Female gametophyte development in flowering plants is a highly intricate process involving a series of tightly regulated biological events, including the establishment and differentiation of a macrospore mother cell (MMC), the formation of a functional macrospore (FM), and the subsequent development of the embryo sac. The seamless progression of these events is crucial for the completion of sexual reproduction and the alternation of generations in plants. Small RNAs are ubiquitously present in eukaryotic organisms. Based on their biogenesis, function, and involvement in biological pathways, plant small RNAs are primarily categorized into four classes: miRNAs (microRNAs), ta-siRNAs (trans-acting-siRNAs), hc-siRNAs (heterochromatic-siRNAs), and nat-siRNAs (natural antisense transcript-derived siRNAs). Current studies show that small RNAs play an important role in plant reproductive development, such as female gametophyte development and ovule development. In this review, we systematically elucidate the biogenesis and molecular mechanism of small RNAs and summarize the latest research advances on their roles in regulating megasporogenesis and megagametogenesis in plants. The aim of this review is to provide insights into the mechanisms underlying plant reproductive development through the lens of small RNAs, offering a theoretical foundation for improving crop quality, yield, genetic improvement, and breeding.

The female gametophyte is central to the reproductive success of flowering plants, with its development being tightly controlled by an intricate network of genes and signaling pathways. A deeper understanding of these regulatory mechanisms is essential for uncovering the complexities of plant growth and development. Recent studies have shed light on various aspects of female gametophyte development, highlighting the role of specific gene and signaling networks. Among these, the ERECTA family of leucine-rich repeat receptor-like kinase (RLK) in Arabidopsis thaliana has emerged as a key player, influencing multiple biological processes, particularly those governing reproductive development of the female gametophyte. This review focuses on the significant progress made in understanding the ERECTA family’s involvement in germline cell development, emphasizing its functional roles and signaling mechanisms in female gametophyte development.

The ubiquitin–proteasome system (UPS) is a highly conserved protein degradation pathway in eukaryotic cells. Through precisely controlled proteolysis of key regulatory proteins, the UPS plays a particularly critical role in plant sexual reproduction, where precise spatiotemporal regulation is essential. The UPS governs multiple aspects of plant sexual reproduction, including male and female gametophyte development, pollen–pistil interactions, double fertilization, and post-fertilization embryogenesis and endosperm development. Among UPS components, E3 ubiquitin ligases play a central role by mediating the spatiotemporal degradation of key proteins, while E2 conjugating enzymes and deubiquitinating enzymes also make essential contributions. Through cross-species and cross-stage comparisons, we find that the UPS exhibits conserved regulatory logic—including cell-cycle gating, spatial control of protein accumulation, and signal integration—while also having evolved lineage-specific functional diversification. In this review, we systematically synthesize UPS functions across the reproductive cycle and highlight persistent knowledge gaps, aiming to provide an integrated framework and a reference for future studies investigating the regulatory roles of the UPS in plant sexual reproduction.