The plant growth-promoting bacterial strain K. radicincitans DSM 16656 applied to A. thaliana reduced the number of phloem-feeding insects of both the specialist Brevicoryne brassicae and the ...generalist Myzus persicae. While weight gain of the generalist chewing insect Spodoptera exigua was reduced by 30% on A. thaliana plants treated with K. radicincitans, growth of the specialist caterpillar Pieris brassicae was not affected when compared with caterpillars from control plants. Since generalist and specialist chewing insects responded differentially to PGPB application, the implication of signaling pathways in PGPB mediated changes in plant defense was studied using two signaling pathway mutants impaired in their salicylic acid (npr1-1 mutant) or jasmonic acid (coi1-1 mutant) pathway. We found that the jasmonic acid pathway is relevant for upregulation of aliphatic glucosinolates and suppression of the chewing generalist S. exigua larval growth. Chewing from generalist P. brassicae increased glucosinolate content in A. thaliana leaves mediated via both signaling pathways. However, only in the npr1-1 mutant, which contains the highest aliphatic glucosinolate content, the P. brassicae induced further enrichment of glucosinolates, resulting in a reduction of larval growth. Effects of K. radicincitans on plant resistance could not be explained by changes in glucosinolate contents or composition. Our results demonstrate the distinct role played by K. radicincitans in suppressing insect performance in A. thaliana.
Abscisic acid (ABA) is an important phytohormone regulating various cellular processes in plants, including stomatal opening and seed germination. Although protein phosphorylation via ...mitogen-activated protein kinases (MAPKs) has been suggested to be important in ABA signaling, the corresponding phosphatases are largely unknown. Here, we show that a member of the Protein Phosphatase 2C (PP2C) family in Arabidopsis (Arabidopsis thaliana), PP2C5, is acting as a MAPK phosphatase. The PP2C5 protein colocalizes and directly interacts with stress-induced MPK3, MPK4, and MPK6, predominantly in the nucleus. Importantly, altered PP2C5 levels affect MAPK activation. Whereas Arabidopsis plants depleted of PP2C5 show an enhanced ABA-induced activation of MPK3 and MPK6, ectopic expression of PP2C5 in tobacco (Nicotiana benthamiana) resulted in the opposite effect, with the two MAPKs salicylic acid-induced protein kinase and wound-induced protein kinase not being activated any longer after ABA treatment. Moreover, depletion of PP2C5, whose gene expression itself is affected by ABA treatment, resulted in altered ABA responses. Loss-of-function mutation in PP2C5 or AP2C1, a close PP2C5 homolog, resulted in an increased stomatal aperture under normal growth conditions and a partial ABA-insensitive phenotype in seed germination that was most prominent in the pp2c5 ap2c1 double mutant line. In addition, the response of ABA-inducible genes such as ABI1, ABI2, RD29A, and Erd10 was reduced in the mutant plants. Thus, we suggest that PP2C5 acts as a MAPK phosphatase that positively regulates seed germination, stomatal closure, and ABA-inducible gene expression.
Aim The use of plant growth-promoting bacteria (PGPB) to reduce requirements for mineral nitrogen fertilization in sustainable agriculture is an important issue. We studied how reduced nitrogen ...fertilization affects the growth-promoting capacity oí Enterobacter radicincitans, the bacteria's root colonization behavior, and the regulation of nitrogen, phosphate and hormone marker genes in tomato (Solanum lycopersicum). Method Tomato seeds inoculated with 10 7 cfixmL⁻¹ E. radicincitans or 0.05 M NaCl, were grown under two distinct nitrogen fertilization regimes. Results When treated with E. radicincitans, plant root or shoot dry weight increased by 180 %, or 150 % in high nitrogen (HN) conditions, but increased only by 120 %, or 140 % in low nitrogen (LN) conditions. HN plants were colonized by a higher number of total bacteria, including E. radicincitans, than LN plants. We found that E. radicincitans-trQatQd plants expressed higher levels of a pathogen defense-related marker gene in LN conditions than in HN conditions. Transcription of the oxylipin biosynthesis marker genes was suppressed in E. radicincitans-treatod plants under both fertilization regimes. Conclusion Our findings indicate that drastic reduction in nitrogen fertilization results in modulating plant hormone signaling, thus inhibiting the optimal effect of E. radicincitans on tomato.
Conserving arable soils is a major challenge in agronomy. Using beneficial native microorganisms such as plant growth-promoting bacteria contributes to sustainability in agricultural systems and ...helps maintain stable yields and product quality. However, the growth-promoting effects of candidate strains observed in pot trials often disappear under field conditions. Therefore, we studied here the bacterial colonization of Kosakonia radicincitans, a known plant growth-promoting bacteria, and the effect of K. radicincitans on radish. We measured plant growth and glucosinolate profile when plants were grown under glasshouse and field conditions. K. radicincitans cells were applied onto seeds or plants when two leaves had emerged. Our results show an increase of up to 25 % of leaf and tuber weights of inoculated radish plants under glasshouse and field conditions, compared to non-inoculated plants. Glucosinolate contents remained unchanged, except when leaves were sprayed with K. radicincitans. We also found that K. radicincitans suppressed aromatic 2-phenylethyl glucosinolates in leaves. To sum up, we demonstrate for the first time the capability of K. radicincitans to persist and promote plant growth in a member of the Brassicaceae family under field conditions. Therefore, K. radicincitans is a promising candidate for further processing as a growth-promoting product in sustainable agriculture.
Plant growth-promoting bacteria (PGPB) affect plant cellular processes in various ways. The endophytic bacterial strain Enterobacter radicincitans DSM 16656 has been shown to improve plant growth and ...yield in various agricultural and vegetable crops. Besides its ability to fix atmospheric nitrogen, produce phytohormones, and solubilize phosphate compounds, the strain is highly competitive against native endophytic organisms and colonizes the endorhizosphere in high numbers. Here, we show that E. radicincitans inoculation of the noncrop plant Arabidopsis thaliana promotes plant growth. Furthermore, high performance liquid chromatography (HPLC) analysis revealed that bacterial inoculation slightly decreased amounts of aliphatic glucosinolates in plant leaves in a fast-growing stage but increased these compounds in an older phase where growth is mostly completed. This effect seems to correlate with developmental stage and depends on the nitrogen requirement. Additionally, nitrogen deficiency studies with seedlings grown on medium containing different nitrogen concentrations suggest that plant nitrogen demand can influence the intensity of plant growth enhancement by E. radicincitans. This endophyte seems not to activate stress-inducible mitogen-activated protein kinases (MAPKs). Analyzing transcription of the defense-related genes PR1, PR2, PR5, and PDF1.2 by quantitative real time polymerase chain reaction (qPCR) revealed that E. radicincitans DSM 16656 is able to induce priming via salicylic acid (SA) or jasmonate (JA)/ethylene (ET) signaling pathways to protect plants against potential pathogen attack.
Rocky Mountain spotted fever (RMSF) transmitted by the brown dog tick (Rhipicephalus sanguineus sensu lato) has emerged as a significant public health risk on American Indian reservations in eastern ...Arizona. During 2003-2012, more than 250 RMSF cases and 19 deaths were documented among Arizona's American Indian population. The high case fatality rate makes community-level interventions aimed at rapid and sustained reduction of ticks urgent. Beginning in 2012, a two year pilot integrated tick prevention campaign called the RMSF Rodeo was launched in a ∼ 600-home tribal community with high rates of RMSF. During year one, long-acting tick collars were placed on all dogs in the community, environmental acaricides were applied to yards monthly, and animal care practices such as spay and neuter and proper tethering procedures were encouraged. Tick levels, indicated by visible inspection of dogs, tick traps and homeowner reports were used to monitor tick presence and evaluate the efficacy of interventions throughout the project. By the end of year one, <1% of dogs in the RMSF Rodeo community had visible tick infestations five months after the project was started, compared to 64% of dogs in Non-Rodeo communities, and environmental tick levels were reduced below detectable levels. The second year of the project focused on use of the long-acting collar alone and achieved sustained tick control with fewer than 3% of dogs in the RMSF Rodeo community with visible tick infestations by the end of the second year. Homeowner reports of tick activity in the domestic and peridomestic setting showed similar decreases in tick activity compared to the non-project communities. Expansion of this successful project to other areas with Rhipicephalus-transmitted RMSF has the potential to reduce brown dog tick infestations and save human lives.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abscisic acid (ABA) is an important phytohormone regulating various cellular processes in plants, including stomatal opening and seed germination. Although protein phosphorylation via ...mitogen-activated protein kinases (MAPKs) has been suggested to be important in ABA signaling, the corresponding phosphatases are largely unknown. Here, we show that a member of the Protein Phosphatase 2C (PP2C) family in Arabidopsis (Arabidopsis thaliana), PP2C5, is acting as a MAPK phosphatase. The PP2C5 protein colocalizes and directly interacts with stress-induced MPK3, MPK4, and MPK6, predominantly in the nucleus. Importantly, altered PP2C5 levels affect MAPK activation. Whereas Arabidopsis plants depleted of PP2C5 show an enhanced ABA-induced activation of MPK3 and MPK6, ectopic expression of PP2C5 in tobacco (Nicotiana benthamiana) resulted in the opposite effect, with the two MAPKs salicylic acid-induced protein kinase and wound-induced protein kinase not being activated any longer after ABA treatment. Moreover, depletion of PP2C5, whose gene expression itself is affected by ABA treatment, resulted in altered ABA responses. Loss-of-function mutation in PP2C5 or AP2C1, a close PP2C5 homolog, resulted in an increased stomatal aperture under normal growth conditions and a partial ABA-insensitive phenotype in seed germination that was most prominent in the pp2c5 ap2c1 double mutant line. In addition, the response of ABA-inducible genes such as ABI1, ABI2, RD29A, and Erd10 was reduced in the mutant plants. Thus, we suggest that PP2C5 acts as a MAPK phosphatase that positively regulates seed germination, stomatal closure, and ABA-inducible gene expression.
Objectives To explore trends in suicide in young people to investigate the recent observation that after year on year rises in the 1970s, 1980s, and early 1990s, rates in young men are now ...declining.Design Time trend analysis.Setting England and Wales, 1968-2005.Population Men and women aged 15-34 years.Results Since the 1990s, rates of suicide in young men have declined steadily and by 2005 they were at their lowest level for almost 30 years. This decline is partly because of a reduction in poisoning with car exhaust gas as an increased number of cars have catalytic converters; but there have been declines in suicides from all common methods, including hanging, suggesting a more pervasive effect. Other risk factors for suicide, such as unemployment and divorce, have also decreased. Possible recent reductions in alcohol use among young men and increases in prescribing of antidepressants do not seem to be temporally related to the decline in suicide.Conclusions Suicide rates in young men have declined markedly in the past 10 years in England and Wales. Reductions in key risk factors for suicide, such as unemployment, might be contributing to lower rates.
Suicide rates vary by occupation but this relationship has not been frequently studied.
To identify the occupations with significantly high suicide rates in England and Wales in 2001-2005 and to ...compare these with rates from previous decades.
Mortality data from death registrations in England and Wales over the calendar years 2001-2005 were used to calculate proportional mortality ratios (PMRs) and standardised mortality ratios (SMRs) for both men and women aged 20-64 years by their occupation.
Among men, in 2001-2005, construction workers, and plant and machine operatives had the greatest number of suicides. The highest PMRs were for health professionals (PMR=164) and agricultural workers (PMR=133). Among women, administrative and secretarial workers had the greatest number of suicides yet the highest PMRs were found for health (PMR=232), and sport and fitness (PMR=244) occupations.
Excess mortality from suicide remains in some occupational groups. The apparent changes in suicide patterns merits further exploration, for example examining the prevalence of depression and suicidal ideation in medical practitioners, dentists, veterinarians, agricultural workers, librarians and construction workers.
Objective To assess the effect of the UK Committee on Safety of Medicines’ announcement in January 2005 of withdrawal of co-proxamol on analgesic prescribing and poisoning mortality.Design ...Interrupted time series analysis for 1998-2007.Setting England and Wales.Data sources Prescribing data from the prescription statistics department of the Information Centre for Health and Social Care (England) and the Prescribing Services Unit, Health Solutions Wales (Wales). Mortality data from the Office for National Statistics.Main outcome measures Prescriptions. Deaths from drug poisoning (suicides, open verdicts, accidental poisonings) involving single analgesics.Results A steep reduction in prescribing of co-proxamol occurred in the post-intervention period 2005-7, such that number of prescriptions fell by an average of 859 (95% confidence interval 653 to 1065) thousand per quarter, equating to an overall decrease of about 59%. Prescribing of some other analgesics (co-codamol, paracetamol, co-dydramol, and codeine) increased significantly during this time. These changes were associated with a major reduction in deaths involving co-proxamol compared with the expected number of deaths (an estimated 295 fewer suicides and 349 fewer deaths including accidental poisonings), but no statistical evidence for an increase in deaths involving either other analgesics or other drugs.Conclusions Major changes in prescribing after the announcement of the withdrawal of co-proxamol have had a marked beneficial effect on poisoning mortality involving this drug, with little evidence of substitution of suicide method related to increased prescribing of other analgesics.
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