Pseudomonas syringae pv. coryli, the Causal Agent of Bacterial Twig Dieback of Corylus avellana

ABSTRACT Thirty-eight bacterial strains isolated from hazelnut (Corylus avellana) cv. Tonda Gentile delle Langhe showing a twig dieback in Piedmont and Sardinia, Italy, were studied by a polyphasic approach. All strains were assessed by fatty acids analysis and repetitive sequence-based polymerase chain reaction (PCR) fingerprinting using BOX and ERIC primer sets. Representative strains also were assessed by sequencing the 16S rDNA and hrpL genes, determining the presence of the syrB gene, testing their biochemical and nutritional characteristics, and determining their pathogenicity to hazelnut and other plants species or plant organs. Moreover, they were compared with reference strains of other phytopathogenic pseudomonads. The strains from hazelnut belong to Pseudomonas syringae (sensu latu), LOPAT group Ia. Both fatty acids and repetitive-sequence-based PCR clearly discriminate such strains from other Pseudomonas spp., including P. avellanae and other P. syringae pathovars as well as P. syringae pv. syringae strains from hazelnut. Also, the sequencing of 16S rDNA and hrpL genes differentiated them from P. avellanae and from P. syringae pv. syringae. They did not possess the syrB gene. Some nutritional tests also differentiated them from related P. syringae pathovars. Upon artificial inoculation, these strains incited severe twig diebacks only on hazelnut. Our results justify the creation of a new pathovar because the strains from hazelnut constitute a homogeneous group and a discrete phenon. The name of P. syringae pv. coryli is proposed and criteria for routine identification are presented.     

Role of EDEM in the release of misfolded glycoproteins from the calnexin cycle

The mechanisms that determine how folding attempts are interrupted to target folding-incompetent proteins for endoplasmic reticulum-associated degradation (ERAD) are poorly defined. Here the alpha-mannosidase I-like protein EDEM was shown to extract misfolded glycoproteins, but not glycoproteins undergoing productive folding, from the calnexin cycle. EDEM overexpression resulted in faster release of folding-incompetent proteins from the calnexin cycle and earlier onset of degradation, whereas EDEM down-regulation prolonged folding attempts and delayed ERAD. Up-regulation of EDEM during ER stress may promote cell recovery by clearing the calnexin cycle and by accelerating ERAD of terminally misfolded polypeptides.     

Kiwellin, a modular protein from green and gold kiwi fruits: evidence of in vivo and in vitro processing and IgE binding

Kiwellin, an allergenic protein formerly isolated from green kiwi fruit, has been identified as the most abundant component of the gold kiwi species. A protein named KiTH, showing a 20 kDa band on reducing SDS-PAGE and 100% identity with the C-terminal region of kiwellin, has been identified in the extract of the ripe green species. In vitro treatment of purified kiwellin with the protease actinidin from green kiwi fruit originated KiTH and kissper, a recently described pore-forming peptide. Primary structure analysis and experimental evidence suggest that kiwellin is a modular protein with two domains. It may undergo in vivo proteolytic processing by actinidin, thus producing KiTH and kissper. When probed with sera recognizing kiwellin from green kiwi fruit, KiTH showed IgE binding, with reactivity levels sometimes different from those of kiwellin. The IgE-binding capacity of kiwellin from gold kiwi fruit appears to be similar to that of the green species.     

Characterization and degradation of lignin from steam explosion of pine and corn stalk of lignin: The role of superoxide ion and ozone

Steam explosion of corn stalk in the presence of 3% sulphuric acid at 200 °C for 5 min gave the highest recovery of lignin. Lignin has M_w = 2640 and M_z = 93,994. In the UV spectrum absorptions at λ = 231 and 280 nm were recorded. ¹H NMR spectrum of lignin showed signals attributable to cinnamaldehyde units, guaiacyl units, and syringyl units. Syringyl and guaiacyl units are in 1:1 ratio. ¹³C NMR spectrum showed signals for guaiacyl, syringyl, and p-hydroxyphenyl units. The spectrum showed a prevalence of guaiacyl units. The ¹³C NMR spectrum is in agreement with the presence of cinnamic units. The same characterization was performed on lignin from pine. The irradiation of lignin from pine from steam explosion process in the presence of oxygen, in conditions described for the formation of superoxide ion, for different irradiation time was followed isolating the lignin and determining the average molecular weight. The experiments showed that, until 8 h irradiation, M_n decreases, while M_w and M_z increases. After 8 h irradiation an inverse behaviour was observed, with an increase of M_n and a decrease of M_w and M_z. These results are in agreement with an initial polymerization process followed by a photoinduced degradation. Ozonization was carried out in acetonitrile–methanol solution. The reaction showed a zero-order kinetics. After 50 min the average molecular weight of lignin is the half. The reaction mixture was analyzed by using GC–MS. Oxalic acid was determined.     

Irrigation effects on quality, phenolic composition, and selected volatiles of virgin olive oils cv. Leccino

Field-grown olive trees (Olea europaea L. cv. Leccino) were used over two growing seasons to determine the effect of deficit irrigation regimes on virgin olive oil (VOO) quality. Drip irrigation was managed to maintain a predawn leaf water potential (PLWP): (a) higher than -1.1 MPa (full irrigation: FI); (b) between -1.0 and -3.3 MPa (deficit irrigation: DI); (c) higher than -4.2 MPa (severe deficit irrigation: SI). The fruit yield and oil yield of DI trees were over 90% of those of FI treatments in both years, respectively, whereas yields of SI trees ranged from 61 to 76%. The irrigation regime had minor effects on the free acidity, peroxide value, and fatty acid composition of VOO. The concentrations of phenols and o-diphenols in VOO were negatively correlated with PLWP. The concentrations of the dialdehydic form of decarboxymethyl elenolic acid linked to (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA), the isomer of the oleuropein aglycon (3,4-DHPEA-EA), and the dialdehydic form of decarboxymethyl elenolic acid linked to (p-hydroxyphenyl)ethanol (p-HPEA-EDA) were lower in FI than in SI treatments. The concentrations of lignans (+)-1-acetoxipinoresinol and (+)-1-pinoresinol were unaffected by the irrigation regime. The tree water status had a marked effect on the concentration of volatile compounds, such as the C(6)-saturated and unsaturated aldehydes, alcohols, and esters.     

Mixtures of organic amendments and biochar promote beneficial soil microbiota and affect Fusarium oxysporum f. sp. lactucae,Rhizoctonia solani and Sclerotinia minor disease suppression

The use of soil fumigants and fungicides to control soilborne pathogens is reduced due to awareness of their negative drawbacks. Long-term application of such agrochemicals negatively affects soil microbiota and reduces natural soil suppressiveness. We investigated long-term impacts of biochar and not-pyrogenic organic amendment (OAs: manure, alfalfa straw and glucose), on disease suppression compared with conventional management in three pathosystems: Fusarium oxysporum f. sp. lactucae (FOL)–lettuce, Rhizoctonia solani–tomato and Sclerotinia sclerotiorum–lettuce, by conditioning soil for 2 years. Soil analyses included pH, electrical conductivity, organic carbon, total nitrogen, C:N ratio, N-NO₃⁻, N-NH₄⁺, cation exchange capacity, available phosphorus, Ca²⁺, Mg²⁺, K⁺, Na⁺, fluorescein diacetate (FDA), and total and active limestone. Soil microbiota was characterized by combining BIOLOG EcoPlates with next-generation sequencing of 16S and 18S rRNA genes. Soil amended with OAs generally suppressed disease by S. sclerotiorum and FOL compared to fumigants and synthetic fertilizers. However, the incidence of R. solani infection was lower in soil treated with synthetic fertilizers than soil amended with OAs. EC, pH, C:N, N-NO₃⁻, N-NH₄⁺, FDA and BIOLOG were significantly correlated with disease, depending on pathosystem. Bacterial richness and diversity, presence of some genera like Acidobacteria, Chloracidobacteria, Solibacteres, Anaerolineae, Nitrospira and Deltaproteobacteria were negatively related to disease incidence of FOL and S. sclerotiorum, whereas damping-off caused by R. solani was negatively affected by the presence of Flavobacterium and Chitinofagha. Therefore, we concluded that long-term application of OAs can effectively improve soil suppressiveness and reduce disease incidence against root pathogens, although the effects vary considerably depending upon pathosystem.     

Evaluation of phenolic compounds in virgin olive oil by direct injection in high-performance liquid chromatography with fluorometric detection

Hydrophilic phenols are the most abundant natural antioxidants of virgin olive oil (VOO), in which tocopherols and carotenes are also present. The prevalent classes of hydrophilic phenols found in VOO are phenyl alcohols, phenolic acids, secoiridoids such as the dialdehydic form of decarboxymethyl elenolic acid linked to (3,4-dihydroxyphenyl)ethanol or (p-hydroxypheny1)ethanol (3,4-DHPEA-EDA or p-HPEA-EDA) and an isomer of the oleuropein aglycon (3,4-DHPEA-EA), lignans such as (+)-1-acetoxypinoresinol and (+)-pinoresinol, and flavonoids. A new method for the analysis of VOO hydrophilic phenols by direct injection in high-performance liquid chromatography (HPLC) with the use of a fluorescence detector (FLD) has been proposed and compared with the traditional liquid-liquid extraction technique followed by the HPLC analysis utilizing a diode array detector (DAD) and a FLD. Results show that the most important classes of phenolic compounds occurring in VOO can be evaluated using HPLC direct injection. The efficiency of the new method, as compared to the liquid-liquid extraction, was higher to quantify phenyl alcohols, lignans, and 3,4-DHPEA-EA and lower for the evaluation of 3,4-DHPEA-EDA and p-HPEA-EDA.     

Assessment of geographic variation by RAPD markers among Italian open-pollinated progenies of Populus alba L.

Random amplified polymorphic DNA (RAPD) analysis wasapplied to evaluate variation among provenances of white poplar(Populus alba L.) collected indifferent geographic areas in Italy. Fifteen decamer oligonucleotidesamplified a total of 71 distinct fragments of which 57(80% of the total observed) were polymorphic among53 plants of white poplar. Among provenances, the highest degree ofpolymorphism was detected in the population from Sinni river(62%), while the lowest level was recorded in thepopulation from Arno river (42%). Cluster(UPGMA) analysis was performed on the RAPD data and itdifferentiated the analysed plants in three distinct groupscorresponding to the Apennine, Southern and Northern Italian areas.The RAPD clusters were congruent with groups based on phenologicaltraits.     

Intergeneric relationships in the Australian Vitaceae: new evidence from cpDNA analysis

Taxa related to important agricultural species are likely to contain a considerable amount of potentially valuable genetic diversity. Nevertheless, before breeding programs or gene discovery projects can be initiated it is important to understand the phylogenetic relationships between the species involved. A component of a major gene discovery project in grapes at the Centre for Plant Conservation Genetics (Southern Cross University, Australia) is directed at the discovery of novel genes in native Vitaceae. As a result a study was conducted in order to assess the phylogenetic relationships between V. vinifera and the native members of the three major Australian genera: Cayratia, Cissus and Tetrastigma. CpDNA sequence analysis (from the trnL intron) adequately resolved intergeneric relationship between the majority of the species studied and provided some useful new information on the phylogenetic relationships within the Vitaceae. This preliminary project identified two species, C. hypoglauca and C. sterculiifolia, as being closely related to V. vinifera and worthy of further in-depth investigation.     

On the chemical composition and nutritional value of pleurotus taxa growing on umbelliferous plants (apiaceae)

Unpublished data on the chemical composition and nutritional value of Pleurotus mushrooms, growing on Umbelliferous plants (Apiaceae), are here reported. Cultivated basidiomata of four different Pleurotus taxa were analyzed in order to evaluate the composition in lipids, sugars, nitrogen, water, vitamins, ashes, and energetic values. The results showed that Pleurotus mushrooms are suitable in every type of diet thanks to their low caloric content, gastronomic value, vitamins, and mineral salt contents. The presence of a high content of vitamin B(12) and riboflavin in Pleurotus nebrodensis is noteworthy.