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

AGAP : équipe GE2popBackground: A key step in domestication of the grapevine was the transition fromseparate sexes (dioecy) in wild Vitis vinifera ssp. sylvestris (V. sylvestris) to hermaphroditismincultivated Vitis vinifera ssp. sativa (V. vinifera). It is known that V. sylvestris has an XY systemand V. vinifera a modified Y haplotype (Yh) and that the sex locus is small, but it has notpreviously been precisely characterized.Results: We generate a high-quality de novo reference genome for V. sylvestris, onto whichwe map whole-genome re-sequencing data of a cross to locate the sex locus. Assembly ofthe full X, Y, and Yh haplotypes of V. sylvestris and V. vinifera sex locus and examining theirgene content and expression profiles during flower development in wild and cultivatedaccessions show that truncation and deletion of tapetum and pollen development geneson the X haplotype likely causes male sterility, while the upregulation of a Y allele of acytokinin regulator (APRT3) may cause female sterility. The downregulation of this cytokininregulator in the Yh haplotype may be sufficient to trigger reversal to hermaphroditism.Molecular dating of X and Y haplotypes is consistent with the sex locus being as old as theVitis genus, but the mechanism by which recombination was suppressed remainsundetermined.Conclusions: We describe the genomic and evolutionary characterization of the sex locusof cultivated and wild grapevine, providing a coherent model of sex determination in thelatter and for transition from dioecy to hermaphroditism during domestication