Arbuscular mycorrhizal fungi (AMF) as bioprotector agents against wilt induced by Verticillium spp. in pepper.

Verticillium dahliae Kleb. is a vascular pathogen that alters water status and growth of pepper plants and causes drastic reductions in yield. Its control is difficult because it can survive in field soil for several years. The application of arbuscular mycorrhizal fungi (AMF) as bioprotector agents against V. dahliae is an alternative to the use of chemicals which, in addition, is more respectful with the environment. The establishment of the mutualistic association of plant roots and AMF involves a continuous cellular and molecular dialogue between both symbionts that includes the preactivation of plant defense responses that may enhance the resistance or tolerance of mycorrhizal plants to soil-borne pathogens. Some AMF can improve the resistance of Capsicum annuum L. against V. dahliae. This is especially relevant for pepper cultivars (i.e. cv. Piquillo) that exhibit high susceptibility to this pathogen. Compared with non-mycorrhizal plants, mycorrhizal pepper can exhibit more balanced antioxidant metabolism in leaves along the first month after pathogen inoculation, which may contribute to delay both the development of disease symptoms and the decrease of photosynthesis in Verticillium-inoculated plants with the subsequent benefit for yield. In stems, mycorrhizal pepper show earlier and higher deposition of lignin in xylem vessels than nonmycorrhizal plants, even in absence of the pathogen. Moreover, AMF can induce new isoforms of acidic chitinases and superoxide dismutase in roots. Mycorrhizal-specific induction of these enzymatic activities together with enhanced peroxidase and phenylalanine ammonia-lyase in roots may also be involved in the bioprotection of Verticillium-induced wilt in pepper by AM

Growth, yield and physiology of Verticillium-inoculated pepper plants treated with ATAD and composted sewage sludge

A greenhouse experiment was conducted to investigate the impact of sanitized sewage sludges, ATAD (aerobic thermophilic autothermic digestion) and composted, on Verticillium-induced wilt in pepper plants (Capsicum annuum L. cv. Piquillo). Two doses of ATAD (15 and 30% v/v) and three of composted sludge (15, 30 and 45% v/v) were applied to a peat-based potting mix. Unamended substrate was included as control. Half of the plants were inoculated with V. dahliae, whereas the other half remained non-inoculated. Result showed that ATAD and composted sludge increased growth and yield of non-inoculated plants. V. dahliae reduced net photosynthesis (P n), mainly as a consequence of stomatal closure, 5 weeks after pathogen inoculation. The actual photosystem II efficiency was also reduced and consequently the electron transport rate (ETR). No photoinhibitory damage was observed at this time in diseased plants. At the end of the experiment, diseased plants showed lower plant biomass and fruit yield. ATAD sludge had little effect on the disease. Compost slightly alleviated Verticillium-induced wilt when applied at lower doses (15% v/v), which resulted in increased P n and ETR, and higher plant biomass and fruit yield. By contrast, higher doses of compost (45% v/v) enhanced the effect of the pathogen, which was related to the high substrate salinity in this treatment

Response of mycorrhizal grapevine to Armillaria mellea inoculation: disease development and polyamines.

A study was conducted with the vine rootstock Richter 110 (Vitis berlandieri Planch. x Vitis rupestris L.) in order to assess whether the colonisation by the arbuscular mycorrhizal fungus (AMF) Glomus intraradices (BEG 72) can delay the disease development in plants inoculated with the root-rot fungus Armillaria mellea (Vahl:Fr) Kummer, and to elucidate if the levels of polyamines (PAs) are modified in response to G. intraradices, A. mellea or by the dual infection. Four treatments were considered: control and G. intraradices-inoculated plants infected or not with A. mellea. Plant growth, mycorrhizal colonisation and disease development were monitored throughout the experiment. High performance liquid chromatography (HPLC) in combination with fluorescence spectrophotometry was used to separate and quantify free root and leaf polyamines. The slower development of pathogenic symptoms and the higher plant biomass of mycorrhizal plants inoculated with A. mellea indicate an increase of tolerance due to the AMF inoculation. The variations in free PA levels detected at the beginning of the pathogenic infection suggest that PAs may have a potential role in the signalling mechanisms of the tolerance of mycorrhizal plants against A. mellea

Yield and nutritional value of first-cutting alfalfa grown in temperature gradient greenhouses under future climate change scenarios depend on Sinorhizobium meliloti strain

Ponencia presentada a la 51 Reunión Científica de la SEEP celebrada en la Escuela Superior de Ingenieros Agrónomos de la Universidad Pública de Navarra entre el 14 y el 18 de mayo de 2012.El objetivo del estudio fue analizar bajo distintos escenarios de simulación de cambio climático (CO2 y temperatura elevados), el efecto de tres cepas de Sinorhizobium meliloti, en la producción, calidad y digestibilidad in-vitro de la alfalfa. Las alfalfas más productivas en su primer corte durante el mes de noviembre fueron las inoculadas con la cepa 102F34, seguidas por la 102F78 y la 1032GMI. El CO2 y la temperatura elevados aumentaron el contenido en fibras, disminuyendo la digestibilidad invitro de la materia seca en las plantas inoculadas con las cepas 102F78 y 1032GMI. La proteína bruta, un indicador de la calidad del forraje, descendió en condiciones de CO2 y temperatura elevados, independientemente de la cepa inoculada. Si bien las plantas inoculadas con la cepa 102F78 produjeron forraje con mayor concentración de proteína bruta, la mayor digestibilidad obtenida con la cepa 102F34, hizo que de las tres cepas analizadas, sea ésta la más adecuada en el escenario de cambio climático estudiado.Elevated CO2 may decrease alfalfa forage quality and in-vitro digestibility through a drop in crude protein and an enhancement of fibre content. The aim of the present study was to analyze the effect of elevated CO2, elevated temperature and Sinorhizobium meliloti strains on alfalfa yield, forage quality and in-vitro dry matter digestibility. Shoot dry matter under elevated CO2 and temperature was different depending on the S. meliloti strain, with 102F34 inoculated plants being the most productive, followed by 102F78, and then 1032GMI. Plants inoculated with the 102F34 strain did not enhance neutral or acid detergent fibre under elevated CO2 or temperature and hence, in-vitro dry matter digestibility was unaffected. Crude protein content, an indicator of forage quality, was negatively related to shoot yield. Plants inoculated with 102F78 showed a similar shoot yield to those inoculated with 102F34, but had higher crude protein content at elevated CO2 and temperature. Under these climate change conditions, 102F78 inoculated plants produced more quality forage. However, the higher digestibility of plants inoculated with the 102F34 strain under any CO2 or temperature conditions, makes them more suitable for growing under applied experimental climate change conditions.Ministerio de Ciencia e Innovación (MICINN BFU2008-01405 y BFU2011-26989), Fundación Universitaria de Navarra (PIUNA-2008), Fundación Caja Navarra y Asociación de Amigos de la Universidad de Navarra

Characterization of the adaptive response of grapevine (cv. Tempranillo) to UV-B radiation under water deficit conditions

This work aims to characterize the physiological response of grapevine (Vitis vinifera L.) cv. Tempranillo to UV-B radiation under water deficit conditions. Grapevine fruit-bearing cuttings were exposed to three levels of supplemental biologically effective UV-B radiation (0, 5.98 and 9.66 kJ m−2 day−1) and two water regimes (well watered and water deficit), in a factorial design, from fruit-set to maturity under glasshouse-controlled conditions. UV-B induced a transient decrease in net photosynthesis (Anet), actual and maximum potential efficiency of photosystem II, particularly on well watered plants. Methanol extractable UV-B absorbing compounds (MEUVAC) concentration and superoxide dismutase activity increased with UV-B. Water deficit effected decrease in Anet and stomatal conductance, and did not change non-photochemical quenching and the de-epoxidation state of xanthophylls, dark respiration and photorespiration being alternative ways to dissipate the excess of energy. Little interactive effects between UV-B and drought were detected on photosynthesis performance, where the impact of UV-B was overshadowed by the effects of water deficit. Grape berry ripening was strongly delayed when UV-B and water deficit were applied in combination. In summary, deficit irrigation did not modify the adaptive response of grapevine to UV-B, through the accumulation of MEUVAC. However, combined treatments caused additive effects on berry ripening

Correct and discipline behavior: attitude of the Catholic Church against popular violence (XVI-XVIII centuries)

Durante el Antiguo Régimen asistimos a un interés creciente por parte de las autoridades religiosas por lograr controlar el orden público. Para conseguir este ambicioso objetivo emplearon distintos procedimientos en la búsqueda por lograr adoctrinar y corregir ciertas actitudes. Entre éstos nos encontramos con los manuales de confesores, los sermonarios y las constituciones sinodales. Siendo empleados para la prevención de futuros desórdenes públicos y con la idea de aumentar la seguridad ciudadana.During the Old Regime we attended an increasing interest on the part of the religious authorities to manage to control the public order. In order to secure this ambitious objective they used different procedures in the search to manage to indoctrinate and to correct certain attitudes. Between these we find with manual for confessors, sermons and synodal constitutions. Being used for the prevention of future public disorders and with the idea to increase the citizen security

Carbon balance, partitioning and photosynthetic acclimation in fruit-bearing grapevine (Vitis vinifera L. cv. Tempranillo) grown under simulated climate change (elevated CO2, elevated temperature and moderate drought) scenarios in temperature gradient

Although plant performance under elevated CO2 has been extensively studied in the past little is known about photosynthetic performance changing simultaneously CO2, water availability and temperature conditions. Moreover, despite of its relevancy in crop responsiveness to elevated CO2 conditions, plant level C balance is a topic that, comparatively, has received little attention. In order to test responsiveness of grapevine photosynthetic apparatus to predicted climate change conditions, grapevine (Vitis vinifera L. cv. Tempranillo) fruit-bearing cuttings were exposed to different CO2 (elevated, 700 ppm vs. ambient, ca. 400 ppm), temperature (ambient vs. elevated, ambient +4 °C) and irrigation levels (partial vs. full irrigation). Carbon balance was followed monitoring net photosynthesis (AN, C gain), respiration (RD) and photorespiration (RL) (C losses). Modification of environment 13C isotopic composition (δ13C) under elevated CO2 (from −10.30 to −24.93‰) enabled the further characterization of C partitioning into roots, cuttings, shoots, petioles, leaves, rachides and berries. Irrespective of irrigation level and temperature, exposure to elevated CO2 induced photosynthetic acclimation of plants. C/N imbalance reflected the inability of plants grown at 700 ppm CO2 to develop strong C sinks. Partitioning of labeled C to storage organs (main stem and roots) did not avoid accumulation of labeled photoassimilates in leaves, affecting negatively Rubisco carboxylation activity. The study also revealed that, after 20 days of treatment, no oxidative damage to chlorophylls or carotenoids was observed, suggesting a protective role of CO2 either at current or elevated temperatures against the adverse effect of water stress

Plant physiology and proteomics reveals the leaf response to drought in alfalfa (Medicago sativa L.)

Despite its relevance, protein regulation, metabolic adjustment, and the physiological status of plants under drought is not well understood in relation to the role of nitrogen fixation in nodules. In this study, nodulated alfalfa plants were exposed to drought conditions. The study determined the physiological, metabolic, and proteomic processes involved in photosynthetic inhibition in relation to the decrease in nitrogenase (Nase) activity. The deleterious effect of drought on alfalfa performance was targeted towards photosynthesis and Nase activity. At the leaf level, photosynthetic inhibition was mainly caused by the inhibition of Rubisco. The proteomic profile and physiological measurements revealed that the reduced carboxylation capacity of droughted plants was related to limitations in Rubisco protein content, activation state, and RuBP regeneration. Drought also decreased amino acid content such as asparagine, and glutamic acid, and Rubisco protein content indicating that N availability limitations were caused by Nase activity inhibition. In this context, drought induced the decrease in Rubisco binding protein content at the leaf level and proteases were up-regulated so as to degrade Rubisco protein. This degradation enabled the reallocation of the Rubisco-derived N to the synthesis of amino acids with osmoregulant capacity. Rubisco degradation under drought conditions was induced so as to remobilize Rubisco-derived N to compensate for the decrease in N associated with Nase inhibition. Metabolic analyses showed that droughted plants increased amino acid (proline, a major compound involved in osmotic regulation) and soluble sugar (D-pinitol) levels to contribute towards the decrease in osmotic potential (Ψs). At the nodule level, drought had an inhibitory effect on Nase activity. This decrease in Nase activity was not induced by substrate shortage, as reflected by an increase in total soluble sugars (TSS) in the nodules. Proline accumulation in the nodule could also be associated with an osmoregulatory response to drought and might function as a protective agent against ROS. In droughted nodules, the decrease in N2 fixation was caused by an increase in oxygen resistance that was induced in the nodule. This was a mechanism to avoid oxidative damage associated with reduced respiration activity and the consequent increase in oxygen content. This study highlighted that even though drought had a direct effect on leaves, the deleterious effects of drought on nodules also conditioned leaf responsiveness