Key to better asparagus identified in evolution of sex chromosomes
Working with an international team of breeders and genome scientists, plant biologists at the Institute of Biosciences and BioResources (IBBR), National Research Council of Italy (CNR), have sequenced the genome of garden asparagus as a model for sex chromosome evolution. The work sheds light on longstanding questions about the origin and early evolution of sex chromosomes and at the same time serves as a foundation for asparagus breeding efforts.
Their research, the first confirmation of early models on how sex chromosomes diverge within the same species, was published today in Nature Communications.
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The asparagus genome sheds light on the origin and evolution of a young Y chromosome
Alex Harkess, Jinsong Zhou, Chunyan Xu, John E. Bowers, Ron Van der Hulst, Saravanaraj Ayyampalayam, Francesco Mercati et al. 2017
Abstract
Sex chromosomes evolved from autosomes many times across the eukaryote phylogeny. Several models have been proposed to explain this transition, some involving male and female sterility mutations linked in a region of suppressed recombination between X and Y (or Z/W, U/V) chromosomes. Comparative and experimental analysis of a reference genome assembly for a double haploid YY male garden asparagus (Asparagus officinalis L.) individual implicates separate but linked genes as responsible for sex determination. Dioecy has evolved recently within Asparagus and sex chromosomes are cytogenetically identical with the Y, harboring a megabase segment that is missing from the X. We show that deletion of this entire region results in a male-to-female conversion, whereas loss of a single suppressor of female development drives male-to-hermaphrodite conversion. A single copy anther-specific gene with a male sterile Arabidopsis knockout phenotype is also in the Y-specific region, supporting a two-gene model for sex chromosome evolution.
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An online version of the paper is available at https://www.nature.com/articles/s41467-017-01064-8
Contact: Francesco Mercati, +39 091 6574578, francesco.mercati@ibbr.cnr.it
