The ecological, economic and social values of the ectomycorrhizal fungi of the black truffle found in the rural Mediterranean are well known. The inoculation of Pinus halepensis seedlings with mycorrhizal fungi and rhizobacteria can improve the morphology and physiology of the seedlings and benefit the regeneration of arid regions and the reintroduction of inocula of mycorrhizal fungi into these areas. Some rhizobacteria can improve the establishment and functioning of ectomycorrhizal symbiosis. In this study, seedlings of P. halepensis were inoculated with the mycorrhizal fungus Tuber melanosporum and the rhizobacteria Pseudomonas fluorescens CECT 844 under non-limiting greenhouse conditions. Five months after inoculation, we analysed the growth, water parameters (osmotic potential at saturation, osmotic potential at turgor loss and modulus of elasticity), concentrations of mycorrhizal colonies, nutrient concentration and nutrient contents (N, P, K, Ca, Mg and Fe) in roots and aerial parts of the seedlings. Subsequently, tests were performed to estimate the root growth potentials. None of the treatments changed the water parameters or growth potentials of the roots. The inoculations improved the growth and nutrient uptake of the seedlings, although the combination of P. fluorescens CECT 844 and T. melanosporum did not generally lead to a significant improvement over the positive effects of a simple inoculation of T. melanosporum; however, the addition of P. fluorescens CECT 844 did double the rate of the mycorrhization of T. melanosporum. These results may be promising for enhancing the cultivation of truffles.

© iForest -Biogeosciences and Forestry IntroductionIn the first half of the 20 th century, the first Dutch elm disease (DED) pandemic caused a massive loss of elms in Europe and North America. The much more aggressive O. novo-ulmi Brasier took the place of the causal agent, Ophiostoma ulmi (Buisman) Nannf., in the second half of the century. The second pathogen has caused the disappearance of adult elms in many European and North American locations (Brasier & Kirk 2010). O. novo-ulmi is almost impossible to control through chemical, biological or silvicultural methods due to its high virulence and highly effective transmission via small beetles of the Scolytus and Hylorgopinus genera (Webber 2000). Tolerant elm genotype selection and breeding has been the most successful strategy for elm recovery, particularly in urban environments , 2011, Solla et al. 2005a. The Spanish elm breeding and conservation programme began in 1986 as the result of an agreement between the Spanish Environmental Administration and the Technical University of Madrid School of Forestry Engineering. Its two main objectives were to conserve remaining elm genetic resources and to transmit their variability to future generations of tolerant elms obtained through breeding; i.e., hybridisation of selected progenitors (native or tolerant Asian elms) to obtain tolerant trees with the appearance of native elm species.The first elm breeding programme began in the Netherlands in 1928 (Heybroek 1993) and was followed by several programmes in the United States and various European countries Santini et al. 2011, Buiteveld et al. 2014. As a result of crossing these species with native elms, a wide range of hybrid clones of varying tolerance levels and genetic backgrounds is now available on the market. The Spanish programme took advantage of the knowledge, methodologies and plant materials previously developed by the Dutch and Italian programmes. In the first 14 years, U. pumila was used as the main source of resistance, giving rise to 10 crossings tolerant to O. novo-ulmi (Solla et al. 2000). The tolerance of these crossings was tested in clone replicates (N > 16) over several years at various locations, and clone adaptation to different environments in Spain was evaluated. Five crossings with Asian background were recently selected to be released onto the market for ornamental use.In the 1990s the Spanish programme included some native elms, mainly U. minor, in the O. novo-ulmi susceptibility trials. In the following decade the programme focused mainly on selecting native elms. This new strategy complied with European and Spanish legislation governing the quality and genetic background of forest reproductive materials for production and marketing. In the European Union, forest reproductive materials are governed by Council Directive © SISEF http://www.sisef.it/iforest/ 172 iForest (2015) 8: 172-180

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StUMMARYA study was made of the incidence of Neisseria meningitidis and N. lactamica in a school population; 2470 children aged between 5 and 7 years were studied from four schools in Alcala de Henares (Madrid). Nasopharyngeal swabs were taken in June, November and March, between 1979 and In all the surveys except one, the proportion of carriers of N. lactamica was higher than that of N. meningitidis, reaching a ratio of about 2: 1 in the complete study.The predominant serogroup of meningococcus found was B (41 %), with nongroupable strains reaching 430. A study of serotypes within group B showed a predominance of nontypable strains (48-5 %o), while those strains considered to be most virulent (types 2 and 1, 8, 15) reached 40 o.Eighteen per cent of N. lactamica strains were observed to agglutinate with antimeningococcal sera whilst the remainder of the strains were rough. When these strains were studied with the antiscrum-agar technique, using antimeningococcal sera, a high percentage of strains cross-reacted with the meningococci. The susceptibility of strains to sulphadiazine, penicillin, ampicillin, chloramphenicol, rifampicin and spiramycin was determined.Finally an analysis was made of the effect that an elevated colonization rate of N. lactamica might have on colonization by meningococi. The necessity of using fine epidemiological markers in tracing virulent strains in a population at risk is stressed. Selective prophylactic measures are also necessary.

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Dutch elm disease (DED) is a vascular wilt disease caused by the pathogens Ophiostoma ulmi and Ophiostoma novo-ulmi with multiple ecological phases including pathogenic (xylem), saprotrophic (bark) and vector (beetle flight and beetle feeding wound) phases. Due to the two DED pandemics during the twentieth century the use of elms in landscape and forest restoration has declined significantly. However new initiatives for elm breeding and restoration are now underway in Europe and North America. Here we discuss complexities in the DED ‘system’ that can lead to unintended consequences during elm breeding and some of the wider options for obtaining durability or ‘field resistance’ in released material, including (1) the phenotypic plasticity of disease levels in resistant cultivars infected by O. novo-ulmi; (2) shortcomings in test methods when selecting for resistance; (3) the implications of rapid evolutionary changes in current O. novo-ulmi populations for the choice of pathogen inoculum when screening; (4) the possibility of using active resistance to the pathogen in the beetle feeding wound, and low attractiveness of elm cultivars to feeding beetles, in addition to resistance in the xylem; (5) the risk that genes from susceptible and exotic elms be introgressed into resistant cultivars; (6) risks posed by unintentional changes in the host microbiome; and (7) the biosecurity risks posed by resistant elm deployment. In addition, attention needs to be paid to the disease pressures within which resistant elms will be released. In the future, biotechnology may further enhance our understanding of the various resistance processes in elms and our potential to deploy trees with highly durable resistance in elm restoration. Hopefully the different elm resistance processes will prove to be largely under durable, additive, multigenic control. Elm breeding programmes cannot afford to get into the host–pathogen arms races that characterise some agricultural host–pathogen systems.

Dutch elm disease (DED) spread across Europe and North America in the 20th century killing most natural elm populations. Today, breeding programmes aim at identifying, propagating and studying elm clones resistant to DED. Here, we have compared the physiology and biochemistry of six genotypes of Ulmus minor of variable DED resistance. Leaf gas exchange, water potential, stem hydraulic conductivity and biochemical status were studied in 5-year-old trees of AB-AM2.4, M-DV2.3, M-DV2 9 M-CC1.5 and M-DV1 and 6-year-old trees of VA-AP38 and BU-FL7 before and after inoculation with Ophiostoma novo-ulmi. Leaf water potential and net photosynthesis rates declined, while the percentage loss of hydraulic conductivity (PLC) increased after the inoculation in susceptible trees. By the 21st day, leaf predawn and midday water potential, stomatal conductance to water vapour and net photosynthesis rates were lower, and PLC was higher in trees of susceptible (S) genotypes inoculated with the pathogen than in control trees inoculated with water, whereas no significant treatment effect was observed on these variables in the resistant (R) genotypes. Fourier transform infrared spectroscopy analyses revealed a different biochemical profile for branches of R and S clones. R clones showed higher absorption peaks that could be assigned to phenolic compounds, saturated hydrocarbons, cellulose and hemicellulose than S clones. The differences were more marked at the end of the experiment than at the beginning, suggesting that R and S clones responded differently to the inevitable wounding from inoculation and repeated sampling over the experimental course. We hypothesize that a weak activation of the defence system in response to experimental wounding can contribute to the susceptibility of some genotypes to O. novo-ulmi. In turn, the decline in shoot hydraulic conductivity and leaf carbon uptake caused by the infection further exacerbates tree susceptibility to the fungus.