Arabinogalactan proteins: Decoding the multifaceted roles in plant reproduction

Arabinogalactan proteins (AGPs) are highly glycosylated cell wall proteins essential for plant growth and reproduction. AGPs are extensively decorated with arabinogalactan polysaccharides, composed primarily of arabinose and galactose, along with minor sugars such as glucuronic acid, fucose, and rhamnose. Their glycosylation patterns and glycosylphosphatidylinositol anchor enable interactions with receptors, modulating signal transduction pathways critical for reproduction. AGPs also associate with cell wall components like pectin and hemicellulose, impacting cellulose deposition and cell wall integrity. Recent research highlights AGPs' role as calcium (Ca²⁺) capacitors, regulating Ca²⁺ storage and release during crucial reproductive stages. Despite significant progress, their precise molecular mechanisms remain elusive. In this review, we explore the multifaceted roles of AGPs in plant reproduction, shedding light on the recent progress in their involvement in signalling pathways, cell wall interactions, and Ca²⁺ homeostasis, while highlighting the ongoing research needed to fully understand their mechanisms in reproductive success.