Nitric oxide inhibits activities of PAL and PME enzymes and reduces chilling injury in ‘Santa Rosa’ Japanese plum (Prunus salicina Lindell).

Abstract

Studies were carried out to observe the effect of sodium nitroprusside (SNP) treatment (source of nitric oxide) on chilling injury, electrolyte leakage, malondialdehyde (MDA) content, phenylalanine ammonia lyase (PAL) and pectin methyl esterase (PME) activities during low temperature storage of Japanese plums cv. ‘Santa Rosa’. All SNP treatments significantly alleviated CI symptoms during entire period of cold storage. Among different treatments, fruits treated with SNP (0.5 mM) showed 71% lower incidence of CI than control. Minimum electrolyte leakage (49%), PAL (53.6 μmoles of cinnamic acid produced min−1 g−1FW) and PME activity (0.36 μmol min−1 g−1FW) were observed in 0.5 mM SNP treated plums and the maximum in control. The maximum retention of ascorbic acid (25.6 mg/100 g pulp) and antioxidant capacity (14.7 μmol Trolox g−1) was also exhibited by 0.5 mM SNP treated plums. Lowest MDA content (8.17 nmol g−1 FW) and anthocyanin content (592.7 mg/kg FW) were also found in the fruits treated with 0.5 mM SNP. Thus, it can be concluded that SNP is an easy method for application of nitric oxide to maintain fruit quality and extending shelf life by inhibiting fruit softening through interfering with PAL and PME activities during cold storage of ‘Santa Rosa’ plums.