A Regulatory Network of Arabinogalactan Proteins, Glycosylation, and Nucleotide Sugars for Optimizing Mara des Bois Strawberries Postharvest Storage Quality

Arabinogalactan proteins (AGPs) and extensins influence cell wall assembly and regulate plant cell mechanical properties through interactions with extracellular matrix polymers. These proteins may play a key role in the biochemical events underlying postharvest treatments aimed at controlling fruit texture and turgor loss associated with senescence-related disorders. We studied the temporal and spatial accumulation patterns of extensin and AGP isoforms constitutively expressed along with the profiling of nucleotide sugars UDP-galactose, UDP-arabinose, UDP-glucuronic acid, and UDP-rhamnose in Mara des Bois strawberries under different storage conditions. We also assessed the expression timing of AGP-encoding genes (FvAFP4, FvAGP5) and genes involved in key steps of post-translational glycosylation (FvP4H1, FvGAT20, FvGAT7). Whereas extensins are down-regulated, AGPs are transcriptionally regulated by cold and cold-high CO₂ and post-translationally modulated after transfer to 20 °C. Based on their subcellular localization, molecular properties, isoform-specific glycosylation, UDP-sugar availability, and timing-regulated expression, AGPs are likely involved in cell wall assembly and modulation of mechanical properties. Consequently, they may influence fruit texture and enhanced softening resistance, potentially counteracting senescence-associated disorders through CO₂-responsive signaling mechanisms. Conversely, the decrease in both UDP-galactose levels and AGPs gene expression in non-cold-stored senescent strawberries at 20 °C further supports their relevance in AGPs biosynthesis regulation and underscores their potential as markers for improving postharvest storage strategies.