561 research outputs found

    Factors affecting the spread of "Bois Noir" disease in north Italy vineyards

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    To define control strategies for “Bois Noir” disease (BN) it is necessary to know factors favouring its spreading by the vector Hyalesthes obsoletus Signoret. During 2003-2006 a research was carried out in 18 vineyards of a grape-growing area of North Italy to assess the influence of insecticides, applied on grapevine canopies, and environment surrounding the vineyards on disease spreading. The vector population density was higher outside than in the centre of the vineyards. Insecticides applied to grapevine canopies did not significantly influence the vector population level in the centre of the vineyards. The majority of vineyards showed randomized distribution of symptomatic grapevines. Seven vineyards had an aggregate distribution due to an edge effect from a border side with nettle. The incidence of border sides not contiguous to other grapevine rows on vineyard surface was positively related to higher levels of BN. The incidence of border sides with nettle on vineyard surface was positively correlated to disease incidence in the vineyards with aggregate distribution of symptomatic grapevines. All the data support the importance of surrounding vegetation as source of inoculum of BN phytoplasma. Molecular analyses on ribosomal and tuf genes show that 16 out of the 18 vineyards were affected only by BN: in 13 only tuf-type I was identified, in 2 only tuf-type II, in 1 both tuf-types, and in 2 it was not possible to identify the tuf-type of phytoplasmas detected. In the weeds tested only tuftype II phytoplasmas were identified while H. obsoletus was carrying both phytoplasma tuf-types.

    Induction of resistance and enhancing agronomic performance in grapevines under greenhouse and in open fields by applications of plasma activated water

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    The exposure of water to a cold atmospheric pressure plasma (CAP) enables the production of plasma activated water (PAW), having high content of reactive species, whose applications were tested on grapevine plants, both in greenhouse and in vineyard conditions. Two different CAPs were used for PAW production, evaluating their effectiveness as a possible mean to control plant diseases. Grapevines infected with yellows associated with the presence of phytoplasmas were treated evaluating qualitative and quantitative yield parameters, phytoplasma presence, and gene expression. The results show the capability of PAW to enhance plant defence mechanisms and, as demonstrated in the field trials, confirmed its ability to improve the health status of the treated plants. Quantitative (q)RT-PCR analyses allowed to determine the transcription level of genes involved in the plant defence response (phenylalanine ammonia-lyase, pal) and in the plant phytoalexin metabolism of PAW-treated materials. The number of symptomatic grapevine plants in vineyards was significantly reduced by the treatments. Transcriptional and post-transcriptional molecular analyses highlighted the PAW ability to enhance the expression of genes encoding the main enzymes involved in the phytoalexin biosynthetic pathway (flavonoids and stilbenes). The PAW ability to enhance some of the plant defence mechanisms also improving the health status of the treated plants was therefore experimentally demonstrated. After three years of trials the overall results demonstrated the possible use of PAW to reduce the disease severity, induce plant resistance both in open field and greenhouse, improving plant healthy status and grapevine yield production

    A new species of planthopper belonging to the genus Oecleus StÄl, 1862 (Hemiptera: Fulgoroidea: Cixiidae) from coconut palm (Cocos nucifera L) in Jamaica.

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    A new species of cixiid planthopper (Hemiptera: Fulgoroidea) in the genus Oecleus StÄl, Oecleus mackaspringi sp. n., is described from Spring Garden, Jamaica. This new taxon is associated with coconut palm (Cocos nucifera L.) and was found while surveying palm plots with active cases of lethal yellowing (LY). This is the first report of the genus Oecleus from Jamaica. Sequence data for the COI gene and 18S gene are also provided

    Transcriptional profiling of phytoplasma infected plants treated with plasma activated water (PAW).

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    Background. Phytoplasmas are insect-transmitted plant pathogenic prokaryotes, associated with severe diseases in agronomic important crops. Management of these diseases has mainly focused on insect vector chemical control and on infected plant rouging. There is therefore a strong need for effective and friendly control strategies for phytoplasma-associated diseases and the possibility to use plasma activated water (PAW) as sustainable and effective method to them was therefore evaluated. PAW is produced by treating distilled water with atmospheric pressure plasmas, inducing the production of reactive oxygen and nitrogen species (RONS) and pH reduction. PAW has good potential for bacterial decontamination, degradation of organic compounds and was shown to positively affect plant growth. Methods. Sterile deionized water (SDW) was exposed to a nanosecond pulsed dielectric barrier discharge, operating in ambient air for 10 min treatment with a peak voltage of 19 kV and a pulse repetition frequency of 1 kHz, which induced production of nitrates, nitrites and peroxides, and a pH decrease. Phytoplasma infected and healthy periwinkles micropropagated shoots were exposed to PAW for about 25 minutes and gene expression studies were then performed. The theses used were: shoots treated with PAW, Fosetyl aluminum (as positive control) and SDW (as negative control), with an exposition of about 25 minutes. Nine shoots for each thesis were then collected at 6 different times after treatment and stored at -80\ub0C. Quantitative RT-PCR analyses were carried out to determine the expression level of genes involved in the plant defense response. Parallel experiments were carried out treating grapevine plants in vineyards previously tested for the phytoplasma presence. Treatments were performed for three years injecting into the plant vascular tissues 10-20 ml of PAW or sterile distilled water (as control) on each selected plant for a total of 60 plants (40 with phytoplasmas and 20 without phytoplasmas). Results. Overexpression of selected genes involved in the phytoalexin metabolism was detected in the periwinkles micropropagated shoots treated with PAW in comparison with the shoots treated with Fosetyl-Al and distilled water. In the field trials, in a relevant number of cases, the PAW-treated symptomatic plants showed reduction of symptoms, while the SDW-treated and untreated plants did not show symptom reduction. No phytotoxicity was observed in the PAW treated grapevine and periwinkle plants. Conclusion. The results obtained showed the capability of PAW to enhance plant defence mechanisms and, as demonstrated in the field trials, confirmed its ability to improve the health status of the treated plant

    The Role of Alpha Oscillations among the Main Neuropsychiatric Disorders in the Adult and Developing Human Brain: Evidence from the Last 10 Years of Research

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    Alpha oscillations (7–13 Hz) are the dominant rhythm in both the resting and active brain. Accordingly, translational research has provided evidence for the involvement of aberrant alpha activ- ity in the onset of symptomatological features underlying syndromes such as autism, schizophrenia, major depression, and Attention Deficit and Hyperactivity Disorder (ADHD). However, findings on the matter are difficult to reconcile due to the variety of paradigms, analyses, and clinical phenotypes at play, not to mention recent technical and methodological advances in this domain. Herein, we seek to address this issue by reviewing the literature gathered on this topic over the last ten years. For each neuropsychiatric disorder, a dedicated section will be provided, containing a concise account of the current models proposing characteristic alterations of alpha rhythms as a core mechanism to trigger the associated symptomatology, as well as a summary of the most relevant studies and scientific con- tributions issued throughout the last decade. We conclude with some advice and recommendations that might improve future inquiries within this field

    A new species of planthopper in the genus Agoo Bahder & Bartlett (Hemiptera: Fulgoroidea: Derbidae) from coconut palm (Cocos nucifera L.) in Jamaica

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    A new species of the genus Agoo Bahder & Bartlett, Agoo beani sp. n. was found associated with coconut (Cocos nucifera L., Arecaceae) in Jamaica. This species was discovered as part of a survey of the Caribbean basin to document planthopper diversity on palms. Cytochrome c oxidase subunit I (COI) and 18S sequence data strongly support placement of the new species in Agoo. The morphological features of Omolicna cocoana Rodriguez-Leon & Hidalgo-Gato from Cuba are reviewed and this species transferred into the genus Agoo

    Plasma activated water as resistance inducer against bacterial leaf spot of tomato

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    Plant bacterial diseases are routinely managed with scheduled treatments based on heavy metal compounds or on antibiotics; to reduce the negative environmental impact due to the use of such chemical compounds, as pollution or selection of antibiotic resistant pathogens, the integrated control management is required. In the frame of a sustainable agriculture the use of bacterial antagonists, biological agents, plant defence response elicitors or resistant host plant genotypes are the most effective approaches. In this work, cold atmospheric pressure plasma (CAP) was applied to sterile distilled water, inducing the production of a hydrogen peroxide, nitrite and nitrate, and a pH reduction. In particular, an atmospheric pressure dielectric barrier discharge (DBD) has been used to produce plasma activated water (PAW), that was firstly assayed in in vitro experiments and then in planta through application at the root apparatus of tomato plants, against Xanthomonas vesicatoria (Xv), the etiological agent of bacterial leaf spot. Moreover, the transcription abundance of five genes related to the plant defense was investigated in response to PAW treatment. PAW did not show direct antimicrobial activity against Xv in in vitro experiments, but it enhanced the tomato plants defenses. It was effective in reducing the disease severity by giving relative protections of ca. 61, 51 and 38% when applied 1 h, 24 h and 6 days before the experimental inoculation, respectively. In addition, the experiments highlighted the pal gene involvement in response to the PAW treatments and against the pathogen; its transcription levels resulted significantly high from 1 to 48 h until their decrease 192 h after PAW application

    Identification of ‘Candidatus Phytoplasma’ species in “huanglongbing” infected citrus orchards in the Caribbean

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    “Huanglongbing” (HLB) is one of the most devastating diseases of citrus orchards worldwide. Samples from 183 citrus plants of different cultivars and rootstock/cultivar combinations, showing HLB symptoms in three Caribbean countries (Cuba, Jamaica, and Guadeloupe-France), were collected to verify the possible co-infection of ‘Candidatus Phytoplasma’ and ‘Candidatus Liberibacter’ species. The 64% of the samples resulted positive to the ‘Ca. L. asiaticus’ and the 27% to diverse ‘Ca. Phytoplasma’-related species, moreover about the 14% of the samples infected with ‘Ca. Liberibacter’ were also found positive to phytoplasmas, indicating the presence of mixed infection especially in the orchards located in Cuba. Moreover, in one of the samples from Jamaica mixed phytoplasma infection was detected. Moreover the detection of only phytoplasmas in 11 symptomatic citrus samples collected from Cuba and Guadeloupe without ‘Ca. Liberibacter’ detection, confirmed that the symptomatology cannot be the sole criterium to discriminate between the presence of the two pathogens, and molecular detection is necessary to identify single or mixed infections. Diaphorina citri insects collected from Cuba and Guadeloupe resulted infected with ‘Ca. L. asiaticus’ confirming its active role in the dissemination of the pathogen. Only one insect of the Cicadidae family, collected in Guadeloupe, was found positive for phytoplasma presence. Considering that the phytoplasmas belonging to some ‘Candidatus species’ were detected in the three countries in different citrus varieties, a relevant role as phytoplasma reservoir can be attribute to citrus orchards
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