X-ray irradiation maintains soluble sugar content and regulates expression of genes related to sugar metabolism of figs (Ficus carica L. ‘Siluhongyu’)

Abstract

Fig is susceptible to lose fruit sensory quality due to its delicate skin and the natural bottom fruit pore. X-ray irradiation is an effective strategy for fruit preservation. This study investigated appearance and basic quality attributes of ‘Siluhongyu’ fig and evaluated the effects of X-ray on fig sugar metabolism and relative expression of genes. Results indicated that ‘Siluhongyu’ fig could be accepted by consumers with suitable overall dimension, soluble sugar, titratable acidity (TA), soluble protein, and dietary fiber contents. Sugar metabolism assay revealed that 3.0 kGy X-ray effectively inhibited the decline of glucose, fructose and sucrose contents. The starch degradation and the increase of amylase activity of figs were alleviated. In addition, the neutral invertase (NI), sucrose phosphate synthase (SPS), sucrose synthase (SS) and phosphofructokinase (PFK) activities in figs were activated by 3.0 kGy X-ray. About 22 % higher hexokinase (HK) activity was found in 3.0 kGy irradiated fruit than non-irradiated figs. Furthermore, 3.0 kGy X-ray upregulated gene expressions of NI, SS, HK, and PFK. The study proves that 3.0 kGy X-ray could be used as the feasible preservation means to regulate sugar metabolism and maintain quality of figs.