Mechanism and Molecular Marker of Sex Identification in Dioecious Crops: Progress and Perspective

Dioecious plant species have great agricultural, industrial, and ecological value, though their sexual diamorphism is reflected only at the reproductive stage, making early sex identification a tough job. At early stage (seedling) sex identification in dioecious plants is very important for the breeder, farmer, and economic agricultural productivity. The present review presents a comprehensive methodology of sex determination mechanisms in dioecious plants consisting of cytological, biochemical, morphological, and molecular traits which is an unquestionable requirement required for sexual distinction in dioecious plant species. A special emphasis is focused on molecular marker approaches like Inter-Simple Sequence Repeat (ISSR), Random Amplified Polymorphic DNA (RAPD), Amplified Fragment Length Polymorphism (AFLP), and Sequence Characterized Amplified Region (SCAR) molecular markers, which have potentially enhanced sex determination accuracy and efficiency. These markers have been utilized successfully in a range of dioecious crops such as Pandanus spp., Carica papaya, Cannabis sativa, and Asparagus officinalis. The review also points out the RAPD and ISSR conversion into SCAR for enhancing reproducibility and specificity, along with modern transcriptomic techniques for identifying floral sex-specific genes in economically important plants. Collectively, this review highlights the growing application of molecular marker-based approaches in early and reliable plant sex determination and suggests a future roadmap for high-throughput and genome-assisted strategies in breeding programs.