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Spiroplasma spp.: a plant, arthropod, animal and human pathogen
Full text linkMollicutes is a class of smallest and free-living bacteria. They have no cell wall and their plasma membrane contains cholesterol; nevertheless, cellular organization does not dif- fer from that of other prokaryotes. They are used as simple model systems for studying general biological problems, such as those concerning membrane structure and func- tions, symbiosis between arthropods and microrganisms, animal and plant pathogens. Mollicutes includes the family of Spiroplamataceae, which contains Spiroplasma genus, a group of species associated, in different manner, with arthropods (insects, mites, crusta- ceans). Spiroplasma species can be commensals or parasites and even be involved in more close symbiosis, such as synergism or mutualism. Out of 38 described Spiroplasma spe-cies, only three have been associated with plant diseases and three with arthropod dis-eases. Moreover, some species have been related to animal diseases, such as transmissible spongiform encephalopathy (TSE), and their role in human disease has been assessed. The chapter describes the taxonomic situation of the genus and reports the most impor-tant diseases due to the presence of Spiroplasma in different living organisms with special emphasis on citrus in which it causes one of the most economically damaging infectious diseases in a number of citrus growing areas worldwide
A tracheomycosis as a tool for studying the impact of stem xylem dysfunction on leaf water status and gas exchange in Citrus aurantium L.
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Phytotoxic Metabolites Isolated from Neufusicoccum batangarum, the Causal Agent of the Scabby Canker of Cactus Pear (Opuntia ficus-indica L.)
No full textSix phytotoxins were obtained from the culture filtrates of the ascomycete Neofusicoccum batangarum, the causal agent of the scabby canker of cactus pear (Opuntia ficus-indica L.) in minor Sicily islands. The phytotoxins were identified as (-)-(R)-mellein (1); (±)-botryoisocoumarin A (2); (-)-(3R,4R)- and (-)-(3R,4S)-4-hydroxymellein (3 and 4); (-)-terpestacin (5); and (+)-3,4-dihydro-4,5,8-trihydroxy-3-methylisocoumarin, which we named (+)-neoisocoumarin (6). This identification was done by comparing their spectral and optical data with those already reported in literature. The absolute configuration (3R,4S) to (+)-neoisocoumarin (6) was determined using the advanced Mosher method. All six metabolites were shown to have phytotoxicity on the host (cactus pear) and non-host (tomato) plants, and the most active compounds were (±)-botryoisocoumarin A (2), (-)-terpestacin (5), and (+)-neoisocoumarin (6)
Development of quantitative PCR detection methods for phytopathogenic fungi and oomycetes
No full textIn recent years quantitative PCR (qPCR) detection
methods have been widely utilised to detect phytopathogenic
fungi and oomycetes and have greatly contributed
to the advancement of knowledge in plant
pathology. However, major drawbacks and common errors,
most typical of earlier reports, still affect many
methods currently available in the literature. Errors can
be made throughout the entire process for the development
of qPCR methods, at the level of selection of appropriate
DNA extraction and purification protocols,
identification of suitable target regions, choice of the
chemistry, design and validation of specific primers and
probes, analysis of sensitivity, choice of an absolute
and/or relative quantification approach and analysis of
the risk of detecting target DNA from dead sources. In
the present review the above mentioned steps are
analysed, highlighting their critical aspects and providing
a practical guide for the users
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