An international team of breeders and genome scientists together with
biologists from the University of Georgia (UGA) have sequenced the genome of
garden asparagus as a model for sex chromosome evolution. This research is
the first confirmation of early models on how sex chromosomes diverge within
the same species.

While most flowering plants are hermaphrodites, garden asparagus plants are
typically either male (XY) or female (XX). However, YY "supermales" can be
produced in the greenhouse. Growers prefer all-male plants, because they
live longer and do not self-seed. Breeders produce all-male XY seed by
crossing an XX female with a YY supermale. Until now the differences between
asparagus X and Y chromosomes are not fully understood, and breeders are
unable to distinguish XY males from YY supermales without time-consuming
test crosses.

Identification of genes that determine sex paved the way for the development
and production of valuable hybrid asparagus plants. The research team found
that as predicted, linkage of a gene necessary for male function with a gene
stunting development of female organs on a small portion of the Y chromosome
was the starting point for the evolution of asparagus sex chromosomes.

[news.uga.edu]
volution-of-sex-chromosomes/