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Plants generate energy flows through natural food webs, driven by competition for resources among organisms, which are part of a complex network of multitrophic interactions. Here, we demonstrate that the interaction between tomato plants and a phytophagous insect is driven by a hidden interplay between their respective microbiotas. Tomato plants colonized by the soil fungus Trichoderma afroharzianum, a beneficial microorganism widely used in agriculture as a biocontrol agent, negatively affects the development and survival of the lepidopteran pest Spodoptera littoralis by altering the larval gut microbiota and its nutritional support to the host. Indeed, experiments aimed to restore the functional microbial community in the gut allow a complete rescue. Our results shed light on a novel role played by a soil microorganism in the modulation of plant–insect interaction, setting the stage for a more comprehensive analysis of the impact that biocontrol agents may have on ecological sustainability of agricultural systems. [ABSTRACT FROM AUTHOR]

Estimation of the genetic relatedness of traditional olive cultivars with genetic markers and phenotypic data enables progress in plant breeding, management of genetic resources, and protection of both breeders' rights and certified premium products. We used amplified fragment length polymorphisms (AFLLs), simple sequence repeats (SSRs), and quantitative and qualitative morphological traits, including characteristics recommended for variety registration, to study genetic diversity and relationships in the olive at different levels. The 14 varieties analyzed, which are used for the production of Protected Denomination of Origin extra-virgin olive oil, represent the most important cultivars in the Campania region of Italy and typify a regional diversity characteristic of traditional olive cultivation. The genetic distances obtained with the two DNA marker systems were significantly correlated, as were those obtained by quantitative and qualitative traits. A lower but significant correlation was also observed between distances based on molecular markers and quantitative traits, but qualitative traits, even if sampled in high numbers, failed to describe the pattern of molecular similarity. Our data imply that the type and the number of phenotypic traits scored can greatly influence the outcome of the analysis, and care should be taken when qualitative and quantitative data are combined. Furthermore, the data indicate that the two molecular marker systems are useful for investigating genetic relationships, but they may also be used to complement and assist the traditional registration of varieties. We propose that since the information provided by molecular and morphological marker systems in olive is different, they should serve different purposes. Key words: genetic distances, AFLP, SSR, morphological traits, cluster analysis, germplasm. La mesure de la parente genetique entre cultivars traditionnels de l'olivier a l'aide de marqueurs moleculaires et de donnees phenotypiques rend possible des progres en amelioraCion genetique, en gestion des resources genetiques et en matiere de protection des droits d'obtenteur ou des products certifies a valeur ajoutee. Les auteurs ont employe le polymorphisme de longueur des fragments amplifies (AFLP), les microsatellites (SSR), ainsi que des caracteres morphologiques quantitatifs et qualitatifs, incluant des caracteres recommandes pour l'enregistrement des varietes, pour etudier les relations et la diversite genetiques a divers niveaux chez l'olivier. Les 14 varietes analysees, toutes employees en production d'huile d'olive vierge d'appellation d'origine protegee, representent les plus importants cultivars de la Campanie en Italie et sont typiques de la diversite regionale en production traditionnelle. Les distances genetiques obtenues au moyen des deux types de marqueurs etaient tout aussi significativement correlees que celles obtenues avec les caracteres qualitatifs et quantitatifs. Une correlation plus faible mais significative a egalement ete observee entre caracteres quantitatifs et moleculaires, tandis que les caracteres qualitatifs, meme si plus nombreux, n'ont pas permis de decrire les relations de similarity obtenues avec les donnees moleculaires. Ces donnees impliquemt que le type et le nombre de caracteres phenotypiques examines peuvent grandement influencer le resultat de l'analyse et qu'il faudrait en tenir compte lorsque des donnees qualitatives et quantitatives sont combinees. De plus, les donnees indiquemt que les deux types de marqueurs moleculaires sont utiles pour etudier les relations genetiques, et pour complementer et aider lors du processus traditionnel d'enregistrement des varietes. Les auteurs avancent que, puisque les marqueurs moleculaires et morphologiques different dans l'information qu'ils procuremt chez l'olivier, on devrait les employer pour des fins differentes. Mots-cles: distances genetiques, AFLP, SSR, caracteres morphologiques, analyse de groupement, germoplasme. [Traduit par la Redaction], Introduction The olive (Olea europea L.) is characterized by wide genetic differentiation and a long history of cultivation, as it was one of the first species to be domesticated around [...]

Abstract Background Olive (Olea europaea L.) fruits contain numerous secondary metabolites, primarily phenolics, terpenes and sterols, some of which are particularly interesting for their nutraceutical properties. This study will attempt to provide further insight into the profile of olive phenolic compounds during fruit development and to identify the major genetic determinants of phenolic metabolism. Results The concentration of the major phenolic compounds, such as oleuropein, demethyloleuropein, 3–4 DHPEA-EDA, ligstroside, tyrosol, hydroxytyrosol, verbascoside and lignans, were measured in the developing fruits of 12 olive cultivars. The content of these compounds varied significantly among the cultivars and decreased during fruit development and maturation, with some compounds showing specificity for certain cultivars. Thirty-five olive transcripts homologous to genes involved in the pathways of the main secondary metabolites were identified from the massive sequencing data of the olive fruit transcriptome or from cDNA-AFLP analysis. Their mRNA levels were determined using RT-qPCR analysis on fruits of high- and low-phenolic varieties (Coratina and Dolce d’Andria, respectively) during three different fruit developmental stages. A strong correlation was observed between phenolic compound concentrations and transcripts putatively involved in their biosynthesis, suggesting a transcriptional regulation of the corresponding pathways. OeDXS, OeGES, OeGE10H and OeADH, encoding putative 1-deoxy-D-xylulose-5-P synthase, geraniol synthase, geraniol 10-hydroxylase and arogenate dehydrogenase, respectively, were almost exclusively present at 45 days after flowering (DAF), suggesting that these compounds might play a key role in regulating secoiridoid accumulation during fruit development. Conclusions Metabolic and transcriptional profiling led to the identification of some major players putatively involved in biosynthesis of secondary compounds in the olive tree. Our data represent the first step towards the functional characterisation of important genes for the determination of olive fruit quality.

Abstract Background The fruit fly Bactrocera oleae is the primary biotic stressor of cultivated olives, causing direct and indirect damages that significantly reduce both the yield and the quality of olive oil. To study the olive-B. oleae interaction, we conducted transcriptomic and proteomic investigations of the molecular response of the drupe. The identifications of genes and proteins involved in the fruit response were performed using a Suppression Subtractive Hybridisation technique and a combined bi-dimensional electrophoresis/nanoLC-ESI-LIT-MS/MS approach, respectively. Results We identified 196 ESTs and 26 protein spots as differentially expressed in olives with larval feeding tunnels. A bioinformatic analysis of the identified non-redundant EST and protein collection indicated that different molecular processes were affected, such as stress response, phytohormone signalling, transcriptional control and primary metabolism, and that a considerable proportion of the ESTs could not be classified. The altered expression of 20 transcripts was also analysed by real-time PCR, and the most striking differences were further confirmed in the fruit of a different olive variety. We also cloned the full-length coding sequences of two genes, Oe-chitinase I and Oe-PR27, and showed that these are wound-inducible genes and activated by B. oleae punctures. Conclusions This study represents the first report that reveals the molecular players and signalling pathways involved in the interaction between the olive fruit and its most damaging biotic stressor. Drupe response is complex, involving genes and proteins involved in photosynthesis as well as in the production of ROS, the activation of different stress response pathways and the production of compounds involved in direct defence against phytophagous larvae. Among the latter, trypsin inhibitors should play a major role in drupe resistance reaction.