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The massive mortality of Castanea sativa in southwestern Europe, which was caused by different species of Phytophthora spp., led to the introduction of seeds of the Asiatic species Castanea crenata and Castanea mollissima and to hybridization to breed for resistance to Phytophthora spp. In Spain, two programmes were developed: one programme, focussed mainly on obtaining first generation hybrids by controlled pollinations, and the other programme, based on selection among open-pollinated progenies collected from first and second generation hybrids, in both cases between sweet and Japanese chestnut. A clone collection of 194 of the clones obtained is conserved at the Lourizán Forest Reseach Centre, and 32 of these were approved as basic material for forest reproduction. A sample of 356 individuals was genotyped using 13 isozyme loci, including the clone collection and several stands of Asiatic species. Only three loci were identified as being diagnostic among these species. The diversity of stands of both Asiatic species was reduced compared to that of C. sativa. Genotype inspection of diagnostic loci and two Bayesian procedures (STRUCTURE and NEWHYBRIDS) were used to classify all individuals into genealogical classes and, thus, reconstruct the history of chestnut hybridization in Spain. Source


de la Mata R.,Research Center Forestal Of Lourizan | Zas R.,Mision Biologica de Galicia
European Journal of Forest Research | Year: 2010

The inland region of Galicia (NW Spain) marks the boundary between the Atlantic climate of the coastal area and the typical Mediterranean climate of central Spain. Compared to the Atlantic coast, climate in this area has a pronounced summer drought, lower annual precipitation, and higher annual thermal oscillation. Despite the high productivity and ecological importance of maritime pine in inland Galicia, local forest reproductive material (FRM) of high genetic quality is not available for this area. Seed sources originating elsewhere and of unknown adaptation to this area are commonly used for reforestation. With the aim of finding new sources of FRM for this region and exploiting the genetic gains of existing breeding programmes, we analysed the performance in field conditions of improved families of the Coastal Galicia (CG) and Western Australia (WA) breeding programmes. Growth, stem characteristics and branch habit were evaluated in five progeny trials established following a coastal-to-inland gradient. Likelihood-based analyses were used to estimate genetic correlations between environments and to test statistically for causes and patterns of genotype × environment interaction. Because of the strong non-random spatial structures and heterogeneity of residual variances, the analyses were carried out using heterogeneous residual variance mixed models on spatially adjusted data. The results indicated that there is not sufficient evidence to subdivide Galicia into the two current deployment areas. Interaction patterns do not reveal significant differences between zones, and crossover interactions for height growth are present both between and within areas. On the inland sites, the Atlantic improved materials clearly outperformed unimproved seedlots tested in adjacent provenance trials, suggesting the feasibility of using both the CG and WA breeding materials as sources of FRM for reforestation in inland Galicia. Of the two, the WA material showed excellent results for all traits. The inclusion of this material into the Galician maritime pine breeding population should be strongly considered. © 2010 Springer-Verlag. Source


Pestana M.,Research Center Forestal Of Lourizan | Santolamazza-Carbone S.,Research Center Forestal Of Lourizan
Agricultural and Forest Entomology | Year: 2010

1 Ecological interactions between banded pine weevil Pissodes castaneus and blue-stain fungus Leptographium serpens, when simultaneously sharing the same host plant (maritime pine Pinus pinaster) in winter and spring, were investigated. Temporal components of the interaction were taken into account by either introducing the weevils and the pathogen simultaneously or sequentially, with the weevils being introduced 1 month after the fungal inoculation. 2 We measured larval mortality, development time, offspring number, sex ratio and body size of P. castaneus. Phloem phosphorus and nitrogen concentrations were also assessed. Furthermore, we tested whether: (i) emerging offspring transported propagules of the fungus; (ii) artificially-contaminated weevils may transmit the disease to healthy trees; and (iii) field collected P. castaneus carry the fungus. 3 The fungus enhanced weevil colonization and brood production in both seasons. During winter and spring, adults from trees where the pathogen was inoculated prior to weevil introduction emerged earlier than weevils from trees where they had been introduced simultaneously with the fungus. During winter, weevils from pre-inoculated trees were also larger. Sex ratio and larval mortality were not affected. Leptographium serpens did not affect phloem nitrogen content but phosphorus content was greater in plants inoculated with the pathogen, which may explain the findings on weevil growth. 4 Sixty-five percent of the weevils that emerged from inoculated trees carried spores of L. serpens, although no successful isolation was made from field collected weevils. The fungus was recovered from 25% of the trees infested with artificially-contaminated weevils. 5 These results suggest that P. castaneus benefits from the presence of L. serpens and may contribute to its spread. © 2010 The Authors. Agricultural and Forest Entomology © 2010 The Royal Entomological Society. Source


Miguez-Soto B.,Research Center Forestal Of Lourizan | Fernandez-Lopez J.,Research Center Forestal Of Lourizan
Tree Genetics and Genomes | Year: 2012

Total height, diameter, index volume, stem straightness, apical dominance, and survival were assessed at 8 years from seed in an open-pollinated progeny test of 36 families of European chestnut (Castanea sativa Miller) established at two sites in the Atlantic area of Galicia, Spain. Iterative spatial analysis was applied to eliminate the effect of the spatial dependence in the original data and to estimate accurately genetic parameters for evaluating the potential for selection of the measured trees. Spatial analysis was very beneficial for growth traits and survival, but less so if at all for form traits. Estimated individual heritabilities ranged from moderate to high for growth traits (ĥ 2 i = 0.29 - 0.42%) and stem straightness (ĥ 2 i = 0.24 - 0.42%) High coefficients of additive genetic variance were obtained for volume (ĈV A = 36.5 - 41.5%) and straightness(ĈV A = 44.26 - 53.84%) Phenotypic and estimated genetic correlations between growth traits were very high, and correlations between sites indicated that there was no important family × site interaction. No adverse correlations between traits were evident. The results indicate the ample potential for selection in the current progeny trial, where responses to within-family and combined selection for growth traits may be high. Accordingly, three selection scenarios were addressed with the aim to initiate the selection of individuals for implementing the Forest Breeding Plan of Galicia for European chestnut. © 2011 Springer-Verlag. Source


Moreira X.,University of California at Irvine | Mooney K.A.,University of California at Irvine | Zas R.,Mision Biologica de Galicia MBG CSIC | Sampedro L.,Research Center Forestal Of Lourizan
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

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. Source

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