Postharvest sodium nitroprusside treatment maintains storage quality of apple fruit by regulating sucrose metabolism

Quality loss of apples during storage is a worldwide problem. In this study, ‘Fuji’ apples were treated with 1.0 mmol L−1 sodium nitroprusside (SNP) to investigate its effects on storage quality and sucrose metabolism. The results showed that SNP treatment delayed the timing of the maximum respiratory rate, delayed softening and losses of ascorbic acid (AsA), titratable acid (TA) and soluble solids content (SSC) of the fruit. SNP treatment increased the activities of sucrose phosphate synthase (SPS) and sucrose synthase synthesis (SS-s), and suppressed the activities of sucrose synthase-cleavage (SS-c), neutral invertase (NI) and acid invertase (AI). MdSPS, MdSS, MdNI, hexokinase (HK) and fructokinase (FK) genes were up-regulated by SNP. The results suggest that SNP might modulate sucrose metabolism and delay loss of fruit quality.