Transcriptome analysis reveals the molecular mechanisms of mucilage biosynthesis during Artemisia sphaerocephala seed development

Seed mucilage is a polysaccharide with significant physiological, ecological, and economic value; however, both its biosynthesis pathway and molecular regulatory mechanisms remain unclear. Artemisia sphaerocephala is an important sand-fixed windbreak plant that is widely distributed across the deserts of Northwest China, with seeds that are rich in mucilage. For this research, seven different developmental stages of A. sphaerocephala seeds were employed as samples. The mucilage accumulation patterns were analyzed, and the differentially expressed genes (DEGs) involved in the biosynthesis of mucilage were identified via RNA sequencing. The results revealed that during the rapid accumulation period (10-30 days after flowering), the mucilage content increased from 0 to 49.42 %. Up-regulated expressed phosphoglucomutase (pgm) and uridine diphosphate glucose pyrophosphorylase (UGPase), and down-regulated expressed UDP-glucose 4-epimerase (GALE), UDP-glucose 6-dehydrogenase (UGDH), and UDP-glucose 4,6-dehydratase (RHM) led to the accumulation of UDP-glucose (UDP-Glc). Additionally, highly expressed UDP-apiose/xylose synthase (AXS) and minimally expressed UDP-arabinose 4-epimerase (UXE) led to the accumulation of UDP-xylose (UDP-Xyl). The MYB-bHLH-WD40 (MBW) complex and APETALA2 (AP2) were the primary transcription factors that regulated the biosynthesis of mucilage in A. sphaerocephala seeds. This study might assist with elucidating the molecular regulatory mechanisms of the seed mucilage biosynthesis process, while establishing a foundation for the application of mucilage associated genes in genetic breeding.