Silver arowana, Osteoglossum bicirrhosum, is sexually monomorphic, and
its sex determination mechanism is still poorly understood, posing a
significant challenge to its captive breeding efforts. To this end, we
assembled two high-quality chromosome-level genomes for both female and
male silver arowana, with scaffold N50 values of 10.6 Mb and 10.4 Mb for
female and male individuals, respectively. Combining re-sequencing data
of 109 individuals, we identified two sex-specific SNPs and confirmed a
ZW model of sex-determination in this ancient species. Both sex-specific
SNPs are located in about 26-kb upstream of foxl2 gene. We subsequently
propose a complex gene network in the sex determination process of
silver arowana, with foxl2 acting as the central player. The sex
chromosomes are homomorphic with a potentially recent origin, as linkage
disequilibrium analysis showed minor recombination suppression.
Furthermore, we successfully developed accurate molecular markers for
sex identification of silver arowana at each developmental stage,
significantly improving the reproductive efficiency and further
promoting the industrial development.