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Background and Aims: The dependence of oak decline on climatic stressors is fairly well documented, but little is known about the impact of soil properties on growth plasticity and as predisposing factors to decline. Here we investigate if oak dieback and individual responses to climatic stresses are related to soil nutrient availability. Methods: Chemical properties of surrounding soil and tree-ring series of healthy, declining, and dead oaks were analysed in four replicated forest stands under Atlantic wet climate conditions in NW Spain, where massive death has occurred. Results: Current nutrient availability significantly predicted oak death risk. Lower concentrations of macronutrients (N, Ca, Mg, and Na) were found in soil surrounding dead trees than living trees. Water excess before the growing season negatively affected growth, and trees showing declining symptoms were more responsive to climate. Trees with greater Ca availability in the surrounding soil were able to respond more plastically to the stress caused by water excess, while trees with lower Ca levels were less responsive to the stress and more predisposed to die. Conclusion: This work revealed that both climatically-induced dieback and the individual dendroclimatic response of oaks may be linked to the uneven distribution of soil resources in declining Atlantic forests. © 2013 Springer Science+Business Media Dordrecht.

Although maternal environmental effects are increasingly recognized as an important source of phenotypic variation with relevant impacts in evolutionary processes, their relevance in long-lived plants such as pine trees is largely unknown. Here, we used a powerful sample size and a strong quantitative genetic approach to analyse the sources of variation of early seedling performance and to identify seed mass (SM)-dependent and -independent maternal environmental effects in Maritime pine. We measured SM of 8924 individual seeds collected from 10 genotypes clonally replicated in two environments of contrasting quality (favourable and stressful), and we measured seedling growth rate and biomass allocation to roots and shoots. SM was extremely variable (up to 14-fold) and strongly determined by the maternal environment and the genotype of the mother tree. The favourable maternal environment led to larger cones, larger seeds and reduced SM variability. The maternal environment also determined the offspring phenotype, with seedlings coming from the favourable environment being 35% larger and with greater root/shoot ratio. Transgenerational plasticity appears, thus, to be a relevant source of phenotypic variation in the early performance of this pine species. Seed provisioning explained most of the effect of the maternal environment on seedling total biomass. Environmental maternal effects on seedling biomass allocation were, however, determined through SM-independent mechanisms, suggesting that other epigenetic regulation channels may be involved. © 2013 Macmillan Publishers Limited All rights reserved.

Optimizing the germination timing is crucial for the establishment of new generations. We hypothesized that environmental maternal effects may be relevant in the fine tuning of this trait in a long-lived Mediterranean model tree. We analyzed the influence of maternal genotype, maternal environment and their interaction on the germination success and germination phenology of 8725 Pinus pinaster seeds collected from genotypes clonally replicated in two contrasting environments. Besides maternal genetic effects, the maternal environment significantly affected both the percentage and the timing of germination. Seeds from the more favourable environment germinated 7.5 days earlier and showed higher germination rate (0.93. ±. 0.01 vs 0.85. ±. 0.03). Seed weight significantly influenced germination time, but seed weight differences between maternal environments were not enough to explain this form of transgenerational plasticity. The effect of the maternal environment varied depending on the genotype, indicating that genetic variation in the sensitivity to the maternal environment in this pine species does exist. © 2011 Elsevier B.V.

The resistance to abiotic stress is increasingly recognised as being impacted by maternal effects, given that environmental conditions experienced by parent (mother) trees affect stress tolerance in offspring. We hypothesised that abiotic environmental maternal effects may also mediate the resistance of trees to biotic stress. The influence of maternal environment and maternal genotype and the interaction of these two factors on early resistance of Pinus pinaster half-sibs to the Fusarium circinatum pathogen was studied using 10 mother genotypes clonally replicated in two contrasting environments. Necrosis length of infected seedlings was 16% shorter in seedlings grown from favourable maternal environment seeds than in seedlings grown from unfavourable maternal environment seeds. Damage caused by F. circinatum was mediated by maternal environment and maternal genotype, but not by seed mass. Mechanisms unrelated to seed provisioning, perhaps of epigenetic nature, were probably involved in the transgenerational plasticity of P. pinaster, mediating its resistance to biotic stress. Our findings suggest that the transgenerational resistance of pines due to an abiotic stress may interact with the defensive response of pines to a biotic stress.

The apparent failure of invasions by alien pines in Europe has been explained by the co-occurrence of native pine congeners supporting herbivores that might easily recognize the new plants as hosts. Previous studies have reported that exotic pines show reduced tolerance and capacity to induce resistance to those native herbivores. We hypothesize that limited genetic variation in resistance to native herbivores and the existence of evolutionary trade-offs between growth and resistance could represent additional potential constraints on the evolution of invasiveness of exotic pines outside their natural range. In this paper, we examined genetic variation for constitutive and induced chemical defences (measured as non-volatile resin in the stem and total phenolics in the needles) and resistance to two major native generalist herbivores of pines in cafeteria bioassays (the phloem-feeder Hylobius abietis and the defoliator Thaumetopoea pityocampa) using half-sib families drawn from a sample of the population of Pinus radiata introduced to Spain in the mid-19th century. We found (i) significant genetic variation, with moderate-to-high narrow-sense heritabilities for both the production of constitutive non-volatile resin and induced total phenolics, and for constitutive resistance against T. pityocampa in bioassays, (ii) no evolutionary trade-offs between plant resistance and growth traits or between the production of different quantitative chemical defences and (iii) a positive genetic correlation between constitutive resistance to the two studied herbivores. Overall, results of our study indicate that the exotic pine P. radiata has limited genetic constraints on the evolution of resistance against herbivores in its introduced range, suggesting that, at least in terms of interactions with these enemies, this pine species has potential to become invasive in the future. © 2013 Macmillan Publishers Limited All rights reserved 0018-067X/13.

[EN] Most plants deliver continuously complex admixtures of volatile organic compounds (VOCs) to the surrounding atmosphere that may change in response to biotic aggressions. Recent papers have shown that those induced VOC’s could serve for within-plant signalling of distant tissues, also for attracting herbivore predators and parasitoids, but also may be perceived by other plants in the neighbourhood as danger signals activating their defensive system. Little is know about these defensive abilities in Maritime Pine (P. pinaster) and Radiata Pine (P. radiata), two pine species with major relevance for forestry in northern Spain. Here we studied the ability of pine saplings of those species (‘receptor’ plants) growing during 40 days in experimental greenhouses for perceiving the herbivory suffered by neighbour plants (‘emitters’) by the large pine weevil (Hylobius abietis), and for changing their defensive phenotypes accordingly. In particular, we quantified the content on non-volatile resin and total polyphenolics in the needles and in the upper and lower part of the stems of receptor plants just after the growing period (constitutive) and after being exposed by herbivory by the weevil for 5 days (induced defences). Constitutive defences in the stem showed a marked within-plant distribution pattern, with more resin in the upper part a more polyphenolics in the lower part of the stem in both pine species. We found a significant 66% increase in the constitutive concentration of non-volatile resin in the upper part of P. radiata saplings grown in presence of herbivory in their neighbourhood. However we did not found changes in polyphenolics or other tissues in P. radiata neither in P. pinaster. Plants growing in the neighbourhood of attacked plants showed significant or marginally significant induced susceptibility responses when exposed to real herbivory, with lower levels of chemical defences than naive plants. Taken together, our results suggest that young pine tree, [ES] Las plantas liberan continuamente complejas mezclas volátiles al aire y la composición de estas emisiones puede variar dependiendo de si la planta fue atacada y de la naturaleza específica del atacante. Estudios recientes demostraron que los compuestos orgánicos volátiles (VOCs) emitidos tras episodios de herbivoría pueden ser utilizados por las plantas para transmitir información a tejidos distantes, pueden ser percibidos por antagonistas de los herbívoros, y mismo pueden ser percibidos por las plantas vecinas indicándoles la existencia de riesgo, desencadenando cambios antes de un posible ataque y aumentando su resistencia en consecuencia. Tanto el pino del país (P. pinaster) como el pino insigne (P. radiata) son dos especies que adquirieron una gran importancia económica en el sector forestal gallego en los últimos tiempos por lo que, la comprensión de su comportamiento defensivo frente a agresiones biológicas, en particular en la edad juvenil, puede ser de utilidad para reducir las pérdidas económicas debidas a la herbivoría en estos géneros. En el presente trabajo de investigación se estudió si plántulas de P. pinaster y P. radiata (receptoras) pueden modificar sus características defensivas cuando crecen en la vecindad de plantas atacadas por el coleóptero Hylobius abietis (emisoras). En particular, cuantificamos el contenido de resina no volátil y polifenoles totales en el tallo superior, inferior y acículas en las dos especies. En las plantas emisoras se observó un incremento significativo de las defensas químicas en P. pinaster, pero no en P. radiata. La herbivoría en plantas vecinas tuvo como consecuencia un incremento significativo de un 66% en la concentración constitutiva de resina en la parte superior del tallo de P. radiata en relación a plantas que crecieron sin herbivoría en la vecindad. Sin embargo no se observó efecto en otros tejidos, en el contenido de polifenoles totales, ni en P. pinaster. Las plantas que crecieron en presencia de vecinas, [GL] As plantas liberan continuamente complexas mesturas volátiles ó aire e a composición destas emisións pode variar dependendo de si a planta foi atacada e da natureza específica do atacante. Estudos recentes demostraron que os compostos orgánicos volátiles (VOCs) emitidos tras episodios de herbivoría poden ser empregados polas plantas para transmitir información á tecidos distantes, poden ser percibidos por antagonistas dos herbívoros, e mesmo poden ser percibidos polas plantas veciñas indicándolles a existencia de risco, desencadeando cambios antes de un posible ataque e aumentando a súa resistencia en consecuencia. Tanto o piñeiro do país (P. pinaster) como o piñeiro insigne (P. radiata) son dúas especies que adquiriron unha gran importancia económica no sector forestal galego nos últimos tempos polo que, a comprensión do seu comportamento defensivo fronte a agresións biolóxicas, en particular na idade xuvenil, pode ser de utilidade para reducir as perdas económicas debidas á herbivoría nestes xéneros. No presente traballo de investigación estudouse se plántulas de P. pinaster e P. radiata (receptoras) poden modificar as súas características defensivas cando crecen na veciñanza de plantas atacadas polo gurgullo Hylobius abietis (emisoras). En particular, cuantificamos o contido de resina non volátil e polifenois totais no talo superior, inferior e acículas nas dúas especies. Nas plantas emisoras observouse un incremento significativo das defensas químicas en P. pinaster, pero non en P. radiata. A herbivoría en plantas veciñas tivo como consecuencia un incremento significativo dun 66% na concentración constitutiva de resina na parte superior do talo de P. radiata en relación a plantas que creceron sen herbivoría na veciñanza. Sen embargo non se observou efecto noutros tecidos, no contido de polifenois totais, nin en P. pinaster. As plantas que creceron en presenza de veciñas atacadas por H. abietis mostraron respostas significativas ou marxinalmente significativ

There is increasing evidence that plants can react to biotic aggressions with highly specific responses. However, few studies have attempted to jointly investigate whether the induction of plant defences is specific to a targeted plant tissue, plant species, herbivore identity, and defensive trait. Here we studied those factors contributing to the specificity of induced defensive responses in two economically impor- tant pine species against two chewing insect pest herbivores. Juvenile trees of Pinus pinaster andP. radiata were exposed to herbivory by two major pest threats, the large pine weevil Hylobius abietis (a bark-fee- der) and the pine processionary caterpillar Thaumetopoea pityocampa (a folivore). We quantified in two tissues (stem and needles) the constitutive (control plants) and herbivore-induced concentrations of total polyphenolics, volatile and non-volatile resin, as well as the profile of mono- and sesquiterpenes. Stem chewing by the pine weevil increased concentrations of non-volatile resin, volatile monoterpenes, and (marginally) polyphenolics in stem tissues. Weevil feeding also increased the concentration of non-vol- atile resin and decreased polyphenolics in the needle tissues. Folivory by the caterpillar had no major effects on needle defensive chemistry, but a strong increase in the concentration of polyphenolics in the stem. Interestingly, we found similar patterns for all these above-reported effects in both pine spe- cies. These results offer convincing evidence that induced defences are highly specific and may vary depending on the targeted plant tissue, the insect herbivore causing the damage and the considered defensive compound.

While plant diversity is well known to increase primary productivity, whether these bottom-up effects are enhanced by reciprocal top-down effects from the third trophic level is unknown. We studied whether pine tree species diversity, aphid-tending ants and their interaction determined plant performance and arthropod community structure. Plant diversity had a positive effect on aphids, but only in the presence of mutualistic ants, leading to a threefold greater number of both groups in the tri-specific cultures than in monocultures. Plant diversity increased ant abundance not only by increasing aphid number, but also by increasing ant recruitment per aphid. The positive effect of diversity on ants in turn cascaded down to increase plant performance; diversity increased plant growth (but not biomass), and this effect was stronger in the presence of ants. Consequently, bottom-up effects of diversity within the same genus and guild of plants, and top-down effects from the third trophic level (predatory ants), interactively increased plant performance. © 2012 The Royal Society.

Optimal defense theory (ODT) predicts that the within-plant quantitative allocation of defenses is not random, but driven by the potential relative contribution of particular plant tissues to overall fitness. These predictions have been poorly tested on long-lived woody plants. We explored the allocation of constitutive and methyl-jasmonate (MJ) inducible chemical defenses in six half-sib families of Pinus radiata juveniles. Specifically, we studied the quantitative allocation of resin and polyphenolics (the two major secondary chemicals in pine trees) to tissues with contrasting fitness value (stem phloem, stem xylem and needles) across three parts of the plants (basal, middle and apical upper part), using nitrogen concentration as a proxy of tissue value. Concentration of nitrogen in the phloem, xylem and needles was found to be greater higher up the plant. As predicted by the ODT, the same pattern was found for the concentration of non-volatile resin in the stem. However, in leaf tissues the concentrations of both resin and total phenolics were greater towards the base of the plant. Two weeks after MJ application, the concentrations of nitrogen in the phloem, resin in the stem and total phenolics in the needles increased by roughly 25% compared with the control plants, inducibility was similar across all plant parts, and families differed in the inducibility of resin compounds in the stem. In contrast, no significant changes were observed either for phenolics in the stems, or for resin in the needles after MJ application. Concentration of resin in the phloem was double that in the xylem and MJ-inducible, with inducibility being greater towards the base of the stem. In contrast, resin in the xylem was not MJ-inducible and increased in concentration higher up the plant. The pattern of inducibility by MJ-signaling in juvenile P. radiata is tissue, chemical-defense and plant-part specific, and is genetically variable. © 2012 Moreira et al.

Results of a greenhouse Armillaria ostoyae inoculation experiment, designed for screening resistant Pinus pinaster genotypes and for exploring the role of different phenotypic traits in seedling susceptibility, are reported. The experiment included 39 open-pollinated pine families that comprised a random subset of the breeding population of P. pinaster in Galicia (NW Spain). We employed a non-parametric survival-time analysis to analyze patterns of survival times during 14 months after inoculation with a local A. ostoyae strain. Results indicate (i) a significant correlation between seed weight and tree susceptibility, with seedlings originating from large seeds being more susceptible, (ii) a positive family mean correlation between secondary root weight and size and median life expectancy, and (iii) genetic variation of tree tolerance to A. ostoyae, with some families surviving significantly longer than others. Less susceptible families could be used in breeding programmes or directly in forest plantations to reduce the losses caused by A. ostoyae. Large within-family variation in tolerance to the disease was also observed, suggesting that non additive genetic variance was also important. Although being infected, 32 out of the 1200 inoculated trees survived the fungus infection. These tolerant genotypes comprise an attractive collection to further investigate genetic, phenotypic and environmental factors affecting pine susceptibility to Armillaria root rot.

A doença da murchidão do pinheiro é uma doença grave que afecta florestas de coníferas com uma elevada taxa de mortalidade. É causada pelo nemátode Bursaphelenchus xylophilus, conhecido como nemátode da madeira do pinheiro (NMP). Este organismo é originário da América do Norte, onde não está associado a uma elevada prevalência da doença. O NMP foi introduzido no Japão no início do século XX, propagando-se depois para a China, Ilha Formosa e Coreia, e demonstrou ser devastador para as espécies de coníferas autóctones do Extremo Oriente. Em 1999 o NMP foi detectado na Europa, em Portugal, mas apesar dos esforços para conter a doença, esta disseminou-se por todo o território de Portugal continental e, em 2008, registou-se um caso da doença em Espanha. Dado a introdução recente desta peste na Europa, é da mais alta importância identificar quais as espécies florestais autóctones de maior susceptibilidade e quais as tolerantes/resistentes. Tal informação é importante para o planeamento/gestão das florestas, e também para o estudo da doença, sugerindo mecanismos de susceptibilidade/resistência. Neste trabalho optimizou-se um teste de susceptibilidade para utilização num grande número de amostras. O teste baseia-se na capacidade de nemátodes virulentos atravessarem secções de 5 cm de ramos jovens, com cerca de 2 cm de diâmetro. O processo de optimização passou pela forja de recipientes de dimensões adequadas, criação de um modo de sustentar os ramos em posição vertical, optimização do volume de água onde a base do ramo fica mergulhada e criação de um modo de evitar a desidratação do topo do ramo após inoculação. O crescimento dos nemátodes em laboratório também passou por um scale-up para obtenção de nemátodes em grande quantidade, passando do crescimento em tubos de ensaio para sacos. O teste foi optimizado usando ramos de Pinus pinaster, mas pode ser adaptado a outras espécies.

Que la incidencia de plagas y enfermedades en las masas forestales está en aumento y previsiblemente continuará aumentando es un hecho bien constatado que preocupa enormemente y mantiene en alerta a las autoridades forestales de todo el planeta. Prevenir y proteger nuestras masas forestales se ha convertido en una prioridad silvícola en la gestión de masas naturales y plantaciones forestales. Pero las herramientas profilácticas que dispone el selvicultor son limitadas y están fuertemente restringidas por las exigencias que imponen la gestión forestal sostenible y la certificación forestal. Así, el uso masivo de productos fitosanitarios para reducir la incidencia de plagas y enfermedades en masas forestales es una alternativa en declive que tiende o tenderá a desaparecer.

Experimental induction of plant chemical defences with methyl jasmonate (MeJa) is a valuable tool for understanding the ecology of plant defensive responses. However, few studies have examined whether MeJa-induced defences in conifers are effective against insect herbivores. We studied, in 17 half-sib Pinus pinaster families, (i) the effect of MeJa application on plant growth and on the induction of diterpenoid resin in different sections of the stem; (ii) whether MeJa-induced defences increase the resistance of living pine juveniles against the large pine weevil Hylobius abietis in an in vivo bioassay and (iii) the induction of resin content after weevil wounding. Resin concentration was greater in the upper section of the stem compared with basal sections in both MeJa-induced and non-induced seedlings. Sixty days after MeJa application, treated plants showed 40% greater resin content all along the stem, but reduced height growth compared to control plants. MeJa-induction was effective against the pine weevil, as induced seedlings were 21% less damaged than control plants. Wounding activity by H. abietis produced a strong local defensive response after 48 h, where resin concentration was double that observed in the basal and apical sections not exposed to the insects.

The feasibility of incorporating vermicompost as a plant growth promoter into pine (Pinus pinaster Ait.) nurseries was investigated. Pines were grown in conventional peat-based nursery potting media where the peat was substituted by 0%, 2.5%, 5%, 10% and 25% solid vermicompost. In addition, in order distinguish between possible physical and biochemical mechanisms, the effects of solid vermicompost and vermicompost extracts on pine seedling growth were compared. Five different open-pollinated pine progenies were used in order to evaluate the possible genotype-dependent effects of vermicompost. All pots were provided with adequate mineral fertilization in order to avoid nutrient limitations and arranged in the greenhouse following a bifactorial randomized block design. Twenty weeks after sowing, seedlings were harvested and their aerial and root growth were measured, as well as biomass partitioning and seedling maturity. Amendment with solid vermicompost at 2.5% and 10% significantly stimulated pine seedling height, but not aerial biomass. Vermicompost also produced seedlings with greater shoot:root biomass ratios than the control. Besides, we noticed a significant inhibition of aerial and root biomass with the higher dose of solid vermicompost (25% substrate substitution). No effects, either positive or negative, were detected in plant growth due to the vermicompost extracts. All the reported results were the same for all the different progenies assayed, and therefore no genotype dependent effects were detected.

[EN] Phenotypes are commonly assumed to be the result of the genotype and the environment. However, today we know that parents can also transmit further characteristics to their progeny apart of the conventional genetic heredity. Maternal environment has been shown to have large influences in the phenotype of the progeny. These effects, called maternal effects, are assumed to be adaptive as they may result in increased fitness of the progeny in the environement where it will develop. The best known maternal effects are those related to the environemental effect on the seed weight (SW) and the effect of seed size on seedling development. In the present work we analized the SW of open-pollinated seeds collected from the same genotypes established in two seed orchards (SO) with contrasting environmental conditions, one with especially favourable conditions for pine growth, and the other with important resource limitations and environmental stresses. Results indicated that the maternal environment was the main source of variation of the SW, with seeds from the high quality SO being up to 40% bigger. The maternal environment together with the maternal genotype explained up to 75% of the SW variation. The maternal environmet not only affected the SW, but also have large influence in seedling performance. Seedlings coming from seeds of the high quality SO germinated better and earlier, and were significantly bigger. The results indicated, thus, that environmental maternal effects are very relevant in P. pinaster. These maternal effects are transmitted partially through the SW, but other epigenetic effects not related to the SW appeared to be also involved. These results have important applications in tree breeding programas, and they can be useful for improving early selection procederes, improving the plant quality of seedlings derived from SO, and even improving the efficiency of the selection processes in the progeny trials., [ES] Hoy se sabe que el fenotipo de un individuo non solo se debe a su genotipo y al ambiente en el que se crió. Los progenitores son capaces de transmitir información a su descendencia más allá de los mecanismos genéticos heredados convencionalmente. Así se tiene demostrado ampliamente que el ambiente en el que se desarrolla la madre puede tener una gran influencia sobre el fenotipo de la progenie. Estos efectos, conocidos como efectos maternos, se asumen como un mecanismo más de adaptación al medio ya que suelen favorecer la aparición en la descendencia de individuos fenotípicamente más adaptados al ambiente en el que se van desenvolver. Uno de los efectos maternos ambientales más frecuentemente descritos es el asociado con la influencia ambiental en el peso de la semilla (seed weight, SW), y el efecto de este en el desarrollo posterior de la planta. En el presente trabajo estudiamos las fuentes de variación del SW de Pinus pinaster, buscando cuantificar el papel del ambiente y del genotipo materno en este, y cómo estos factores pueden modular el fenotipo de la progenie. Para ello analizamos las semillas procedentes de los mismos genotipos representados en dos huertos semilleros (HS) clonales con ambientes contrastados, uno con muy buena calidad de estación y otro con condiciones especialmente críticas para el desarrollo de los pinos. Los resultados indican que el ambiente materno fue el condicionante más importante del SW en P. pinaster con semillas hasta un 40% mayores en el HS de mejor calidad. O ambiente y el genotipo materno explicaron en conjunto más del 75% de la variación en el SW. El ambiente materno no sólo influyó al SW sino también afectó de forma contundente a todas as características evaluadas en la progenie. Así, las plántulas procedentes de semillas recogidas en el HS de mejor calidad germinaron más, lo hicieron antes y alcanzaron un mayor tamaño. Los resultados indican, por lo tanto, una gran influencia de los efectos maternos ambientales en P. pi, [GL] Hoxe sábese que o fenotipo de un individuo non só se debe ó seu xenotipo e o ambiente no que se criou. Os proxenitores son capaces de transmitir información á súa descendencia máis aló dos mecanismos xenéticos herdados convencionalmente. Así tense demostrado amplamente que o ambiente no que se desenrola a nai pode ter unha gran influencia sobre o fenotipo da proxenie. Estes efectos, coñecidos como efectos maternos, asúmense como un mecanismo mais de adaptación o medio xa que soe favorecer a aparición na descendencia de individuos fenotipicamente máis adaptados ao ambiente no que se van desenvolver. Un dos efectos maternos ambientais máis frecuentemente descritos é o asociado ca influencia ambiental no peso da semente (seed weight, SW), e o efecto deste no desenrolo posterior da planta. No presente traballo estudamos as fontes de variación do SW de Pinus pinaster, buscando cuantificar o papel do ambiente e do xenotipo materno neste, e cómo estes factores poden modular o fenotipo da proxenie. Para elo analizamos as sementes procedentes dos mesmos xenotipos representados en dous hortos sementeiros (HS) clonais con ambientes contrastados, un con moi boa calidade de estación e outro con condicións especialmente críticas para o desenvolvemento dos piñeiros. Os resultados indican que o ambiente materno foi o condicionante máis importante do SW en P. pinaster con sementes ata un 40% maiores no HS de mellor calidade. O ambiente e o xenotipo materno explicaron en conxunto máis do 75% da variación no SW. O ambiente materno non só influíu ó SW senón tamén afectou de forma contundente a todas as características avaliadas na proxenie. Así, as plántulas procedentes de sementes recollidas no HS de mellor calidade xerminaron máis, o fixeron antes e acadaron un maior tamaño. Os resultados indican, polo tanto, unha gran influencia dos efectos maternos ambientais en P. pinaster, efectos que transmítense tanto a través do SW como a través de outras canles epixenéticas non relaciona

[EN]: Maritime pine (Pinus pinaster) is a species of vital importance to the economy and ecology of Mediterranean and Atlantic forests. In the last decades, several breeding programs for maritime pine in Iberian Peninsula were started looking forward to improve growth, stem form and branching characteristics. Previous field studies in progeny x fertilization trials of the Galician breeding program reported an important genetic variation in the resistance to the phloem-feeder Hylobius abietis which causes large juvenile mortality in several conifer species in Europe. Moreover, this insect fairly preferred fertilized pines, especially with calcium phosphate, regarding unfertilized plants. These results gave us the opportunity to test how fertilization with phosphorus (P, the limiting nutrient in Galician forest soils) and genotype affect the constitutive and induced mechanisms of defence, and fitness costs associated to their production. According to several ecological theories, increases in resource availability for plants could decrease the resource allocation to defences, but no information is available about the relative contribution of constitutive and induced defences to the overall resistance of juvenile pine trees., [ES]: El pino marítimo (Pinus pinaster) es una especie de gran importancia económica y ecológica en el área circumediterranea, donde existen en la actualidad diversos programas de mejora genética de esta especie. Es una especie de crecimiento rápido en la que la etapa juvenil constituye una fase esencial para el éxito de establecimiento. En estudios previos de campo en parcelas del plan de mejora de P. pinaster en Galicia se ha observado variación genética en la resistencia a Hylobius abietis, un curculiónido que causa extensas mortalidades en juveniles de ésta y otras especies de coníferas de toda Europa. Además, se observó que este insecto prefirió claramente a las plantas fertilizadas, especialmente con fósforo (P). Estos resultados abrieron la puerta al estudio de los patrones de influencia de la disponibilidad de P, principal nutriente limitante en el área de estudio, sobre las estrategias defensivas constitutivas e inducidas, y sus costes asociados, dentro de la población Galicia costa. Tal y como proponen diversas teorías ecológicas, un incremento en la disponibilidad de recursos para la planta podría llevar asociado una disminución en la inversión en defensas, pero no se sabe cual sería la contribución relativa de defensas constitutivas e inducidas a la resistencia global.

We investigated the effect of vermicompost on the germination and early development of six different progenies of the maritime pine (Pinus pinaster Ait.). We compared the effects of incorporating solid vermicompost into the potting media to those of vermicompost water extract to asses the extent of not physically-mediated positive effects. The incorporation of vermicompost in the growing media of maritime pine increased germination by 16%, and particularly, addition of vermicompost water extract produced the best results. Plants germinated with vermicompost showed higher N content as compared to control plants, and this could have determined the faster maturation of the treated seedlings. Since the best effects on pine germination were observed after application of vermicompost water extract, other mechanisms, rather than the physical amelioration of the substrate, such as the presence of water soluble nutrients and organic compounds (i.e. humic acids and plant growth regulating substances) in the vermicompost, might be involved in the promotion of germination. Variation in the response of the different pine progenies to vermicompost application was observed thereby confirming the necessity of taking into account genetic variability in order to study the potential of vermicompost and other biologically-active organic materials as a potting amendments.

Hylobius abietis is an important pest of coniferous plantations in Europe, to which high mortality, stem deformities, and growth loss are typically attributed. In pine trees, as in other long-lived organisms, there is uncertainty regarding the long-term costs of short-term resistance against invading organisms. We examined the nutritional status of Pinus pinaster after a 2-year long H. abietis attack, measuring needle and phloem N and P concentrations, and the impact of the damage on subsequent growth, survival, and stem deformities over a period of 5 years. The study sites were a P. pinaster family × fertilization trial, and a neighbouring twin trial with similar climate and soil characteristics that was not attacked. Growth losses after the H. abietis attack were important (up to 40%), but restricted to the first years after the attack. Five years after the attack, the annual height increment of pines in the attacked stand was not related to the initial damage suffered, and plants showed regular stems, normal leader dominance, and regular height after 5 years. These findings suggest strong compensatory growth in P. pinaster and indicate relatively high tolerance to the large pine weevil. Needle nutrient concentrations in the healthy stand were, as expected, significantly greater in experimentally fertilized plants, and they were linearly related to those in phloem showing equilibrated stoichiometry both for nitrogen (r = 0.86; P < 0.01; N = 25) and phosphorus (r = 0.84; P < 0.01; N = 25). However, at the attacked stand, nutrient concentrations in the needles did not follow the experimentally manipulated nutrient availability in soils, and phosphorus concentration in the needles was unexpectedly not related to those in the phloem. The pine seedlings attacked by H. abietis showed altered potential of allocating nutrients to their tissues according to the nutrient availability existing in the soil, as well as altered stoichiometry in N and P concentrations among phlo

Methyl jasmonate (MeJa) is a plant chemical elicitor which has been used to artificially induce chemical defensive responses and resistance against herbivores in many plant species in recent decades. In this paper, we studied the effect of exogenous MeJa application at different concentrations (0, 5, 50, and 100 mM) on growth, chemical defenses and resistance against the large pine weevil Hylobius abietis L in one year old Pinus pinaster Ait. seedlings. We also investigated whether the local application of MeJa on a basal branch would distally elicit defensive responses or growth reductions on the opposite branch and on the upper main stem. Exogenous application of MeJa induced resin accumulation in the stems, and enhanced resistance against H. abietis. The resin content in plants treated with 100 mM was nearly two-fold greater, and the pine weevil consumed 80% less phloem than in control plants. However, concentration of total phenolics in needles was lower in plants treated with the higher MeJa dose, probably because of a local toxic effect. We did not detect any effect of MeJa application on plant growth traits. In addition, the application of MeJa on the experimental branches did not significantly affect the resin content, nor growth rates of the opposite untreated control branches. However, the application of MeJa on the experimental branches significantly increased the resin content in the stem and total phenolics in the needles in the apical stem section of the seedling. These results suggest that the systemic effect of the MeJa induction is restricted to the most valuable parts of the seedlings, and should be considered in further studies aimed to understand the systemic resistance of conifers.

The low nutrient availability of the acidic and sandy soils of Galicia (Northwest Spain) is probably the main environmental factor limiting forest primary productivity in the area. These particular edaphic conditions could have imposed selective pressures on maritime pine populations leading to specific local adaptations. We first assessed the nutritional status of 22 young contemporary Pinus pinaster plantations in Northwest Spain, and then analysed the response to fertilization in three family × fertilization trials, and how this response varied across sites and genotypes. Growth of P. pinaster in Northwest Spain appeared to be largely limited by nutrient availability, where most of the plantations showed severe nutrient deficiencies, especially in P and Mg. According to these deficiencies, a strong positive response to nutrient additions was observed in the three trials, with height increments of up to 30% compared with the unfertilized control. However, the response to fertilizers was very variable from site to site, and in some cases did not agree with the foliar nutritional diagnosis. The response to fertilization was also significantly affected by pine genotype, suggesting that the plastic response to nutrient additions within each environment was under genetic control. However, the family response to nutrient availability was not consistent across sites, and no significant differences among families were observed for the RDPI plasticity index – a single index that summarizes the phenotypic change in multiple environments – when analysed across environments. The strong environmental component modulating phenotypic responses to fertilization could impose an important obstacle to evolve specific adaptations to the local edaphic conditions, as well as to artificially select genotypes adapted to different environments and silviculture regimes.

The effects of establishment fertilization and pine genotype on pine weevil (Hylobius abietis L.) damage was studied in a radiata pine (Pinus radiata D. Don) naturally infected family × fertilization genetic trial in Galicia (northwestern Spain). Fertilization strongly increased both growth and H. abietis damage, especially when calcium phosphate was included in the fertilization treatment. Fertilized plants showed higher degree of debarking, greater leader loss, and higher mortality than unfertilized controls. Because of the greater leader loss, fertilization did not significantly increase the actual height (height of live stem) 1 year after planting. In contrast, after the second growing season, fertilized plants overcompensated for the weevil damage and reached greater height than the unfertilized controls. However, considering the effects on survival and the stem deformities resulting from the leader losses, fertilization should be avoided (or delayed) in P. radiata plantations on clear-cut coniferous areas if the risk of H. abietis is high. Our results also indicate a strong genetic variation in H. abietis susceptibility within the Galician P. radiata breeding population. The high family-mean and the moderate individual-tree heritability estimates suggest that improving resistance to this pest by conventional breeding techniques is possible. The use of planting stock with improved resistance should be considered as another prophylactic measure to supplement the traditional methods employed against this pest.

Changes in resource availability and biotic and abiotic stress may alter the defensive mechanisms of pine trees. The effect of fertilisation on the resin canal structure of Pinus pinaster seedlings established in two trials in NW Spain, one attacked by Hylobius abietis and the other non-attacked, was studied. The leaders of 50 plants were destructively sampled and the resin canal density, the canal area and its relative conductive area in the phloem and xylem were assessed. Experimentally increased nutrient availability significantly decreased resin canal density in the phloem of the seedlings in the two analysed trials, where unfertilised seedlings presented up to 30% more resin canal density than the fertilised seedlings (mean value ± SEM = 0.32 ± 0.02 resin canals mm−2 in the fertilised plants versus 0.45 ± 0.04 resin canals mm−2 in the control plants). Fertilisation had no effect on the resin canal system in the xylem, but significantly increased tracheid size. Significant differences of resin canals among sites were observed mainly in the xylem; the resin canal density was 1.7-fold greater in the attacked site than in the non-attacked site. The similar structure of phloem resin canals in both sites supports that phloem resin canals are constitutive mechanisms of defence in P. pinaster, whereas xylem resin canals would be constitutive mechanisms but also inducible mechanisms of resistance following the attack of pine weevils or bark beetles.

Armillaria ostoyae is an important disease of Pinus pinaster in north-west Spain, which kills trees following a heterogeneous spatial structure. In a progeny trial of P. pinaster seedlings, spatial heterogeneity and autocorrelation of neighbour mortality caused by A. ostoyae impeded proper analysis of the disease incidence. We used variography and kriging methods to describe the spatial distribution of the infection probability and the genetic variation of the resistance to A. ostoyae among families. The spatial structure of disease incidence was modelled, and the probability of survival was corrected by kriging at each tree location. Cumulative mortality 3 years after planting was 65.1 per cent. Significant differences among P. pinaster families in terms of mortality to A. ostoyae were found, with low individual (hi2 = 0.08) and moderate family (hf2 = 0.35) heritability estimates. According to a theoretical semivariogram, the patch size of the disease incidence was ∼63 m wide. This is the first time variography and kriging are used to select P. pinaster resistant to Armillaria root rot. It is concluded that geostatistics provides forest pathologists with a powerful tool for screening resistant trees in field conditions.

[EN] Damage by the pine weevil Hylobius abietis L. (Coleoptera: Curculionidae) on Pinus pinaster Ait. was evaluated in a fertilization × progeny test in Galicia (NW Spain) to determine the genetic variation among families and the possibility to include the resistance to this insect as a selection criteria in the Galician maritime pine breeding program. Several damage and symptoms traits were evaluated. All these traits showed highly significant family effects and were strongly correlated among each other. Individual and family heritability estimates of the wound evaluations in the seedling stems were around 0.2 and 0.8, respectively. Strong genetic correlations among wounds and the average seedling color indicated that this last simple and subjective trait can be used for screening for pine weevil susceptibility. A positive genetic correlation was also observed between diameter growth and pine weevil damage. Faster growing families were more attacked hindering the possibility to include the susceptibility to the insect in the breeding program., [FR] Les dommages provoqués par Hylobius abietis L. (Coleoptera : Curculionidae) au pin maritime (Pinus pinaster Ait.) ont été évalués sur un test génétique de descendances maternelles soumis à différents traitements de fertilisation en Galice (NO Espagne). Le but était d'étudier la variation entre familles du niveau d'attaque de l'insecte et la possibilité d'inclure ce caractère dans le programme d'amélioration du pin maritime en Galice. Différents dégâts et symptômes ont été mesurés ainsi que la hauteur et le diamètre. Tous les traits évalués ont montré un effet famille très significatif et ils ont souvent corrélés entre eux. Les blessures évaluées au niveau de la tige du jeune plant montrent une héritabilité individuelle et familiale d'environ 0,2 et 0,8 respectivement. Le nombre de blessures sur la tige et la couleur des jeunes plants sont corrélés génétiquement. Il semble donc possible d'utiliser cette mesure de coloration, simple et subjective, pour évaluer la sensibilité du pin à l'hylobe. Nous avons aussi observé une corrélation génétique positive entre la croissance en diamètre et les dommages dus à H. abietis. Les familles les plus vigoureuses ont été les plus attaquées, ce qui limite les possibilités d'inclure la sensibilité à l'insecte dans le programme d'amélioration du pin maritime.