Transcriptomic and biochemical insights into LOX pathway aroma biosynthesis during ripening of Ziziphus jujuba Mill....

Aroma is a critical determinant of fruit quality, largely synthesized through the lipoxygenase (LOX) pathway. We hypothesized that the dynamic regulation of the LOX pathway during jujube fruit ripening governs the distinct evolution of its key aroma compounds. This study used HS-SPME coupled with GC-MS to profile aroma compounds in jujube during ripening. Semi-quantitative analysis revealed hexanal (1160-1870 μg/kg) and (E)-2-hexenal (1470-3180 μg/kg) as the most abundant aldehydes, followed by benzaldehyde and (E)-2-pentenal. Odor activity value (OAV) analysis identified hexanal, (E)-2-hexenal, and (E)-2-nonenal as the key aroma compounds. LOX enzyme activity increased from 277 U/g to 711 U/g during ripening, while ADH and AAT activities showed fluctuating trends. Transcriptome analysis revealed 12 candidate transcripts involved in aroma synthesis, with multivariate statistical analysis demonstrating coordinated changes in gene expression associated with volatile accumulation. Our findings verify the hypothesis that LOX pathway regulation drives aroma evolution during jujube ripening and provide a genetic foundation for targeted quality improvement in jujube fruits.