Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.

Alternative splicing (AS) can generate significant protein variation from a single gene. While the basic process of AS has been known for some time, little is known about how AS varies across species. In addition, there are many unanswered questions about the role of AS in plant responses to abiotic stress. In this study of the model plant species, Arabidopsis thaliana, and a native California mustard, Boechera depauperata, researchers report that the genes that undergo AS are distinct in each species. This provides evidence that AS plays an important and species-specific role in the plant stress response.

Thermotolerance is a property of all organisms, but owing to their sessile nature, this trait is particularly important in plants. Basal thermotolerance is based on inherent tolerance to heat stress. Acquired thermotolerance is attained through stress-induced gene expression, often of those genes encoding heat shock proteins (HSPs). Both basal and acquired thermotolerance have been extensively studied in model species such as Arabidopsis thaliana (L.) Heynh., but much less is known about thermotolerance in wild plant species. The aims of this study were to examine the basal and acquired thermotolerance of four species of Boechera, and of A. thaliana. Mots-clés : Arabidopsis, Boechera, fluorescence de la chlorophylle, expression génique induite par la chaleur, stress thermique, thermotolérance.

Global surface temperatures are expected to rise throughout the 21st century and will negatively impact plant growth and reproduction. Thus, it is imperative that we deepen our understanding of plant thermotolerance. The examination of native plant species that have evolved tolerance to high temperatures can provide crucial information on how plants can adapt to climate change. Boechera (Brassicaceae), a large genus that is native to North America, is highly thermotolerant and can maintain photosynthetic activity at high temperatures. Here we report results of transcriptomic studies that seek to reveal possible thermotolerance mechanisms in B. depauperata. Analysis of RNA-seq datasets from heat stressed B. depauperata and Arabidopsis thaliana plants identified significant differences in how each of these species responds to identical heat stress conditions. The most highly upregulated heat-stress genes in A. thaliana includes the well-characterized heat-shock genes. In contrast, the Boechera heat stress response is composed of: novel genes that lack orthologs in other genomes, genes coding for proteins of uncharacterized function, and genes coding for proteins associated with the unfolded protein and ER stress responses. In addition, genes that are protective of photosynthetic capacity are also differentially upregulated in B. depauperata.