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.