O. Santamaría

Fungi associated with the decline of Pinus halepensis in Spain

Fungal species richness and composition within needles and twigs in 55 stands of Pinus halepensis, spread out over the whole Iberian Peninsula, were determined. The aim was to evaluate the relationships of fungal communities with local environmental variables, in order to analyze the potential causes of the current decline of this pine species in Spain. A total of 35 fungal taxa were isolated from 1980 moist chambers analysed (990 per vegetal tissue). A taxon within the Alternaria alternata complex was most frequent, followed by Leptostroma pinastri, Aspergillus niger, Diplodia pinea and Phomopsis sp. At the tree level, tissue was a significant response variable and a higher species richness was found in needles as compared to twigs. On the other hand, the multivariate analysis showed the environmental variables ‘age’, ‘shadow’, ‘elevation’, ‘mean temperature’, ‘illumination’ and ‘availability of water’ significantly influenced fungal species composition. In particular, ‘mean temperature’, was an important variable implicated in the general weakening of this thermophilic pine species, and appeared to be inversely correlated with the occurrence of several conifer pathogens such as Brunchorstia pinea, Cytospora sp., Diplodia pinea, Naemacyclus niveus, Pestalotiopsis stevensonii and Sclerophoma pythiophila. This study shows a possible combined effect of abiotic and biotic stresses in causing the general decline of Allepo pine in Spain.

Agronomic selenium biofortification in Triticum durum under Mediterranean conditions: From grain to cooked pasta

To improve the nutritional value of durum wheat and derived products, two foliar Se fertilisers (sodium selenate and selenite) were tested at four rates (0-10-20-40gha(-1)) in 2010/2011 and 2011/2012 in southwestern Spain. There was a strong and linear relationship between total Se or selenomethionine (Se-Met) accumulation in grain and Se dose for both fertilisers, although selenate was much more efficient. Se-Met was the main Se species (≈90%) of the total Se extracted from all materials. Milling caused a 27% loss of Se due to the removal of Se located in bran and germ. In the pasta making process and the cooking process the loss of Se, mainly as selenite, was about 7%. Durum wheat may be a good candidate to be included in Se biofortification programs under rainfed Mediterranean conditions, as foodstuffs derived from it could efficiently increase the Se content in the human diet.

Selenium Speciation in Malt, Wort, and Beer Made from Selenium-Biofortified Two-Rowed Barley Grain

Selenium (Se) biofortification of barley is a suitable strategy to increase the Se concentration in grain. In the present paper, the suitability of this Se-biofortified grain for making Se-enriched beer is analyzed. The aim of the present study was to evaluate the effect of different Se fertilizer doses (0, 10, and 20 g of Se ha(-1)) and forms (sodium selenate or sodium selenite) on the Se loss during the malting and brewing processes and Se speciation in grain, malt, wort, and beer. Samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC)-ICP-MS for total Se and speciation. Mashing-lautering was the process with the greatest Se loss (83.8%). After malting and brewing, only 7.3% of the initial Se was retained in beer, mainly in selenite form. Even so, the fertilizer application of sodium selenate at 20 g ha(-1) increased the total Se concentration almost 6-fold in the final beer in comparison to the use of grain derived from unfertilized barley. The present paper provides evidence that the use of Se-biofortified barley grain as a raw material to produce Se-enriched beer is possible, and the results are comparable to other methods in terms of efficiency.

Selenium biofortification in bread-making wheat under Mediterranean conditions: influence on grain yield and quality parameters

Abstract. The diet of millions of people around the world is deficient in selenium (Se). Bread-making wheat has been successfully used in Se biofortification programs under temperate climate to remedy Se deficiency. However, its suitability under Mediterranean conditions and its effect on the grain yield and quality parameters are not well known. In a wheat field in south-western Spain, two foliar Se fertilisers (sodium selenate and sodium selenite) were applied at four application rates (0, 10, 20, 40 g ha–1) in 2010–11 and 2011–12. Results showed a strong and linear relationship between total Se in grain and Se dose for both fertilisers, although selenate was much more efficient. A dose of 10 g sodium selenate ha–1 was able to increase significantly the Se in grain to close to the recommended values, although Se loss of 28% during the milling process might be expected. Grain yield was not negatively affected by fertilisation, but grain protein and dry gluten were slightly negatively affected, but only in the dry year. Alveograph parameters were either not affected or slightly favoured by Se fertilisation in any studied year. Bread-making wheat is a good candidate to be included in biofortification programs under semi-arid Mediterranean conditions.

Interaction Between Diplodia pinea and D. scrobiculata in Red and Jack Pine Seedlings

Sphaeropsis sapinea sensu lato is a conifer fungal pathogen that causes shoot blight and stem cankers. Recently, the former S. sapinea has been divided into two species, Diplodia pinea and D. scrobiculata. The aims of the study were to determine the contribution of each species in disease development on red and jack pines by means of co-inoculations and molecular identifications, and to evaluate how the presence of each species affects the development and aggressiveness of the other. Symptom severity (distance below the inoculation site at which necrotic needles were observed) and identification length (the maximum distance from inoculation site from which either D. pinea or D. scrobiculata was identified using molecular methods) were recorded 4 weeks after inoculating wounded seedlings with agar plugs colonized by these pathogens. The results suggested that D. pinea was much more aggressive on both hosts than D. scrobiculata. When a seedling was co-inoculated with these pathogens, the symptom development appeared to be mainly due to D. pinea. The presence of D. pinea also interfered with the establishment of D. scrobiculata in the plant tissue. However, D. scrobiculata showed antagonism toward D. pinea. When both pathogens co-occurred in a single seedling, symptom severity caused by D. pinea was less than when D. pinea alone was present.

Antagonism between Byssochlamys spectabilis (anamorph Paecilomyces variotii) and plant pathogens: Involvement of the bioactive compounds produced by the endophyte

Fungal endophytes can be part of the defensive system of plants against multiple pathogens by competing for resources, hyperparasitism or producing bioactive compounds with antimicrobial properties. There is an ever-increasing interest for obtaining new and environmentally friendly products to use in the fight against pathogens. With this purpose, Byssochlamys spectabilis (anamorph Paecilomyces variotii), which is a fungal species that commonly occurs, was evaluated as an antagonistic organism towards three phytopathogens (Biscogniauxia mediterranea, Fusarium moniliforme and Phytophthora cinnamomi). First, an in vitro experiment was designed to test the effect that the endophyte filtrate had on the three pathogens. The endophyte filtrate decreased the radius growth rate of F. moniliforme by nearly 10%. Consequently, the antagonism between B. spectabilis and F. moniliforme was evaluated in Lolium rigidum plants under greenhouse conditions by means of co-inoculations. The endophyte produced a decrease of 50–75% in the disease severity caused by the pathogen in the earliest infection stages. Crude extracts of B. spectabilis were obtained to determine the secondary metabolites responsible for such an effect. The bioactivity-guided chromatography and HPLC-MS (high performance liquid chromatography coupled with mass spectrometry) of the active fraction suggested that the antibiotic activity was caused by viriditoxin. In conclusion, the fungal endophyte B. spectabilis and/or its bioactive compounds showed antagonism towards several phytopathogens and deserves further study to investigate its actual potential for use as a biocontrol agent.