Maria Helena Almeida

Germination success, survival and seedling vigour of Quercus suber acorns in relation to insect damage

Abstract This study assesses the effects of damage caused by Curculio elephas Gyll. (Coleoptera: Curculionidae) and Cydia splendana Hb. (Lepidoptera: Tortricidae) on mature acorns of cork oak trees, Quercus suber L., in Portugal. The average number of insect-attacked acorns varied between 68, 44 and 17%, in three sites, respectively. Acorns assorted into increasing damage classes had a decreasing acorn dry weight and a faster germination rate. The percentage of germination was very high (>90%) in all classes. Seedlings resulting from more intensely damaged acorns exhibited a slower growth rate and lower dry mass production than seedlings resulting from low damaged acorns.

A comprehensive assessment of the transcriptome of cork oak (Quercus suber) through EST sequencing

BackgroundCork oak (Quercus suber) is one of the rare trees with the ability to produce cork, a material widely used to make wine bottle stoppers, flooring and insulation materials, among many other uses. The molecular mechanisms of cork formation are still poorly understood, in great part due to the difficulty in studying a species with a long life-cycle and for which there is scarce molecular/genomic information. Cork oak forests are of great ecological importance and represent a major economic and social resource in Southern Europe and Northern Africa. However, global warming is threatening the cork oak forests by imposing thermal, hydric and many types of novel biotic stresses. Despite the economic and social value of the Q. suber species, few genomic resources have been developed, useful for biotechnological applications and improved forest management.ResultsWe generated in excess of 7 million sequence reads, by pyrosequencing 21 normalized cDNA libraries derived from multiple Q. suber tissues and organs, developmental stages and physiological conditions. We deployed a stringent sequence processing and assembly pipeline that resulted in the identification of ~159,000 unigenes. These were annotated according to their similarity to known plant genes, to known Interpro domains, GO classes and E.C. numbers. The phylogenetic extent of this ESTs set was investigated, and we found that cork oak revealed a significant new gene space that is not covered by other model species or EST sequencing projects. The raw data, as well as the full annotated assembly, are now available to the community in a dedicated web portal at http://www.corkoakdb.org.ConclusionsThis genomic resource represents the first trancriptome study in a cork producing species. It can be explored to develop new tools and approaches to understand stress responses and developmental processes in forest trees, as well as the molecular cascades underlying cork differentiation and disease response.

Genetic correlations between wood quality traits of Pinus pinaster Ait

Abstract• It is essential to understand how characteristics are related to each other in breeding programmes to select wood properties, in order to avoid that, in selecting for one trait, we are negatively affecting another. Moreover, measuring wood properties is time consuming and expensive.• This study assesses genetic and phenotypic correlations between wood density components and spiral grain of 46 half-sib families of Pinus pinaster in seventeen-year-old trees.• Results showed that genetic correlations for all wood density components were higher than corresponding phenotypic correlations. Furthermore, all wood density components were highly genetically correlated with ring density, and also closely associated among themselves. Results showed a higher genetic correlation of ring density with earlywood density (rg = 0.96) than with latewood density rg = 0.79). A moderate to high positive genetic correlation was found between spiral grain and wood density characteristics (0.29–0.61).• We conclude that ring density (overall wood density) can be improved by increasing either earlywood density, latewood percent, or both of these traits, and spiral grain can be modify in future plantations.Résumé• En amélioration génétique, il est essentiel de connaître le degré de liaison entre caractères de manière à éviter lors de la sélection pour un caractère une contre-sélection pour un autre. De plus, la mesure des propriétés du bois est lourde et coûteuse.• Dans cette étude, nous étudions les corrélations génétiques et phénotypiques entre les composantes de la densité du bois et l’angle du fil chez 46 familles de demi-frères de Pinus pinaster âgées de 17 ans.• Les résultats montrent que les corrélations génétiques pour toutes les composantes de la densité du bois sont plus élevées que les corrélations phénotypiques. De plus, toutes les composantes de la densité sont fortement corrélées génétiquement avec la densité du cerne et étroitement liées entre elles. Les résultats indiquent une liaison génétique plus forte entre la densité du cerne et la densité du bois initial (rg = 0.96) qu’avec le bois final (rg = 0.79). Une corrélation génétique modérée à forte est mise en évidence entre l’angle du fil du bois et les caractéristiques de densité (0.29–0.61).• Nous concluons que la densité du cerne peut être améliorée soit en augmentant la densité du bois initial, soit la proportion de bois final, soit les deux et que l’angle du fil peut être modifié pour les plantations futures.

A liquid chromatography/electrospray ionisation tandem mass spectrometry method for the simultaneous quantification of salicylic, jasmonic and abscisic acids in Coffea arabica leaves.

BACKGROUND Plants have developed an efficient system of recognition that induces a complex network of signalling molecules such as salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA) in case of a pathogenic infection. The use of specific and sensitive methods is mandatory for the analysis of compounds in these complex samples. RESULTS In this study a liquid chromatography/electrospray ionisation tandem mass spectrometry method was developed and validated for the simultaneous quantification of SA, JA and ABA in Coffea arabica (L.) leaves in order to understand the role of these phytohormones in the signalling network involved in the coffee defence response against Hemileia vastatrix. The results showed that the method was specific, linear (r ≥ 0.99) in the range 0.125-1.00 µg mL⁻¹ for JA and ABA and 0.125-5.00 µg mL⁻¹ for SA, and precise (relative standard deviation ≤11%), and the limit of detection (0.010 µg g⁻¹ fresh weight) was adequate for quantifying these phytohormones in this type of matrix. CONCLUSION In comparison with healthy leaves, those infected with H. vastatrix (resistance reaction) displayed an increase in SA level 24 h after inoculation, suggesting the involvement of an SA-dependent pathway in coffee resistance.

Genotype × Environment interactions in Pinus pinaster at age 10 in a multi-environment trial in Portugal: a maximum likelihood approach

Abstract• To study adaptive variation and genotype × environment interactions (GE) of 30 populations from Portugal, Spain, France and Australia, we evaluated total height, diameter, stem form and survival in a multi-environment provenance trial in Portugal, 10 y after plantation, using the restricted maximum likelihood (REML) approach.• Significant differentiation was found among populations and also among seedlots from Portugal, populations from different altitude classes and from different provenance regions. Seed orchards showed significantly better growth and stem form. GE interaction was significant for all traits which indicates the existence of differences on phenotypic plasticity among populations, and displayed a pattern that could be related to general or specific adaptation of populations, and/or to human-mediated germplasm transfer.• Seed orchards, and the Monção and Leiria populations showed generally better growth and stem form, and some high altitude populations ranked higher in growth or survival (Bragança, S.Pedro do Sul, Manteigas-Pma30) at the high-altitude Montalegre site. There was a lack of genetic uniformity among populations of the same provenance region.• Tentative recommendations are made for afforestation, breeding and conservation.

Genetic variation of chemical and mechanical traits of maritime pine (Pinus pinaster Aiton). Correlations with wood density components

Abstract• BackgroundGenetic selection for one trait can have an impact on other important traits for final use; thus, it is important to assess the correlation between traits.• MethodsGenetic control and relationships among lignin content predicted by near infrared spectroscopy, radial modulus of elasticity (MOERad) and the radial modulus of rupture (MORRad), as well as its correlations with wood density components and spiral grain were assessed by estimating heritability, phenotypic and genetic correlations using 552 Pinus pinaster trees from 46 half-sib families.• ResultsThe results of this study showed that lignin amount is under a moderate genetic control (h2 = 0.34) but due to the low coefficient of variation observed, selection for lignin content through breeding could yield modest gains. Selection based on density will result in a decrease of the lignin content, and that the lignin content was more dependent on the proportion of latewood.• ConclusionsThe results show that MOERad and MORRad are under moderate genetic control (h2 = 0.34 and h2 = 0.30 respectively), suggesting possible genetic gains by selection for higher resistance and elasticity. MOERad had higher correlations with latewood than earlywood components. Negative correlations were observed between mechanical traits and lignin content, while the correlations with spiral grain were positive.

Gall induction may benefit host plant: a case of a gall wasp and eucalyptus tree.

Gall-inducing insects display intimate interactions with their host plants, usually described as parasitic relationships; the galls seem to favor the galler alone. We report on a case in which the presence of the galls induced by Leptocybe invasa Fisher & LaSalle (Hymenoptera; Eulophidae) benefit its host plant, the river red gum Eucalyptus camaldulensis Dehnh. Field observations showed that E. camaldulensis plants infected by this gall wasp were less susceptible to cold injury than neighboring conspecific plants without galls. In the laboratory, frost resistance was compared between galled and non-galled plants which were both divided into two subgroups: cold-acclimated plants and plants that were non-acclimated. Galled plants displayed higher frost resistance than the non-galled ones, and the differences were higher in non-acclimated plants compared with acclimated ones. Physiological changes in host plant were determined by chemical analyses of chlorophylls, proteins, soluble sugars and anthocyanin contents. The results showed higher values of all physiological parameters in the galled plants, supporting the hypothesis that the presence of the gall wasp induces physiological changes on the plant foliage, which may in turn increase plant defense mechanisms against cold. Therefore, the toll of galling by the herbivore may pay off by the host plant acquiring increased frost resistance. This work provides evidence for physiological changes induced by a herbivore which might have a positive indirect effect on the host plant, promoting frost resistance such as cold acclimation.