Virus-vector nematodes in cereals and fruit crops in Spain

8 páginas, tabla estadistica y mapasStudies on nepoviruses and tobraviruses, and their relationships with their associated vector nematodes, are scarce in Spain. However, virus disease symptoms have often been detected and their nematode vectors are widespread in Peninsular Spain. Nepovirus vector nematodes (Longidorus attenuatus, L. coespiticola, L. elongatus, L. macrosoma, Xiphinema coxi, X. diversicaudatum, X. index, X. italiae, X. pseudocoxi and X. vuittenezi) have been found associated with fruit and cereal crops. AH are also widespread in other crops and uncultivated areas, together with X. rivesi, which has not yet been found associated with fruit and cereal crops in Spain. Tobravirus vectors have been less studied in Spain. Ofthe five recorded species, Paratrichodorus minor and Trichodorus primitivus are present on maize and wheat respectively. The geographical and host distribution ofthese nematodes are given and their ecological characteristics are discussed.Peer reviewe

Paralongidorus iberis sp.n. and P. monegrensis sp.n. from Spain with a polytomous key to the species of the genus Paralongidorus Siddiqi, Hooper & Khan, 1963 (Nematoda : Longidoridae)

14 páginas, 3 figuras y 2 tablas estadísticasSpecies of the genus Paralongidorus were found for the fírst time in Spain near Serreta Negra (Huesca), in the North-West of the country. Two new species, P. iberis sp.n. and P. monegrensis sp. n., are described. P. iberis sp. n. is characterized by its médium size (4.4-4.9 mm), rounded set off lip región, stirrup-shaped amphidial pouch and conical dorsally convex tail with conical terminus. It is close to P. lemoni from which it differs in tail shape, presence of males, body length, position of guiding ring, and a and c ratios. P. monegrensis sp. n. is characterized by its large body size (7.5-12 mm), hemispherical expanded lip región, stirrup-shaped amphidial pouch, and conical dorsally convex tail with rounded terminus. It resembles P. sandellus and P. xiphinemoides. It differs from P. sandellus by its longer body and odontostyle and anterior position of guiding ring, and from P. xiphinemoides by presence of males, odontostyle length, position of guiding ring, and c' ratio. A polytomous key of the 70 species described in the genus is proposed and two new combinations are proposed, P. sativus (Soni & Nama, 1983) n. comb. and P. wiesae (Heyns, 1994) n. comb.Peer reviewe

Study of the distribution of genus Xyphinema Cobb, 1913 (Nematoda: Dorylaimida) in relation with some edaphic factors in the Central Region (Spain)

11 Pag., 4 Tabl.[EN] The influence of texture, pH, percentage of organic matter and soil type on genus Xiphinema distribution on the low basin of Alberche river has been done, studying 275 soil samples from different vegetation, soil and climate. The Xiphinema species found were in order of frequency the following ones: X. pachtaicum (38,8%), X. diversicaudatum (6,2%), X. italiae (2,2%), X. coxi and X. sahelense (0,7%), X. brevicolle, X. index and X. turcicum (0,4%). The statistical analysis of X. pachtaicum and X. diversicaudatum in relation with the edaphic factors has been done, because they are the most frequent species appeared. Clay percentage and pH have influence on distribution and abundance of X. diversicaudatum and organic matter in both species. The edaphic characteristics of samples in which the other Xiphinema species were found are indicated. Finally, the interest of knowing restrictive factors in these species distribution is pointed out for the eight found species, four are known as virus transmitters.[ES] Se estudia la influencia de la textura, pH, porcentaje de materia orgánica y tipo de suelo sobre la distribución de las especies del género Xiphinema en la cuenca baja del rio Alberche (Región Central); mediante el estudio de 275 muestras de suelo tomadas en áreas con diferente vegetación, suelo y clima. Se han encontrado en orden de frecuencia, las siguientes especies: X. pachtaicum (38,8%), X. diversicaudatum (6,2%), x: italiae (2,2%), X. coxi y X. sahelense (0,7%) y X. brevicolle, X. index y X. turcicum (0,4%). Se hace un análisis estadístico de X. pachtaicum y X. diversicaudatum, por ser las especies más frecuentes, encontrándose que la materia orgánica influye sobre las dos especies y la arcilla y el pH lo hacen sobre la presencia y abundancia de X. diversicaudatum. Se indican además las características de las muestras donde aparecen las restantes especies. Por último, se señala la importancia que, desde el puntó de vista agrobiológico, tiene el conocimiento de los factores limitantes para estos nematodos, puesto que de las ocho especies encontradas cuatro han sido confirmadas como transmisoras de virus.Peer reviewe

In vitro decay of Aextoxicon punctatum and Fagus sylvatica woods by white and brown-rot fungi

12 pages, 5 figures, 1 table, 34 references.The in vitro decay of Aextoxicon punctatum and Fagus sylvatica wood by the fungi Trametes versicolor, Ganoderma australe, Phlebia chrysocrea and Lentinus cyathiformis was studied by the agar-block method, and then the decayed woods were analyzed by chemical and spectroscopic techniques. The results demonstrated the strong resistance of the A. punctatum wood to the brown-rot fungus L. cyathiformis; the resistance might be related to the low S/G lignin ratio in this Austral hardwood. Wood decay by the Austral white-rot fungi G. australe and P. chrysocrea was rather limited, and preferential degradation of lignin was not produced although all the fungi studied increased wood digestibility. The most characteristic white and brown-rot decay patterns were observed during the in vitro decay with T. versicolor and L. cyathiformis, respectively. Trametes versicolor caused high weight losses and reduced the lignin content of the wood, whereas L. cyathiformis produced a preferential removal of xylan. No important changes in the solid-state 13C NMR spectra were observed after wood degradation by T. versicolor, but this technique evidenced an increase in aromatic carbon by L. cyathiformis. This increase was higher than that found in the Klason lignin content, suggesting the presence of altered lignin fractions in the brown-rotted wood.Peer Reviewe

The white-rot fungus Pleurotus ostreatus secretes laccase isozymes with different substrate specificities

8 p.-2 tab.-5 fig.Four laccase isozymes (LCC1, LCC2, LCC3 and LCC4) synthesized by Pleurotus ostreatus strain V-184 were purified and characterized. LCC1 and LCC2 have molecular masses of about 60 and 65 kDa and exhibited the same pI value (3.0). Their N termini were sequenced, revealing the same amino acid sequence and homology with laccases from other microorganisms. Laccases LCC3 and LCC4 were characterized by SDS-PAGE, estimating their molecular masses around 80 and 82 kDa, respectively. By native isoelectrofocusing, their pI values were 4.7 and 4.5, respectively. When staining with ABTS and guaiacol in native polyacrilamide gels, different specificities were observed for LCC1/LCC2 and LCC3/ LCC4 isozymes.Peer Reviewe

Appraisal of biogeochemical markers for the assessment of damage levels in soils affected by wild fires

Comunicación oral SSS22-1TU3O-005 presentada en la sesión Oral Programme - SSS22 Wildfire effects on soil organic carbon dynamics, soil degradation and soil redistribution (co-listed in BG & ERE).-- Congreso, celebrado del 2-7 de abril de 2006, en Viena, Austria.Forest fires, a frequent and recurrent severe perturbation in Mediterranean ecosystems, exert both immediate and lasting ecological and environmental impacts in part caused by depth transformation on soil physical and chemical characteristics as well as on qualitative and quantitative changes in the organic matter (OM) composition, properties and dynamics which are reflected in the structure of the whole trophic system especially on microbial populations.Peer reviewe

Biogeochemical parameters surrogated to the recovery of soils after forest fire events

2 pages, 7 references. Comunicación oral 074 presentada en el citado congreso, celebrado del 9-14 de septiembre 2007, en Torquay, Reino Unido.Forest fires are considered as the main disturbance in the Mediterranean basin (Naveh, 1990) and exerts both immediate and lasting ecological and environmental impacts. This is in part caused by a depth transformation of soil physical, chemical and biological characteristics associated to qualitative and quantitative changes in the organic matter (OM) (González-Pérez et al., 2004) which is reflected in the structure of the whole system including microbial populations (Pastor and Post, 1986; Pietikäinen et al., 2000). This negatively affects soil health and quality favouring the occurrence of erosive processes and the lost of a non- renewable natural resource such is soil.Peer reviewe

Relaciones entre comunidades de nematodos y pastos terofíticos en suelos ácidos de la Región Central

11 páginas y tablas estadísticasEn este trabajo se estudian las relaciones entre las comunidades de pastos y nematodos en áreas marginales de producción de cereales ubicadas en vastas «mesas» llamadas rañas del norte de Guadalajara. El muestreo se llevó a cabo en cada una de las rañas, realizándose 80 inventarios de pasto para los que se utilizó un cuadrado de 1 x 1 m, tomándose en el mismo una muestra de suelo para el estudio de nematodos. Con los datos de cobertura de las especies vegetales y la densidad de los grupos taxonómicos de los nematodos se realizó una clasificación de muestras y especies (TWINSPAN) que nos separó las muestra en cinco grupos y nos puso de manifiesto relaciones entre especies pascícolas y nematodos en estos hábitats. Esto permitió asociar especies de pasto y nematodos y profundizar en la ecología de estas últimas que fundamentalmente habían sido estudiadas en cultivos intensivos de importancia económica.Peer reviewe

Laccase SilA from Streptomyces ipomoeae CECT 3341, a key enzyme for the degradation of lignin from agricultural residues?

15 páginas.-- 4 referencias.-- 37 referenciasThe role of laccase SilA produced by Streptomyces ipomoeae CECT 3341 in lignocellulose degradation was investigated. A comparison of the properties and activities of a laccase-negative mutant strain (SilA-) with that of the wild-type was studied in terms of their ability to degrade lignin from grass lignocellulose. The yields of solubilized lignin (acid precipitable polymeric lignin, APPL) obtained from wheat straw by both strains in Solid State Fermentation (SSF) conditions demonstrated the importance of SilA laccase in lignin degradation with the wild-type showing 5-fold more APPL produced compared with the mutant strain (SilA-). Analytical pyrolysis and FT-IR (Fourier Transform Infrared Spectroscopy) confirmed that the APPL obtained from the substrate fermented by wild-type strain was dominated by lignin derived methoxyphenols whereas those from SilA- and control APPLs were composed mainly of polysaccharides. This is the first report highlighting the role of this laccase in lignin degradation. © 2017 Blánquez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This study was funded in part by projects CTQ2014-56038-C3-2-R and CGL2016-78937-R (INTERCARBON) from the Spanish Ministry for Economy and Competitiveness. N.T Jiménez Morillo acknowledges a FPI research grant (BES-2013-062573) and A. Blánquez is awarded with a grant from the project CTQ2014-56038-C3-2-R.Peer reviewe

La salud del suelo—un nuevo reto para microbiólogos y químicos

[EN]: Soil health refers to the biological, chemical, and physical features of soil that are essential to long-term, sustainable agricultural productivity with minimal environmental impact. Thus, soil health provides an overall picture of soil functionality. Although it cannot be measured directly, soil health can be inferred by measuring specific soil properties (e.g. organic matter content) and by observing soil status (e.g. fertility). There is also increased interest in studying soil microorganisms in their particular environments, as microbial diversity is intimately related to soil structure and function. One of the key objectives in determining soil health is to acquire indicators that can be used to evaluate the soil’s current status and hence to develop sustainable agricultural systems. In this regard, significant progress has been made over the last few years in the development of specific biomarkers and macromolecular probes, enabling rapid and reliable measurements of soil microbial communities. In addition, modern molecular biological techniques, such as fluorescence in situ hybridization (FISH), reverse transcriptase polymerase chain reaction (RT-PCR), denaturing gradient gel electrophoresis (DGGE), and terminal restriction fragment length polymorphism (T-RFLP), have facilitated the analysis of microbial biodiversity and activity, whereas the application of modern analytical techniques, such as nuclear magnetic resonance (NMR) and pyrolysisgas chromatography-mass spectrometry (Py-GC-MS), have provided data on soil chemistry. The combination of these two approaches offers promise in determining soil health status.[ES]: El concepto de salud del suelo se relaciona con las características biológicas, químicas y físicas que son esenciales para una productividad agrícola sostenible a largo plazo con un mínimo impacto ambiental. La salud del suelo es el más fiel reflejo de su funcionalidad. Aunque no puede medirse directamente, se puede inferir a partir de la determinación de propiedades específicas del mismo suelo (p.e. el contenido en materia orgánica) y por la observación de su estado (p.e. la fertilidad). El interés por el estudio de los microorganismos del suelo en su propio medio está aumentando, puesto que la diversidad microbiana está estrechamente relacionada con la estructura y función del suelo. Un objetivo clave para determinar la salud de un suelo es la disponibilidad de indicadores factibles de ser utilizados en la evaluación de su estado y, a partir de aquí, implementar sistemas de agricultura sostenible. El desarrollo de biomarcadores específicos y sondas macromoleculares ha evolucionado considerablemente en los últimos años, lo cual ha permitido obtener medidas fiables y rápidas de las comunidades microbianas del suelo. Por otro lado, las modernas técnicas biomoleculares más recientes (p.e. la hibridación in situ mediante fluorescencia [FISH], la reacción en cadena de la polimerasa mediante transcriptasa inversa [RT-PCR], la electroforesis en gel con gradiente desnaturalizante [DGGE] y el análisis del polimorfismo en la longitud de los fragmentos de restricción terminales [T-RFLP]) permiten analizar la biodiversidad y actividad microbianas, mientras que la aplicación de técnicas analíticas modernas (p.e. resonancia magnética nuclear [NMR], pirólisis-cromatografía de gases-espectrometría de masas [Py-GC-MS]) proporciona datos sobre la química del suelo. La combinación de estas dos aproximaciones metodológicas ofrece buenas perspectivas en la determinación del estado de salud del suelo.Peer reviewe