Effect of spermidine and D-arginine treatments on ethylene synthesis in Xinjiang 'Saimaiti' apricot

Xinjiang 'Saimaiti' apricots in the green ripe stage were used as the experimental materials. The apricots were treated with spermidine (Spd) and o-arginine (D-Arg). Fruit firmness, ethylene production, 1-aminocyclopropane-1-carboxylic-acid (ACC) synthase activity, ACC oxidase activity and gene expression were studied. The results show that Spd treatment could delay the decline of fruit firmness and reduce ACC synthase and ACC oxidase activity through the inhibition of the relative expression of PaACS2 and PaACO, thus further reducing ethylene production and delaying senescence. Inhibition of polyamine synthesis due to D-Arg treatment can increase the activity of ethylene related enzymes and promote ethylene production. The results suggested that Spd treatment inhibits ethylene production. PaACS2 was the key gene involved in regulating the maturation and senescence of 'Saimaiti' apricots.