l-Cysteine hydrochloride delays senescence of harvested longan fruit in relation to modification of redox status

Longan fruit has a limited postharvest life due to aril breakdown, a typical senescence characteristics. In this study, effects of l-cysteine hydrochloride (LCH) on senescence of harvested longan fruit associated with modification of redox status were investigated. Application of LCH delayed aril breakdown and maintained fruit quality, accompanied by reduced H2O2 accumulation and alleviated protein oxidation. Furthermore, expression of several genes related to elimination of H2O2 and peroxide, APX and GST, regeneration of glutathione and ascorbic acid, GR and DHAR, were up-regulated by LCH. Moreover, LCH treatment well maintained the expression level of three oxidized-protein repair-related genes, Msr, MsrA5 and MsrB2. Additionally. LCH treatment inhibited expression of EGase, PLD and LOX. EGase was associated with degradation of cell wall, while PLD and LOX were associated with degradation of cell membrane. Overall, these findings suggested that LCH treatment enhanced anti-oxidant and oxidized-protein repair capacities, and maintained higher reducing state, which contributed to reducing oxidative damage and, thereby, delayed senescence of longan fruit.