Osservazioni morfologiche e istologiche sugli organi di endosimbiosi batterica nelle femmine delle Cleonine (Coleoptera Curculionidae)

NEW MORPHOLOGICAL OBSERVATION OF THE FEMALE BACTERIAL POCKETS IN THE CLEONINS (COLEOPTERA CURCULIONIDAE) The typical “female transmission pockets” of the subf. Cleoninae were examined in nine species of the genera Cleonis, Larinus, Lixus and Rhinocyllus. They correspond to the female colleterial glands and are lacking in Larinus scolymi. Three morphological types of these glands were found: accordion-, sac- and bush-like. Observed in Lixus punctiventris, the epithelium of these organs exhibits largely nucleated cells, each rich of microvilli at apical end. The dense bacterial contents include a large percentage of paired rods, each 2-3 μm long. Key words: Curculionidae, Cleoninae, bacteria, accessory glands, fine structure.Viene documentata la diversità anatomica delle sacche batteriche femminili nella subf. Cleoninae, dove è insediata una ricca flora bacillare. Dati istologici sono tratti dallo studio al microscopio elettronico a trasmissione delle ghiandole di Lixus punctiventris. Si rileva l’assenza delle sacche in Larinus scolymi. Parole chiave: Curculionidi, Cleoninae, batteri, ghiandole accessorie, ultrastruttura.

How Agrobacterium rhizogenes triggers de novo root formation in a recalcitrant woody plant: an integrated histological, ultrastructural and molecular analysis

Adventitious rooting might be induced in recalcitrant woody genotypes by infection with Agrobacterium rhizogenes, and, in some cases, might also require exogenous auxin. The objective of the present study was to determine how agrobacteria trigger root formation in the stem of a recalcitrant woody microcutting, which cytological events result from the combined presence of infection and exogenous auxin, and which types of roots are induced by infection. Microcuttings of a recalcitrant walnut (Fuglans regia), infected or not with A. rhizogenes strain 1855, were cultured with either indolebutyric acid (IBA), IAA, or without exogenous hormones, to induce rhizogenesis. They were cytohistologically and ultrastructurally investigated at various times in culture. Southern blot and PCR analyses were performed to verify the frequency of transgenic, chimeric and bacterium-containing roots. The infection was sufficient per se to stimulate rhizogenesis. Rooting on the infected cuttings was enhanced by exogenous IBA, which accelerated and increased root meristemoid formation, in comparison with without hormone treatment. Meristemoids were organized both directly by the cambial cells and indirectly by the callus, and showed a pluricellular origin. Inter and intracellular bacteria were observed in the stem throughout the culture period (30 d). They were preferentially present in the vessels, and mainly in those showing polyphenol deposition. In the infected IAA-treated cultures, a high level of secondary xylem formation occurred instead of rhizogenesis. Nontransformed roots were preferentially produced by the infected cuttings treated with the auxins. Bacterium-containing and chimeric roots were produced by infected cuttings independently of the treatment. Thus, in a recalcitrant walnut, nontransformed root meristemoids are stimulated by combining infection and exogenous indolebutyric acid. Furthermore, the persistence of bacteria in the stem during the culture and the pluricellular origin of the meristemoids explain the presence of the bacterium-containing and chimeric roots

Cucumber mosaic virus Is Unable to Self-Assemble in Tobacco Plants When Transmitted by Seed

Cucumber mosaic virus (CMV), which has great impact on agronomic production worldwide, is both aphid and seed transmitted. Although the mechanisms of aphid transmission have been widely studied, those underlying the ability of CMV to survive and remain infectious during the passage from one generation to the next through the seeds are still to be clarified. Moreover, the viral determinants of seed transmission rate are poorly understood. Three viral genotypes produced from same RNA 1 and 2 components of CMV-Fny but differing in RNA 3 (the wild type CMV-Fny, a pseudorecombinant CMV-Fny/CMV-S and a chimeric CMV previously obtained by our group, named F, FS and CS, respectively) were propagated in Nicotiana tabacum cv Xanthi plants in order to assess differences in tobacco seed transmission rate and persistence through plant generations in the absence of aphid transmission. Seed-growth tests revealed CMV infection in the embryos, but not in the integuments. Seedlings from seed-growth tests showed the presence of all considered viruses but at different rates: from 4% (F, FS) to 16% (CS). Electron microscopy revealed absence (CS) of viral particles or virions without the typical central hole (F and FS). In agreement, structural characteristics of purified CMV particles, assessed by circular dichroism spectroscopy, showed anomalous spectra of nucleic acids rather than the expected nucleoproteins. These alterations resulted in no seed transmission beyond the first plant generation. Altogether, the results show for the first time that correct virion assembly is needed for seed infection from the mother plant but not to seedling invasion from the seed. We propose that incorrect virion formation, self-assembly and architecture stability might be explained if during the first stages of germination and seedling development some tobacco seed factors target viral regions responsible for protein-RNA interactions

Infectivity and Transmission of Xylella fastidiosa by Philaenus spumarius (Hemiptera: Aphrophoridae) in Apulia, Italy

Discovery of Xylella fastidiosa from olive trees with "Olive quick decline syndrome" in October 2013 on the west coast of the Salento Peninsula prompted an immediate search for insect vectors of the bacterium. The dominant xylem-fluid feeding hemipteran collected in olive orchards during a 3-mo survey was the meadow spittlebug, Philaenus spumarius (L.) (Hemiptera: Aphrophoridae). Adult P. spumarius, collected in November 2013 from ground vegetation in X. fastidiosa-infected olive orchards, were 67% (40 out of 60) positive for X. fastidiosa by polymerase chain reaction (PCR) assays. Euscelis lineolatus Brulle were also collected but tested negative for the pathogen. Transmission tests with P. spumarius collected from the Salento area were, therefore, conducted. After a 96-h inoculation access period with 8 to 10 insects per plant and a 30-d incubation period, PCR results showed P. spumarius transmitted X. fastidiosa to two of five periwinkle plants but not to the seven olive plants. Sequences of PCR products from infected periwinkle were identical with those from X. fastidiosa-infected field trees. These data showed P. spumarius as a vector of X. fastidiosa strain infecting olives trees in the Salento Peninsula, Italy

Cytopathic effects incited by viroid RNAs and putative underlying mechanisms

[EN] Viroids are infectious agents identified only in plants so far. In contrast to viruses, the genome of viroids is composed of a tiny circular RNA (250-400 nt) not coding for proteins, but containing in its compact structure all the information needed for parasitizing the transcriptional and RNA trafficking machineries of their hosts. Viroid infections are frequently accompanied by cellular and developmental disorders that ultimately result in macroscopic symptoms.The molecular events linking the structural domains of viroid RNAs with cellular and macroscopic alterations remain largely unexplored, although significant progress has been lately achieved in one specific viroid-host combination, highlighting the ability of viroids to strongly interfere with their host RNA regulatory networks. Cytopathic effects induced by nuclear-replicating viroids, which were investigated since early studies on viroids, consist in irregular proliferations of cell membranes (paramural bodies or plasmalemmasomes), cell wall distortions, and chloroplast malformations. Different alternatives have been proposed regarding how these cytological alterations may influence the onset of macroscopic symptoms. Recently, the cytopathology and histopathology incited by a chloroplast-replicating viroid have been investigated in depth, with defects in chloroplast development having been related to specific molecular events that involve RNA silencing and impairment of chloroplast ribosomal RNA maturation. On this basis, a tentative model connecting specific cytopathologic alterations with symptoms has been put forward. Here, early and more recent studies addressing this issue will be reviewed and reassessed in the light of recent advances in the regulatory roles of small RNAs.Research in Beatriz Navarro and Francesco Di Serio laboratory is supported by a dedicated grant (CISIA) of the Ministero dell'Economia e Finanze Italiano to the CNR (Legge n. 191/2009). Research in Ricardo Flores laboratory is presently supported by grant BFU2011-28443 from the Ministerio de Ciencia e Innovacion of Spain. We apologize for not quoting the original work of many authors due to space limitations.Di Serio, F.; De Stradis, A.; Delgado Villar, SG.; Flores Pedauye, R.; Navarro, B. (2013). Cytopathic effects incited by viroid RNAs and putative underlying mechanisms. Frontiers in Plant Science. 3:288-1-288-7. https://doi.org/10.3389/fpls.2012.00288288-1288-7

Soluble beta amyloid evokes alteration in brain norepinephrine levels: role of nitric oxide and interleukin-1

Strong evidence showed neurotoxic properties of beta amyloid (Aβ) and its pivotal role in the Alzheimer's disease (AD) pathogenesis. Beside, experimental data suggest that Aβ may have physiological roles considering that such soluble peptide is produced and secreted during normal cellular activity. There is now suggestive evidence that neurodegenerative conditions, like AD, involve nitric oxide (NO) in their pathogenesis. Nitric oxide also possess potent neuromodulatory actions in brain regions, such as prefrontal cortex (PFC), hippocampus (HIPP), and nucleus accumbens (NAC). In the present study, we evaluated the effect of acute Aβ injection on norepinephrine (NE) content before and after pharmacological manipulations of nitrergic system in above mentioned areas. Moreover, effects of the peptide on NOS activity were evaluated. Our data showed that 2 h after i.c.v. soluble Aβ administration, NE concentrations were significantly increased in the considered areas along with increased iNOS activity. Pre-treatment with NOS inhibitors, 7-Nitroindazole (7-NI), and N6-(1-iminoethyl)-L-lysine-dihydrochloride (L-NIL), reversed Aβ-induced changes. Ultimately, pharmacological block of interleukin1 (IL-1) receptors prevented NE increase in all brain regions. Taken together our findings suggest that NO and IL-1 are critically involved in regional noradrenergic alterations induced by soluble Aβ injection

The impact of xylem geometry on olive cultivar resistance to Xylella fastidiosa: an image‐based study

Xylella fastidiosa is a xylem-limited plant pathogen infecting many crops globally and is the cause of the recent olive disease epidemic in Italy. One strategy proposed to mitigate losses is to replant susceptible crops with resistant varieties. Several genetic, biochemical and biophysical traits are associated to X. fastidiosa disease resistance. However, mechanisms underpinning resistance are poorly understood. We hypothesize that the susceptibility of olive cultivars to infection will correlate to xylem vessel diameters, with narrower vessels being resistant to air embolisms and having slower flow rates limiting pathogen spread. To test this, we scanned stems from four olive cultivars of varying susceptibility to X. fastidiosa using X-ray computed tomography. Scans were processed by a bespoke methodology that segmented vessels, facilitating diameter measurements. Though significant differences were not found comparing stem-average vessel section diameters among cultivars, they were found when comparing diameter distributions. Moreover, the measurements indicated that although vessel diameter distributions may play a role regarding the resistance of Leccino, it is unlikely they do for FS17. Considering Young–Laplace and Hagen–Poiseuille equations, we inferred differences in embolism susceptibility and hydraulic conductivity of the vasculature. Our results suggest susceptible cultivars, having a greater proportion of larger vessels, are more vulnerable to air embolisms. In addition, results suggest that under certain pressure conditions, functional vasculature in susceptible cultivars could be subject to greater stresses than in resistant cultivars. These results support investigation into xylem morphological screening to help inform olive replanting. Furthermore, our framework could test the relevance of xylem geometry to disease resistance in other crops