Postherpetic neuralgia is an exceptionally drug-resistant neuropathic pain. To investigate the pathophysiological mechanisms underlying postherpetic neuralgia we clinically investigated sensory disturbances, pains and itching, with an 11-point numerical rating scale in 41 patients with ophthalmic postherpetic neuralgia. In all the patients we recorded the blink reflex, mediated by non-nociceptive myelinated Abeta-fibers, and trigeminal laser evoked potentials (LEPs) related to nociceptive myelinated Adelta- and unmyelinated C-fiber activation. We also sought possible correlations between clinical sensory disturbances and neurophysiological data. Neurophysiological testing yielded significantly abnormal responses on the affected side compared with the normal side (P<0.001). The blink reflex delay correlated with the intensity of paroxysmal pain, whereas the Adelta- and C-LEP amplitude reduction correlated with the intensity of constant pain (P<0.01). Allodynia correlated with none of the neurophysiological data. Our study shows that postherpetic neuralgia impairs all sensory fiber groups. The neurophysiological-clinical correlations suggest that constant pain arises from a marked loss of nociceptive afferents, whereas paroxysmal pain is related to Abeta-fiber demyelination. These findings might be useful for a better understanding of pain mechanisms in postherpetic neuralgia.

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.

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Mycorrhizae have been key living microorganisms in the plant colonization of terrestrial environments. The crucial roles of mycorrhizae are to provide plant nutrition and stress resistance for plant growth and development. Potassium (K + ) shows important functions in different metabolic processes and physiological functions and is the third crucial component of most crop fertilizers (after nitrogen and phosphorus). This chapter discusses the current state of knowledge about the role of mycorrhizal symbiosis in the release, solubilization, and transport of potassium from the soil to plants. Improved metagenomic analyses and the availability of transcriptome data provide promising tools for studying fungal weathering and the mycorrhizal contributions to K + solubilization and K + transport to plants. Additionally, some benefits of mycorrhizal potassium uptake in plants are described.

© iForest -Biogeosciences and Forestry IntroductionWater and nutrient availability are the main constraints on plant productivity in semi-arid Mediterranean ecosystems. The preservation of mycoflora diversity depends on the status of plant roots (Marulanda et al. 2006). Forest species in these areas often develop specific strategies to improve their water usage in response to drought (Martínez-Ferri et al. 2000).Several studies have been conducted to improve the quality of seedlings produced in nurseries (Caravaca et al. 2005). Several authors reported that soil amendment with ectomycorrhizal fungi and plant-growth-promoting rhizobacteria (PGPR) increased plant survival and seedling quality, especially in soils with low microbial activity (Chanway 1997, Probanza et al. 2001.Pseudomonas fluorescens generally shows several characteristics of an effective PGPR. It is easily cultivated in vitro, and it colonizes a wide range of ecological niches, including plant rhizospheres (Bolton et al. 1993). Additionally, P. fluorescens genomes are highly diverse, which most likely increases the P. fluorescens survival (Silby et al. 2009). The ecological flexibility of such bacteria allows them to exploit a wide variety of nutrients to adapt to environmental changes for survival. P. fluorescens also improves plant growth by producing phytohormones such as auxins (e.g., IAA -Karabaghli et al. 1998). It also has a high capacity for phosphorus solubilization and can produce siderophores (Matthijs et al. 2007). Despite the very well-known positive effects of P. fluorescens on plant survival, only a few studies have been conducted to study its influence on the growth of forest species (Rincón et al. 2008, Ouahmane et al. 2009). We recently demonstrated that the inoculation of Aleppo pine (Pinus halepensis Mill.) with P. fluorescens CECT 844 improved the vegetative growth and N absorption of the P. halepensis seedlings (Dominguez et al. 2012).The use of environmental-friendly natural microbial inocula, such as PGPR or mycorrhizal fungi, is presented in this study as a potential alternative fertilizers. These microorganisms are also beneficial for the maintenance of pre-existing soil microflora, thus contributing to the conservation of soil biodiversity. The amended soil in the nursey increases the vegetative vigor and morphophysiological quality of forest species growth for reforestation purposes (Chanway 1997).Information regarding the productivity of ectomycorrhizal fungi, their ecological functions and their contributions to the productivity and recovery of altered agroecosystems is increasingly valuable in agroforestry. In Spain, the black truffle (Tuber melanosporum Vitt.) is of substantial economic and social value in rural areas of the Mediterranean (Reyna 2007), although studies on the contributions of T. melanosporum to the growth and physiology of forest plants are scarce (Domínguez-Nuñez 2002). Moreover, the ecological value of such symbiosis in the recovery of Mediterranean ecosystems has not been well characterized.The...