Flutre, T. | bioRxiv Science

bioRxiv2020

The wild grape genome sequence provides insights into the transition from dioecy to hermaphroditism during grape domestication

Grapevine has a major economical and cultural importance since antiquity. A key step in domestication was the transition from separate sexes (dioecy) in wild Vitis vinifera ssp. sylvestris (V. sylvestris) to hermaphroditism in cultivated Vitis vinifera ssp. vinifera. While the grapevine sex locus is known to be small, its precise boundaries, gene content and the sex-determining genes are unknown. Here we obtained a high-quality de novo reference genome for V. sylvestris and whole-genome resequencing data of a cross. Studying SNP segregation patterns, gene content and expression in wild and cultivated accessions allowed us to build a model for sex determination in grapevine. In this model, up- and down-regulation of a cytokinin regulator is sufficient to cause female sterility and reversal to hermaphroditism, respectively. This study highlights the importance of neo-functionalization of Y alleles in sex determination and provides a resource for studying genetic diversity in V. sylvestris and the genomic processes of grapevine domestication.

plant biology↗

bioRxiv2019

Genetic diversity and structure of sweet chestnut (Castanea sativa Mill.) in France: At the intersection between Spain and Italy

ContextRenewed interest in European chestnut in France is focused on finding locally adapted populations partially resistant to ink disease and identifying local landraces. AimsWe genotyped trees to assess (i) the genetic diversity of wild and cultivated chestnut across most of its range in France, (ii) their genetic structure, notably in relation with the sampled regions, and (iii) relations with its neighbors in Spain and Italy. MethodsA total of 693 trees in 16 sampling regions in France were genotyped at 24 SSRs, and 1,401 trees in 17 sampling regions at 13 SSRs. ResultsGenetic diversity was high in most sampling regions, with redundancy between them. No significant differentiation was found between wild and cultivated chestnut. A genetic structure analysis with no a priori information found a low, yet significant structure, and identified two clusters. One cluster gathers trees from south-east France and Corsica (RPP1) and another cluster gathers trees from all other sampled regions (RPP2). A substructure was detected at 13 SSRs suggesting differentiation within both RPP1 and RPP2. RPP1 was split between south-east France and Corsica. RPP2 was split between north-west France, Aveyron, Pyrenees and a last cluster gathering individuals from several other regions. ConclusionThe genetic structure within and between our sampling regions is likely the result of natural events (recolonization after the last glaciation) and human activities (migration and exchanges). Notably, we provide evidence for a common origin of most French and Iberian chestnut trees, except those from south-east France that were associated with the Italian gene pool. This advances our knowledge of chestnut genetic diversity and structure, will benefit conservation and help our local partners valorization efforts.

genetics↗