Sex chromosomes
Genetic mapping and genome sequencing revealed a large non-recombining
region spanning 124 Mb on chromosome-8 that functions as the
sex-determining region in C. panzhihuaensis (Lui et al .,
2022). Assembly of the male-specific Y chromosome region further
revealed a candidate sex determination gene encoding a MADS-box
transcription factor named MADS-Y. This gene and its autosomal paralog
showed sex-specific expression patterns, with MADS-Y exclusively
expressed in males. MADS-Y represents a potentially conserved mechanism
for sex determination originating before the divergence of cycads andGinkgo over 200 million years ago (Liao et al. , 2020). The
identification of this master regulator provides key insights into the
genetic control of sex determination in cycads, the most ancient
dioecious seed plant lineage.