain. Compared with Pyr_Control, two key fitness cost criteria, developmental period and fecundity, showed significant differences in Pyr_Rs under consistent conditions. The intrinsic rate of increase, net reproductive rate and gross reproductive rate were lower in the resistant strain compared with the Pyr_Control strain. The Pyr_Rs strain had a lower relative fitness of 0.934 compared with the Pyr_Control. Moreover, the life-history traits and population parameters of the Pyr_R strain also showed significant differences compared with the Lab_S strain. The resistance levels to pyridaben varied greatly among the different P. citri populations and showed regional differences. Substantial fitness costs are associated with pyridaben resistance. This study provides potential implications for developing strategies for resistance management in P. citri. © 2022 Society of Chemical Industry.

Resistance to Bacterial Wilt in Solanum commersonii Dun.

The levels of resistance to bacterial wilt (BW) of potatoes caused by Ralstonia solanacearum (Rs) are limited. Solanum commersonii (cmm) is a wild tuber-bearing potato highlighted for its resistance to BW. This research aimed to (i) characterize cmm genotypes for resistance to Rs (race 3, biovar 2) using a soil inoculation method, (ii) determine to what extent resistance in cmm is transmissible through sexual reproduction to a susceptible genetic background, and (iii) determine the relationships between a set of Rs strains (race 3, biovar 2) and cmm genotypes in the expression of resistance. The screening was performed under controlled conditions of temperature and light. Accessions collected from different regions of Uruguay showed diversity for resistance to BW: some genotypes were asymptomatic in the response, while for others the symptoms were similar to the susceptible control. Two cmm genotypes with contrasting responses to BW were crossed, and an offspring of 121 genotypes was obtained. The distribution of BW resistance levels in the progeny suggested a polygenetic control for BW resistance; though this conclusion is preliminary regarding that one of the cmm parents was triploid. A factorial experiment using five R. solanacearum strains isolated in Uruguay and five cmm clones showed differences in the virulence between strains. There was no interaction between plant genotype and bacterial isolate, and therefore, under the conditions of this research, BW resistance in cmm was not dependent on the isolate of the pathogen.

Interrelation between Stress Management and Secretion Systems of Ralstonia solanacearum: An In Silico Assessment.

Ralstonia solanacearum (Rs), the causative agent of devastating wilt disease in several major and minor economic crops, is considered one of the most destructive bacterial plant pathogens. However, the mechanism(s) by which Rs counteracts host-associated environmental stress is still not clearly elucidated. To investigate possible stress management mechanisms, orthologs of stress-responsive genes in the Rs genome were searched using a reference set of known genes. The genome BLAST approach was used to find the distributions of these orthologs within different Rs strains. BLAST results were first confirmed from the KEGG Genome database and then reconfirmed at the protein level from the UniProt database. The distribution pattern of these stress-responsive factors was explored through multivariate analysis and STRING analysis. STRING analysis of stress-responsive genes in connection with different secretion systems of Rs was also performed. Initially, a total of 28 stress-responsive genes of Rs were confirmed in this study. STRING analysis revealed an additional 7 stress-responsive factors of Rs, leading to the discovery of a total of 35 stress-responsive genes. The segregation pattern of these 35 genes across 110 Rs genomes was found to be almost homogeneous. Increasing interactions of Rs stress factors were observed in six distinct clusters, suggesting six different types of stress responses: membrane stress response (MSR), osmotic stress response (OSR), oxidative stress response (OxSR), nitrosative stress response (NxSR), and DNA damage stress response (DdSR). Moreover, a strong network of these stress responses was observed with type 3 secretion system (T3SS), general secretory proteins (GSPs), and different types of pili (T4P, Tad, and Tat). To the best of our knowledge, this is the first report on overall stress response management by Rs and the potential connection with secretion systems.

Screening for Ralstonia solanacearum Resistance in Solanum commersonii

Worldwide, potato (Solanum tuberosum L) is rated as one of the most important food crops after wheat, rice and maize. Bacterial wilt, caused by Ralstonia solanacearum (Rs), is one of the most economically important diseases of potato. The purpose of this study was to identify diploid germplasm with resistance to bacterial wilt. The wilting degree was assessed by analyzing the wilt percentage of six Solanum commersonii clones which were artificially inoculated with Rs in a growth chamber. Two Rs strains (CMR15 and UW551) were used to inoculate the clones evaluate resistance. MSEE912–08, a selfed progeny from PI320266 was identified as the most resistant of the clones in this study exhibiting the lowest RAUDPC for wilting and a Wilting Degree rating of 0.4 (less than 25% wilted leaves) 20 days post inoculation when inoculated with the UW551 Rs strain, and 1.3 with the CMR15 strain. The resistance observed was characterized by reduction in wilting over time, rather than lack of disease. The most resistant clone from this study was self-pollinated to create a mapping population to identify single nucleotide polymorphic (SNP) markers associated with Rs resistance.

Genetic diversity of Ralstonia solanacearum strains causing bacterial wilt of solanaceous crops in Myanmar

In 2013 and 2014, an extensive survey of bacterial wilt in Myanmar was performed, and 70 strains of Ralstonia solanacearum (Rs) were collected from wilting plants of tomato, potato, chili and eggplant. Myanmar Rs strains were characterized by traditional and molecular methods. Polymerase chain reaction (PCR) test using Rs-specific primer set amplified one specific band (281-bp) from template DNA of all strains. Pathogenicity tests on the four solanaceous plants differentiated the strains into six pathogenic groups. Biovar determination tests showed that biovar 3 strains predominated (63%) among all Rs strains. Biovar 4 strains (7%) were obtained from both tomato and chili strains, whereas biovar 2 (30%) strains were isolated only from potato. Multiplex-PCR analysis indicated that tomato, eggplant and chili strains belonged to phylotype I, whereas potato strains comprised phylotype I and phylotype II. Strains in phylotype I, which was suggested to have originated from Asia, were the most prevalent in all surveyed areas. Phylogenetic analysis based on the endoglucanase (egl) gene sequences revealed that Myanmar strains partitioned into two major clusters that corresponded to phylotype I and II. Strains in phylotype I were further divided into seven subclusters, each corresponding to a distinct sequevar (15, 17, 46, 47, 48, unknown 1 or unknown 2). All strains in phylotype II belonged to sequevar 1. This is the first comprehensive report of the presence of diverse Rs strains in Myanmar.

Влияние наноструктурированных систем «хитозан-наночастицы золота», «хитозан-пчелиный яд-наночастицы золота» на структуру и массу опухоли, перекисное окисление липидов и функциональное состояние крыс с опухолью РС-1

The purpose of this research is the study of anti-tumor efficacy of nanostructured systems, «chitosan-gold nanoparticles», «chitosan-bee venom-gold nanoparticles» аnalysis morphological changes and growth of tumor tissue, as well as the study of properties of adaptogenic and prooxidant properties of nanosystems in laboratory animals with transplanted tumors RS strain -1. As a result of studying of histological sections of tumor tissue, determining tumor mass, the activity of free radical oxidation in plasma and tumor tissue, the values of leukocyte formula and leukocyte coefficient shows antitumor, prooxidant and adaptogenic effectiveness of nanostructured systems.

Shape memory-based tunable resistivity of polymer composites

A conductive composite in bi-layer structure was fabricated by embedding hybrid nanofillers, namely carbon nanotubes (CNTs) and silver nanoparticles (AgNPs), into a shape memory polyurethane (SMPU). The CNT/AgNP-SMPU composites exhibited a novel tunable conductivity which could be facially tailored in wide range via the compositions or a specifically designed thermo-mechanical shape memory programming. The morphologies of the conductive fillers and the composites were investigated by scanning electron microscope (SEM). The mechanical and thermal measurements were performed by tensile tests and differential scanning calorimetry (DSC). By virtue of a specifically explored shape memory programming, the composites were stretched and fixed into different temporary states. The electrical resistivity (Rs) varied accordingly, which was able to be stabilized along with the shape fixing. Theoretical prediction based upon the tunneling model was performed. The Rs–strain curves of the composites with different compositions were well fitted. Furthermore, the relative resistivity and the Gauge factor along with the elongation were calculated. The influence of the compositions on the strain-dependent Rs was disclosed. The findings provided a new avenue to tailor the conductivity of the polymeric nano-composites by combining the composition method and a thermo-mechanical programming, which may greatly benefit the application of intelligent polymers in flexible electronics and sensors fields.

Cross-Resistance between Cry1 Proteins in Fall Armyworm (Spodoptera frugiperda) May Affect the Durability of Current Pyramided Bt Maize Hybrids in Brazil.

Genetically modified plants expressing insecticidal proteins from Bacillus thuringiensis (Bt) offer valuable options for managing insect pests with considerable environmental and economic benefits. Despite the benefits provided by Bt crops, the continuous expression of these insecticidal proteins imposes strong selection for resistance in target pest populations. Bt maize (Zea mays) hybrids have been successful in controlling fall armyworm (Spodoptera frugiperda), the main maize pest in Brazil since 2008; however, field-evolved resistance to the protein Cry1F has recently been reported. Therefore it is important to assess the possibility of cross-resistance between Cry1F and other Cry proteins expressed in Bt maize hybrids. In this study, an F2 screen followed by subsequent selection on MON 89034 maize was used to select an S. frugiperda strain (RR) able to survive on the Bt maize event MON 89034, which expresses the Cry1A.105 and Cry2Ab2 proteins. Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found. The RR strain showed high levels of resistance to Cry1F, which apparently also conferred high levels of cross resistance to Cry1A.105 and Cry1Ab, but had only low-level (10-fold) resistance to Cry2Ab2. Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively. Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil. Nevertheless, the occurrence of Cry1F resistance in S. frugiperda across Brazil, and the cross-resistance to Cry1Ab and Cry1A.105, indicates that current Cry1-based maize hybrids face a challenge in managing S. frugiperda in Brazil and highlights the importance of effective insect resistance management for these technologies.

A quantitative hybridization approach using 17 DNA markers for identification and clustering analysis of Ralstonia solanacearum

Ralstonia solanacearum (Rs) is a quarantine phytopathogenic bacterium accountable for heavy economic losses worldwide. Monitoring and eradication programmes required for this pathogen are dependent on the availability of time‐ and cost‐efficient detection and typing methods. However, members of the Rs species complex are characterized by a high phenotypic and genetic diversity, which requires improved diagnostics methods. The currently available full genome sequences of several Rs strains allow for the selection of novel specific DNA markers using comparative genomics tools. In this work, 17 novel markers were selected based on Rs‐specific protein domains and thoroughly validated for specificity and stability, both in silico and using ‘wet lab’ assays. Polymerase chain reaction‐ and hybridization‐based validation assays revealed that the DNA regions selected as markers were unevenly distributed amongst the tested strains, with nine markers present throughout the species complex. The distribution of the remaining eight markers was highly variable between the different analysed strains and enabled the attainment of strain‐specific dot blot hybridization patterns, particularly informative for typing. The average probability value of each strain being positive for each of the 17 markers was calculated by an algorithm and used to obtain a dendrogram representing hierarchical clustering analysis of Rs, according to the similarity of their hybridization patterns. This method should prove to be a robust and straightforward procedure for genotyping members of the Rs species complex. Furthermore, this quantitative hybridization approach will allow the construction of informative databases to determine new Rs genotypes and infer epidemiological patterns.

A duplex PCR assay for the detection of Ralstonia solanacearum phylotype II strains in Musa spp.

Banana wilt outbreaks that are attributable to Moko disease-causing strains of the pathogen Ralstonia solanacearum (Rs) remain a social and economic burden for both multinational corporations and subsistence farmers. All known Moko strains belong to the phylotype II lineage, which has been previously recognized for its broad genetic basis. Moko strains are paraphyletic and are distributed among seven related but distinct phylogenetic clusters (sequevars) that are potentially major threats to Musaceae, Solanaceae, and ornamental crops in many countries. Although clustered within the Moko IIB-4 sequevar, strains of the epidemiologically variant IIB-4NPB do not cause wilt on Cavendish or plantain bananas; instead, they establish a latent infection in the vascular tissues of plantains and demonstrate an expanded host range and high aggressiveness toward Solanaceae and Cucurbitaceae. Although most molecular diagnostic methods focus on strains that wilt Solanaceae (particularly potato), no relevant protocol has been described that universally detects strains of the Musaceae-infecting Rs phylotype II. Thus, a duplex PCR assay targeting Moko and IIB-4NPB variant strains was developed, and its performance was assessed using an extensive collection of 111 strains representing the known diversity of Rs Moko-related strains and IIB-4NPB variant strains along with certain related strains and families. The proposed diagnostic protocol demonstrated both high accuracy (inclusivity and exclusivity) and high repeatability, detected targets on either pure culture or spiked plant extracts. Although they did not belong to the Moko clusters described at the time of the study, recently discovered banana-infecting strains from Brazil were also detected. According to our comprehensive evaluation, this duplex PCR assay appears suitable for both research and diagnostic laboratories and provides reliable detection of phylotype II Rs strains that infect Musaceae.

Dillapiol: a pyrethrum synergist for control of the Colorado potato beetle.

Dillapiol, the main constituent in dill Anethum sowa Roxb. ex Fleming (Apiaceae) oil and wild pepper, Piper aduncum L. (Piperaceae), is an effective cytochrome P450 inhibitor similar to piperonylbutoxide (PBO). Laboratory and field trials with pyrethrum Chrysanthemum cinerariifolium (Trevir.) vis. extracts combined with dillapiol (1:5 and 1:16 ratio) were effective against both insecticide-susceptible and -resistant Colorado potato beetle Leptinotarsa decemlineata (Say). In the laboratory, pyrethrum efficacy was increased 2.2-fold with the SS strain and 9.1-fold with the RS strains by using pyrethrum + dillapiol. Two field trials with the pyrethrum + dillapiol formulation demonstrated efficacy > or = 10 times than that of pyrethrum alone. The residual activity (half-life) of the combination exposed to direct sunlight was 3 h but it increased to 10.7 h by adding 2% of the sunscreen octylmethoxycinnamate.

Pathogenic characters of Japanese potato strains of Ralstonia solanacearum

Ralstonia solanacearum (Rs) strains in phylotypes I and IV isolated from potato in Japan were investigated for pathogenicity on potato, tomato, eggplant, Solanum integrifolium, tobacco, groundnut, and pumpkin. The strains were divided into 17 types based on differences in their pathogenicity on the tested plants. Particularly, the pathogenicity of most phylotype I strains on eggplant was distinctly different from that of the phylotype IV strains. When nine potato varieties (included two breeding lines) were inoculated with several Rs strains, phylotype IV strains were highly virulent on the breeding lines that are regarded as resistant to phylotype I strains.

Quality of meat from two 1970s and Ross 308 broiler strains fed drug-free low- and recommended-protein diets

SUMMARY A study was conducted to compare the quality of meat from a modern broiler strain (Ross 308; RS) with that of two 1970s strains fed drug-free low-protein (LP) and recommendedprotein (RP) diets from 1 to 30 d of age. The RP and LP starter and grower diets were fed from 1 to 16 d and from 16 to 30 d of age, respectively. The LP grower diet was fed to all birds from d 31 to 63. Breast and thigh meats were less (P < 0.05) fibrous for the RS strain than for the 1970s strains. The breast meat of the RS strain was also juicier (P < 0.05) than that of the 1970s strains when the LP diet was fed. Thigh meat from 7-wk-old birds was less fibrous (P < 0.05) than that from 9-wk-old birds. The LP diet improved (P < 0.05) the tenderness of breast and thigh meats, but the improvement in breast meat tenderness was significant (P < 0.05) only for 7-wk-old birds. Breast and thigh meats from RS birds had higher (P < 0.05) pH and water-holding capacity than those from the 1970s strains. Breast meat from the RS birds had a higher (P < 0.05) percentage of fat (1.23 vs. 0.55 and 0.73%) and a lower (P < 0.05) percentage of protein (24.17 vs. 24.90 and 24.78%) than the 1970s strains. Meat from the RS strain had better sensory attributes and quality characteristics than meat from the two 1970s strains. Meat from the 1970s strains had a higher protein content and lower fat content than meat from the RS birds. The LP diet can improve meat sensory attributes if the birds are slaughtered at 7 wk of age, but not at 9 wk of age.

In silico genomic subtraction guides development of highly accurate, DNA-based diagnostics for Ralstonia solanacearum race 3 biovar 2 and blood disease bacterium

New rapid diagnostic methods are urgently needed to discriminate the quarantine pathogen Ralstonia solanacearum (Rs) race 3 biovar 2 (R3B2) from other populations of Rs that lack the adaptation to cause bacterial wilt disease in temperate regions. We used an in silico bioinformatic approach to identify several genome sequences potentially specific to R3B2 strains. Primer sets were designed to PCR-amplify sequences in these regions, and four sets were ultimately shown to be >99% accurate for detection of R3B2 strains. On the basis of these results, several primers were designed to enable development of a loop-mediated isothermal amplification assay that was rapid, technologically simple, and essentially 100% accurate for identification of R3B2 when applied to a comprehensive collection of geographically diverse Rs strains. We fortuitously found that a sequence in one of the “R3B2-specific” regions has ~90% identity to a sequence present in strains of the blood disease bacterium (BDB), a member of the Rs species complex that infects banana. Alignments of these sequences allowed design of a second PCR primer set that proved 100% accurate for identification of BDB strains when tested on the 22 BDB strains available to us. These results demonstrate the power of in silico genomic subtraction for rapid identification of population-specific DNA sequences and for the development of simple, reliable detection methods for Rs subpopulations.

Right Ventricular Systolic Pressures in Patients with Normal Left Ventricular Systolic Function—A Study of 51,429 Australian Echocardiograms

Objective: To evaluate the longitudinal function of left side (Ls) and right side ventricular septum (Rs) during treatment of patients with pulmonary hypertension (PAH). Background: Leftwards shift and flattening of the interventricular septum are recognised consequences of RV pressure overload. Rs and Ls respond differently to various conditions, however little is known about longitudinal strain changes in patients with PAH. Method: Twenty controls and 21 chronic PAH patients were studied.A 3.5MHz transducer (GE,Vivid 7)was used for imaging (frame rate 50–80). Rs and Ls segmental peak systolic longitudinal strains were obtained in the apical four chamber view at baseline and at sixmonthly intervals over 24 months follow up during treatment with either Bosentan or Sildenafil. Results: In control subjects, Rs and Ls longitudinal Figure 1.