Heterozygosity analysis of spontaneous 2n female gametes and centromere mapping of the diploid Hevea brasiliensis based on full-sib triploid populations

Key message Unreduced megagametophytes via second-division restitution were confirmed through heterozygosity analysis, and four candidate physical centromeres of rubber were located for the first time. The evaluation of maternal heterozygosity restitution (MHR) is vital in identifying the mechanism of 2 n gametogenesis and assessing the utilization value of 2 n gametes. In this study, three full-sib triploid populations were employed to evaluate the MHR of 2 n female gametes of rubber tree clone GT1 and to confirm their genetic derivation. The 2 n female gametes of GT1 were derived from second-division restitution (SDR) and transmitted more than half of the parental heterozygosity. In addition, low recombination frequency markers were developed, and four candidate physical centromeres of rubber tree were located for the first time. The confirmation that 2 n female gametes of rubber tree clone GT1 are derived from SDR provides insights into the molecular mechanisms of 2 n gametogenesis. In addition, the identified centromere location will aid in the development of centromeric markers for the rapid identification of the 2 n gametogenesis mechanism.