Detection and identification of Phytophthora species in southern Italy by RFLP and sequence analysis of PCR-amplified nuclear ribosomal DNA.

In four neighbouring regions of southern Italy, Basilicata, Campania, Apulia and Calabria, pepper and zucchini plants showing Phytophthora blight symptoms, tomato plants with either late blight or buckeye rot symptoms, plants of strawberry showing crown rot symptoms and declining clementine trees with root and fruit rot were examined for Phytophthora infections by means of polymerase chain reaction (PCR) assays, using primers directed to nuclear ribosomal DNA (rDNA) repeat sequences. All diseased plants and trees examined tested positive. The detected fungal-like organisms were differentiated and characterized on the basis of primer specificity as well as through extensive restriction fragment length polymorphism (RFLP) and sequence analysis of PCR-amplified rDNA. Phytophthora capsici was identified in diseased pepper and zucchini plants, P. infestans was identified in tomato with late blight symptoms whereas buckeye rot-affected tomatoes and diseased strawberry plants proved to be infected by P. nicotianae and P. cactorum, respectively. Declining clementine trees were infected with P. citrophthora and P. nicotianae in about the same proportion. Also, thirty-one pure culture-maintained isolates of Phytophthora which had previously been identified in southern Italy by traditional methods but were never examined molecularly, were examined by RFLP and sequence analysis of PCR-amplified nuclear rDNA. Among these, an isolate from gerbera which had previously been identified by traditional methods only at genus level, was assigned to P. tentaculata. For the remaining pure culture-maintained isolates examined, the molecular identification data obtained corresponded with those delineated by traditional methods. Most of the diseases examined were already known to occur in southern Italy but the pathogens were molecularly detected and fully characterized at nuclear rDNA repeat level only from other geographic areas, very often outside Italy. A new disease to southern Italy was the Phytophthora blight of zucchini. This is also the first report on the presence and molecular identification of P. tentaculata from Italy

Effect of irrigation regimes and artificial mycorrhization on insect pest infestations and yield in tomato crop

A 2-year field experiment was carried out to test the effect of root symbionts treatments in combination with different watering levels on tomato yield and pest infestation rates. A split-plot experimental design was followed, where the main treatments were three irrigation regimes, and the subplot factor was the mycorrhizal treatment (two mycorrhizal treatments [M1 and M2] and the control). The M1 treatment consisted in the use of a commercial preparation (Micosat F; CCS Aosta, Italy) containing a mixture of vesicular-arbuscular mycorrhizae (VAM), bacteria of the rhizosphere and saprophytic fungi, while M2 treatment used only arbuscular mycorrhizal fungi. Insect pests sampled in the field during the 2 years of experiment were all sap-feeders (Trialeurodes vaporariorum, Macrosiphum euphorbiae, Frankliniella occidentalis and an unidentified species of leafhopper). Results did not show any impact of root symbionts on pests, whereas water deficit significantly reduced plant infestation rates. Both mycorrhization treatments and water supply resulted in a significantly positive effect on crop yield

Evaluation of Resistance to TSWV and Agronomic Behaviour of Some TSWV-Resistant Tomato Genotypes in Southern Italy

A two-year research was carried out in Ofanto valley (Basilicata region, southern Italy) in 2006-2007, for evaluating agronomic behaviour of new processing tomato genotypes resistant to tomato spotted wilt virus (TSWV) and ascertaining their effective resistance to the virus. Five TSWV-resistant genotypes (cultivars and lines) were compared in each year the TSWV susceptible cultivar ‘Perfectpeel’ was used as a control. Two transplant dates were adopted in both years: 1) mean-early and 2) mean-late. A split-plot design with 3 reps was followed in the two years. Yield and fruit quality were considered as agronomic traits. About virological aspects, field observations and laboratory analysis (ELISA, IME) were carried out during crop cycles. Phytoplasma infection frequency was also assessed for the same plants. The control cultivar ‘Perfectpeel’ resulted highly productive in both years that were however characterized by low incidence of virus infections; beside, among new genotypes ‘Vespro’ and ‘Suerte’ gave a good yield, while ‘Candia’ and ‘Isi 23259’ exhibited high fruit quality. Virological studies showed that the new processing tomato genotypes were indeed TSWV-resistant. Finally, phytoplasma infections had a dissimilar incidence among plants of the tested genotypes

Growth and yield promoting effect of artificial mycorrhization combined with different fertiliser rates on field-grown tomato

Combination of plant inoculation with a commercial mycorrhizal formulation with half or full fertiliser application rates was evaluated for the effects on plant growth and yield and mycorrhization occurrence throughout two consecutive field tomato crops in southern Italy. Mycorrhizal formulation was inoculated on tomato seedling roots both in the nursery and after transplant. Inoculated tomato seedlings were significantly larger than non-inoculated seedlings less than 30 days after the first inoculation in the nursery. Above ground dry biomass and stem number of inoculated plants were found to be higher also at the end of each crop. Positive effects of mycorrhizal inoculation were extended also to marketable yield of both crops, mainly due to an increased number and weight of clusters and fruits. Mycorrhizal treatment also improved crop earliness, seen in terms of anticipating plant flowering, increasing first harvest yield, and reducing average harvesting time compared to non-inoculated plants. Both rates of mineral fertilisers positively affected tomato growth and marketable yield, but did not influence fruit quality parameters. No significant interaction was found between mineral fertilisation and plant mycorrhization. Crop inoculation with mycorrhizal formulations could reduce the amounts of fertilisers and pesticides being used, and could represent a sustainable technique to improve crop yield and profitability

Cytotoxic Activity of Origanum Vulgare L. on Hepatocellular Carcinoma cell Line HepG2 and Evaluation of its Biological Activity

The potential of plant essential oils (EOs) in anticancer treatment has recently received many research efforts to overcome the development of multidrug resistance and their negative side effects. The aims of the current research are to study (i) the cytotoxic effect of the crude EO extracted from Origanum vulgare subsp hirtum and its main constituents (carvacrol, thymol, citral and limonene) on hepatocarcinoma HepG2 and healthy human renal cells HEK293; (ii) the antibacterial and phytotoxic activities of the above EO and its main constituents. Results showed that cell viability percentage of treated HepG2 by EO and its main constituents was significantly decreased when compared to untreated cells. The calculated inhibition concentration (IC50) values for HepG2 were lower than healthy renal cells, indicating the sort of selectivity of the studied substances. Citral is not potentially recommended as an anticancer therapeutic agent, since there are no significant differences between IC50 values against both tested cell lines. Results showed also that oregano EO and its main constituents have a significant antibacterial activity and a moderate phytotoxic effect. The current research verified that oregano EO and its main constituents could be potentially utilized as anticancer therapeutic agents

Use of plant growth promoting bacteria (PGDB) for promoting tomato growth and its evaluation as biological control agent.

The plant growth promoting effect of some bacteria usable to control plant diseases has a potential for resolving technical problems of plant production. The effects of Burkholderia gladioli pv. agaricicola ICMP11096 on development of tomato seedlings development and control of their infection by Fusarium oxysporum and Sclerotinia sclerotiorum were evaluated in the present study. Bacterized plants showed a higher shoot and root weight and a more extended root system in terms of total length and root density than non-bacterized plants. The bacter-izing treatments gave rise to significant reduction of disease symptoms such as leaf wilting induced by F. oxysporum infection and/or root ne-crosis and leaf yellowing by S. sclerotiorum. The potential use of Burkholderia gladioli pv. agaricicola ICMP11096 in biocontrol of fungal patho-gens and to enhance seedling growth parameters is underlined as a tool to achieve a high commercial quality of nursery tomato plants