Different polyphenolic parenchyma cell and phloem axial resin duct-like structures formation rates in Cupressus sempervirens clones infected with Seiridium cardinale

The aim of this study was the characterization of constitutive and induced defence mechanisms in the bark tissues of Cupressus sempervirens before and after infection with the bark fungus Seiridium cardinale that is responsible for Cypress Canker Disease. The time-course development of polyphenolic parenchyma cells (PP cells) and phloem axial resin ducts PARDs(PARD) like structures) in the phloem was investigated in two C. sempervirens clones, one resistant and one susceptible to the disease, through anatomycal and hystologycal observations carried out by light microscope during a 19 days trial. PP cells were constitutively more abundant in the canker resistant clone compared to the susceptible clone, while PARDsPARD-like structures were not present in the bark of untreated plants of both clones. PP cells increased in both clones as a response to infection, but in the resistant clone they were more abundant 5 and 12 days after inoculation. Following inoculation, PARDsPARD-like structures appeared in the phloem after 5 days in the resistant clone and only after 12 days in the susceptible clone. Even the number of secretory cells (surrounding the PARDsPARD-like structures) was higher in the R clone 5 and 12 days after inoculation compared to the S clone. These observations demonstrate a faster phloem response of the resistant clone in the early phase of the infection. This may slow down initial growth of the fungus contributing to the resistance mechanism.

Starch Catabolism Revealed during Secondary Metabolite Released Under Vascular Streak Dieback Infections in Cocoa (Theobroma cacao L)

This study aimed to study the profile of starch content in cocoa leaf and phytoalexin production based on GC-MS analysis at several stages of VSD pathogen infection. Research was conducted on January – October 2015 at Kaliwining Experimental Field, Indonesian Coffee and Cocoa Research Institute, Jember, East Java. The research was designed based on a Completely Randomized Block Design with two factors with three replications. The first factor was clone, i.e. the resistant clone (Scavina 6) and susceptible (TSH 858) to VSD infection. The second factor was the level of O. theobromae infection, i.e. pre-infection, early infection, and late infection. Starch catabolism revealed during Vascular Streak Dieback infections in Cacao. Starch content in Sca 6 (resistant clone) in late infection decreased 24,33 % than healthy condition (no infection), however, starch content in TSH 858 (succeptible clone) in late infection decreased only 9,63 % than healthy condition (no infection). This indicated that starch catabolism rate on resistant clone was higher than susceptible clone. Some secondary metabolites releases under Vascular Streak Dieback i.e. I-limonene, eugenol and coumaran. Scavina 6 (resistant clone) had higher concentration of eugenol and coumaran than TSH 858 (susceptible clone). I-limonene compound, TSH 858 (Susceptible clone) had higher concentration than Scavina 6. I-Limonene concentration increased in lined with the severity of pathogen infection. There were an negative correlation between starch content with contentration of I-limonene (R= - 0,74), concentration of Eugenol (R= - 0,44), and contentration of Coumaran.

New 4-aminoquinolines as moderate inhibitors of P. falciparum malaria

Synthesis of novel aminoquinoline derivatives has been accomplished and their activity against malaria strains has been examined. The compounds showed moderate in vitro antimalarial activity against two P. falciparum strains, 3D7 (CQ susceptible clone) and Dd2 (CQ resistant clone). Three amino-quinolines were further examined for antimalarial efficacy in a mouse model using a modified Thompson test. In this model, mice were infected with P. berghei-infected red blood cells, and drugs were administered orally. Anti-malarial 3 was found toxic at a dose of 320 (mg/kg)/day in 3/6 mice, however, 2/6 mice of the same group survived through day 31, and one of them was cured.

Terpenoid Accumulation Links Plant Health and Flammability in the Cypress-Bark Canker Pathosystem

To explore the possible relationship between diseased trees and wildfires, we assessed the flammability of canker-resistant and susceptible common cypress clones that were artificially infected with Seiridium cardinale compared to healthy trees. This study explored the effect of terpenoids produced by the host plant in response to infection and the presence of dead plant portions on flammability. Terpenoids were extracted and quantified in foliage and bark samples by gas chromatography–mass spectrometry (GC–MS). A Mass Loss Calorimeter was used to determine the main flammability descriptors. The concentration of terpenoids in bark and leaf samples and the flammability parameters were compared using a generalized linear mixed models (GLMM) model. A partial least square (PLS) model was generated to predict flammability based on the content of terpenoid, clone response to bark canker and the disease status of the plants. The total terpenoid content drastically increased in the bark of both cypress clones after infection, with a greater (7-fold) increase observed in the resistant clone. On the contrary, levels of terpenoids in leaves did not alter after infection. The GLMM model showed that after infection, plants of the susceptible clone appeared to be much more flammable in comparison to those of resistant clones, showing higher ignitability, combustibility, sustainability and consumability. This was mainly due to the presence of dried crown parts in the susceptible clone. The resistant clone showed a slightly higher ignitability after infection, while the other flammability parameters did not change. The PLS model (R2Y = 56%) supported these findings, indicating that dead crown parts and fuel moisture content accounted for most of the variation in flammability parameters and greatly prevailed on terpenoid accumulation after infection. The results of this study suggest that a disease can increase the flammability of trees. The deployment of canker-resistant cypress clones can reduce the flammability of cypress plantations in Mediterranean areas affected by bark canker. Epidemiological data of diseased tree distribution can be an important factor in the prediction of fire risk.

Penicillin-Binding Protein Typing, Antibiotic Resistance Gene Identification, and Molecular Phylogenetic Analysis of Meropenem-Resistant Streptococcus pneumoniae Serotype 19A-CC3111 Strains in Japan

ABSTRACT Since the introduction of pneumococcal conjugate vaccines, the prevalence of non-meropenem-susceptible pneumococci has been increasing in Japan. In an earlier study, we demonstrated that multidrug-resistant serotype 15A-ST63 in Japan has a specific pbp1a sequence (pbp1a-13) that could promote meropenem resistance. To trace the origin of pbp1a, we analyzed isolates of serotype 19A-CC3111, which is the most prevalent non-meropenem-susceptible clone in Japan. We analyzed a total of 119 serotype 19A-CC3111 strains recovered in Japan using whole-genome sequencing. Of the 119 isolates, 53 (44.5%) harbored pbp1a-13, indicating that the clone may be the primary reservoir of the pbp1a type and that the pbp1a region may be horizontally transferred between different serotype strains. The single acquisition of pbp1a-13 seemed to cause only penicillin resistance and not multidrug resistance; a combination of penicillin-binding protein (PBP) recombination in the pbp2b and/or pbp2x region(s) with acquisition of pbp1a-13 caused multidrug resistance. Conserved amino acid motif analysis suggested that the pbp1a 370SXXK, pbp2b 448SXN, and pbp2x 337SXXN motifs were the candidates for amino acid substitutions increasing the MICs of meropenem, cefotaxime, and penicillin. We identified a specific clone that was correlated with multidrug resistance, although no correlation was observed between phylogenetic trees generated using core genomes and those generated with only the cps locus. All tested isolates were highly erythromycin resistant, and most harbored mefE within macrolide efflux genetic assembly (MEGA) elements and ermB within Tn917, which was inserted within Tn916 and exhibited a structure identical to that of Tn2017.

Analysis of Secondary Metabolites as Potential Phytoalexins, Their Secretion Sites and Proposed Resistance Markers to Vascular Streak Dieback in Theobroma cacao L.

Study on resistance mechanism to vascular-streak dieback (VSD) disease in cacao (Theobroma cacao L.) is limited due to the lack of fungal spores for artificial inoculation. This research was conducted to study the production of secondary metabolites that appear to be evidence of defense signaling in resistant clone of Sca 6 and susceptible clone of TSH 858 to Ceratobasidium theobromae natural infection. A fungal staining method was employed to detect C. theobromae hyphae at early infection stages, before VSD symptoms appear. Metabolite profiling was analyzed using pyrolysis gas chromatography mass spectrometry (Py-GCMS) at pre-, early and late stages of C. theobromae infection. Histochemical and anatomical characteristics of both healthy and infected leaves were also observed to identify the accumulation sites of secondary metabolites on and in cocoa leaf tissues. The results confirmed that fungal staining using trypan blue can detect early stages of C. theobromae infection; at the 14th week (on susceptible seedlings) and the 18th week (on resistant clones), following placement of the seedlings under infected cacao plants. Phenylpropanoid biosynthesis, terpenoid biosynthesis, environmental information processing signal transduction pathways, and aromatic biodegradation were detected as important metabolite pathways during defense mechanism. I-limonene (terpenoid), p-ethylguaiacol (phenols) and 2.3 dihidrobenzofuran (heterocyclic compounds) were proposed as an active defense produced by the host after infected by pathogen mainly on late infection of C. theobromae. Terpenoid and phenol compounds were accumulated on the glandular trichomes, idioblast of upper and bottom epidermis, phloem vessel and cortex idioblast of cacao leaves. Epidermis thickness of resistant clone was significantly greater than that of susceptible clone on both surfaces. Leaf epidermis tissue and the accumulated compounds in epidermis idioblast may act as the physical and biochemical markers of cocoa resistance to VSD.

Plant growth regulators in poplar clones differing in resistance to the fungus Ceratocystis fimbriata Ell. et Haist

In poplar clones with different resistance to the fungus <i>Ceratocystis fimbriata</i> growth of shoots, intensity of transpiration and the level of endogenous growth regulators were determined. More resistant clones, <i>Populus</i> 'Robusta' and P. 'PK-136-2' (<i>P. nigra</i> 'Italica': x <i>P. laurifolia</i>) had more intensive growth of shoots, higher water content in leaves and a lower intensity of transpiration than the more susceptible clone, - <i>P. 'NE-42'</i> (<i>P. maximowiczi</i> x <i>P. trichocarpa</i>). The leaves of the more resistant clones contained more auxins (IAA) and cytokinins, especially zeatin, and less growth inhibitors (ABA) than those of the susceptible one. The level of plant growth regulators and/or the relations betweeen them may be responsible for the different poplar resistance to <i>C. fimbriata</i>.

An Ertapenem-Resistant Extended-Spectrum-β-Lactamase-Producing Klebsiella pneumoniae Clone Carries a Novel OmpK36 Porin Variant

ABSTRACT Carbapenem-resistant Klebsiella pneumoniae caused an outbreak in a hospital in Rome, Italy. The clinical isolates were tested by antimicrobial susceptibility testing, pulsed-field gel electrophoresis, multilocus sequence typing, plasmid typing, and β-lactamase identification. The OmpK35 and OmpK36 porins were analyzed by SDS-PAGE, and their genes were amplified and sequenced. Complementation experiments were performed using a recombinant unrelated ompK36 gene. An ertapenem-resistant and imipenem- and meropenem-susceptible clone was identified and assigned to the sequence type 37 lineage by MLST; it carried SHV-12 and CTX-M-15 ESBLs, did not produce the OmpK35 due to a nonsense mutation, and expressed a novel OmpK36 variant (OmpK36V). This variant showed two additional amino acids located within the L3 internal loop, one of the highly conserved domains of the protein. Two isolates of the same clone also exhibited resistance to imipenem and meropenem, due to the loss of OmpK36 expression by a nonsense mutation occurring in the ompK36V variant gene. These were the first carbapenem-resistant K. pneumoniae isolates identified within the hospital. Screening for the ompK36V gene of unrelated K. pneumoniae isolates derived from patients from 2006 to 2009 demonstrated the high frequency of this gene variant as well as its association with ertapenem resistance, reduced susceptibility to meropenem, and susceptibility to imipenem.

Strong parasitoid-mediated selection in experimental populations of aphids

Clonal diversity in asexual populations may be maintained if different clones are favoured under different environmental conditions. For aphids, parasitoids are an important variable of the biotic environment. To test whether parasitoids can mediate selection among host clones, we used experimental populations consisting of 10 clones of the peach–potato aphid, Myzus persicae , and allowed them to evolve for several generations either without parasitoids or in the presence of two species of parasitoid wasps. In the absence of parasitoids, strong shifts in clonal frequencies occurred, mostly in favour of clones with high rates of increase. The parasitoid Diaeretiella rapae hardly affected aphid densities but changed the outcome of competition by favouring one entirely resistant clone and disfavouring a highly susceptible clone. Aphidius colemani , the more infective parasitoid, strongly reduced aphid densities and dramatically changed host clonal frequencies. The most resistant clone, not a successful clone without parasitoids, became totally dominant. These results highlight the potential of temporal or spatial variation in parasitoid densities to maintain clonal diversity in their aphid hosts.