Biaxially oriented polyethylene (BOPE) and exogenous H2S extend strawberry shelf-life by increasing antioxidant activity and inhibiting pigment accumulation

Hydrogen sulfide (H 2 S) is a gaseous signaling molecule that extends the postharvest storage period of fruit. Biaxially oriented polyethylene (BOPE) films are widely used in fruit packaging due to their excellent properties. By analyzing the phenotypic characteristics of strawberry fruits by comparing with the control, PE and BOPE or in combination with H 2 S at 4 ℃, it was shown that the H 2 S+BOPE treatment reduced decay and water loss, and maintained the best lustre and firmness than other groups. A total of 7,258 co-differentially expressed genes (DEGs) were identified by comparing H 2 S, H 2 S+PE and H 2 S+BOPE with Control by transcriptome analysis. GO, WGCNA and KEGG analyses showed that DEGs were mainly enriched in starch and sucrose metabolism, pigment metabolism and antioxidant activity from the MEyellow and MEblack modules. Moreover, these candidate genes were screened, and the expression level of CHS , PAL and DFR were significantly decreased in H 2 S+BOPE group than other groups by RT-qPCR. Physiological assessments indicated that H 2 S+BOPE treatment significantly delayed chlorophyll degradation, anthocyanin accumulation and TA content, increased reducing sugar content, carotenoid and POD activity, and maintained low MDA content in strawberries. PCA and heatmap showed that POD and pigments were main factors and the correlation analysis proved that POD activity exhibited a positive correlation with the expression of DFR (0.57) and bHLH3 (0.56), carotenoid content (0.54), and it showed a negative correlation with chlorophyll contents (-0.37). These results indicated that BOPE could effectively improve the appearance and antioxidant activity of strawberry fruits, thereby prolonging their postharvest storage period.