Admixture mapping in interspecific Populus hybrids identifies classes of genomic architectures for phytochemical, morphological and growth traits

The genomic architecture of functionally important traits is key to understanding the maintenance of reproductive barriers and trait differences when divergent populations or species hybridize. We conducted a genome-wide association study (GWAS) to study trait architecture in natural hybrids of two ecologically divergent Populus species. We genotyped 472 seedlings from a natural hybrid zone of Populus alba and Populus tremula for genome-wide markers from reduced representation sequencing, phenotyped the plants in common gardens for 46 phytochemical (phenylpropanoid), morphological and growth traits, and used a Bayesian polygenic model for mapping. We detected three classes of genomic architectures: traits with finite, detectable associations of genetic loci with phenotypic variation in addition to highly polygenic heritability; traits with indications for polygenic heritability only; and traits with no detectable heritability. For the first class, we identified genome regions with plausible candidate genes for phenylpropanoid biosynthesis or its regulation, including MYB transcription factors and glycosyl transferases. GWAS in natural, recombinant hybrids represent a promising step towards resolving the genomic architecture of phenotypic traits in long-lived species. This facilitates the fine-mapping and subsequent functional characterization of genes and networks causing differences in hybrid performance and fitness

La couleur florale dans la famille des Gesneriaceae: Identification de flavonoïdes par spectrométrie de masse et analyses de l’expression des gènes de la voie biosynthétique des anthocyanines

Nous nous intéressons à la compréhension des bases chimiques et moléculaires des changements de pigmentation florale dans la sous-famille des Gesnerioideae (Gesneriaceae), principalement distribuée en Amérique tropicale. La couleur des fleurs a été étudiée selon leur composition en flavonoïdes. Parmi les 58 espèces de Gesnerioideae analysées, quatre types de compositions flavonoïques ont pu être identifiées: 1) fleurs à hydroxyanthocyanines (pelargonine, cyanidine, malvidine, delphinidine, petunidine), dont la couleur varie du rouge au violet ; 2) fleurs à déoxyanthocyanines (apigeninidine, luteolidine et columnidine), de couleurs rouges ou oranges; 3) fleurs à déoxyanthocyanines et hydroxyanthocyanines, dont le mélange de pigments présente des couleurs orange-rouge; 4) fleurs à flavones dépourvues d’anthocyanines, de couleur blanche. L’étude de l’expression des gènes biosynthétiques des anthocyanines par PCR quantitative a montré que les différences de pigmentations s’expliquent essentiellement par la régulation de la transcription de gènes structuraux intervenant tardivement dans la voie biosynthétique des anthocyanines (F3H, F3’H, DFR)

Integrating the ‘genomic mosaic’ view of species into studies of biotic interactions: a comment on Bernhardsson et al. (2013)

The co-occurrence of geographical structure in herbivore communities, metabolomes and defence genes in forest trees has been analysed in the context of ‘geographical mosaics’ of coevolution. A deeper understanding of these important issues will require full integration of a ‘genomic mosaic’ view of species into community ecology

Genetic and molecular landscapes of the generalist phytopathogen Botrytis cinerea.

UNLABELLED: Botrytis cinerea Pers. Fr. (teleomorph: Botryotinia fuckeliana) is a necrotrophic fungal pathogen that attacks a wide range of plants. This updated pathogen profile explores the extensive genetic diversity of B. cinerea, highlights the progress in genome sequencing, and provides current knowledge of genetic and molecular mechanisms employed by the fungus to attack its hosts. In addition, we also discuss recent innovative strategies to combat B. cinerea. TAXONOMY: Kingdom: Fungi, phylum: Ascomycota, subphylum: Pezizomycotina, class: Leotiomycetes, order: Helotiales, family: Sclerotiniaceae, genus: Botrytis, species: cinerea. HOST RANGE: B. cinerea infects almost all of the plant groups (angiosperms, gymnosperms, pteridophytes, and bryophytes). To date, 1606 plant species have been identified as hosts of B. cinerea. GENETIC DIVERSITY: This polyphagous necrotroph has extensive genetic diversity at all population levels shaped by climate, geography, and plant host variation. PATHOGENICITY: Genetic architecture of virulence and host specificity is polygenic using multiple weapons to target hosts, including secretory proteins, complex signal transduction pathways, metabolites, and mobile small RNA. DISEASE CONTROL STRATEGIES: Efforts to control B. cinerea, being a high-diversity generalist pathogen, are complicated. However, integrated disease management strategies that combine cultural practices, chemical and biological controls, and the use of appropriate crop varieties will lessen yield losses. Recently, studies conducted worldwide have explored the potential of small RNA as an efficient and environmentally friendly approach for combating grey mould. However, additional research is necessary, especially on risk assessment and regulatory frameworks, to fully harness the potential of this technology