Targeted Capture of Homoeologous Coding and Noncoding Sequence in Polyploid Cotton

Targeted sequence capture is a promising technology in many areas in biology. These methods enable efficient and relatively inexpensive sequencing of hundreds to thousands of genes or genomic regions from many more individuals than is practical using whole-genome sequencing approaches. Here, we demonstrate the feasibility of target enrichment using sequence capture in polyploid cotton. To capture and sequence both members of each gene pair (homeologs) of wild and domesticated Gossypium hirsutum, we created custom hybridization probes to target 1000 genes (500 pairs of homeologs) using information from the cotton transcriptome. Two widely divergent samples of G. hirsutum were hybridized to four custom NimbleGen capture arrays containing probes for targeted genes. We show that the two coresident homeologs in the allopolyploid nucleus were efficiently captured with high coverage. The capture efficiency was similar between the two accessions and independent of whether the samples were multiplexed. A significant amount of flanking, nontargeted sequence (untranslated regions and introns) was also captured and sequenced along with the targeted exons. Intraindividual heterozygosity is low in both wild and cultivated Upland cotton, as expected from the high level of inbreeding in natural G. hirsutum and bottlenecks accompanying domestication. In addition, levels of heterozygosity appeared asymmetrical with respect to genome (A(T) or D(T)) in cultivated cotton. The approach used here is general, scalable, and may be adapted for many different research inquiries involving polyploid plant genomes

Low genetic diversity contrasts with high phenotypic variability in heptaploid Spartina densiflora populations invading the Pacific coast of North America

Species can respond to environmental pressures through genetic and epigenetic changes and through phenotypic plasticity, but few studies have evaluated the relationships between genetic differentiation and phenotypic plasticity of plant species along changing environmental conditions throughout wide latitudinal ranges. We studied inter‐ and intrapopulation genetic diversity (using simple sequence repeats and chloroplast DNA sequencing) and inter‐ and intrapopulation phenotypic variability of 33 plant traits (using field and common‐garden measurements) for five populations of the invasive cordgrass Spartina densiflora Brongn. along the Pacific coast of North America from San Francisco Bay to Vancouver Island. Studied populations showed very low genetic diversity, high levels of phenotypic variability when growing in contrasted environments and high intrapopulation phenotypic variability for many plant traits. This intrapopulation phenotypic variability was especially high, irrespective of environmental conditions, for those traits showing also high phenotypic plasticity. Within‐population variation represented 84% of the total genetic variation coinciding with certain individual plants keeping consistent responses for three plant traits (chlorophyll b and carotenoid contents, and dead shoot biomass) in the field and in common‐garden conditions. These populations have most likely undergone genetic bottleneck since their introduction from South America; multiple introductions are unknown but possible as the population from Vancouver Island was the most recent and one of the most genetically diverse. S. densiflora appears as a species that would not be very affected itself by climate change and sea‐level rise as it can disperse, establish, and acclimate to contrasted environments along wide latitudinal ranges

Supporting Spartina: Interdisciplinary perspective shows Spartina as a distinct solid genus

In 2014 a DNA-based phylogenetic study confirming the paraphyly of the grass subtribe Sporobolinae proposed the creation of a large monophyletic genus Sporobolus, including (among others) species previously included in the genera Spartina, Calamovilfa, and Sporobolus. Spartina species have contributed substantially (and continue contributing) to our knowledge in multiple disciplines, including ecology, evolutionary biology, molecular biology, biogeography, experimental ecology, environmental management, restoration ecology, history, economics, and sociology. There is no rationale so compelling to subsume the name Spartina as a subgenus that could rival the striking, global iconic history and use of the name Spartina for over 200 years. We do not agree with the arguments underlying the proposal to change Spartina to Sporobolus. We understand the importance of taxonomy and of formalized nomenclature and hope that by opening this debate we will encourage positive feedback that will strengthen taxonomic decisions with an interdisciplinary perspective. We consider the strongly distinct, monophyletic clade Spartina should simply and efficiently be treated as the genus Spartina

Challenges from Next Generation Sequencing analyses in polyploids: Assemblies, alignments, polymorphisms and data storage

International audienc

Les contrôles épigénétiques chez les plantes

International audienc

Ecological genomics and transcriptomics of Spartina

International audienc

Analyse de données transcriptomiques (approche RNA seq).

International audienc

Challenges from Next Generation Sequencing analyses in polyploids: Assemblies, alignments, polymorphisms and data storage

International audienc

Hybrididzation, polyploidy, genome evolution and adaptation in Spartina (Poaceae)

International audienc