​In 1923, Kathleen Blackburn demonstrated the existence of sex chromosomes in plants by studying Silene latifolia, a few years after Nettie Stevens’ discovery of these chromosomes in animals. It was not until 2014 that the first master gene of sex determination in plants was identified, in persimmon.

X and Y: highly complex chromosomes

Sex chromosomes contain non-recombining regions rich in repeated sequences, making them extremely difficult to sequence. In 2003, six million dollars were invested to sequence 65 Mb of the human Y chromosome. By comparison, the Y chromosome of S. latifolia reaches 550 Mb! This makes the plant a true genomic challenge t.

A century after Blackburn’s discovery, thanks to the instruments and expertise of Genoscope, an international consortium has decoded these chromosomes using a new long-read sequencing technology.

Shedding light on sex determination in plants

The researchers analyzed mutants with altered sexual phenotypes (hermaphrodites or asexual plants) that carried deletions on the Y chromosome. In doing so, they identified the sex-determining genes that were lost in these mutants. Their work also revealed chromosomal rearrangements that halted recombination and promoted the accumulation of repeated sequences on both the Y and X chromosomes.

These advances open new perspectives for agriculture, particularly by optimizing the production of dioecious plants (species in which unisexual male [staminate] and female [pistillate] flowers are borne on separate individuals), such as grapevine, hops, or date palm. Early identification of plant sex could improve yield and cultivation. Manipulating sex-determining genes could also facilitate controlled breeding and the creation of self-fertile hermaphroditic varieties, thereby increasing agricultural efficiency.​

Contact : karine.labadie@cea.fr