Effect of NAA on fruit softening and ethylene biosynthesis of '24-30' nectarine

【Objective】Changes of the fruit firmness and ethylene production in the fruit of nectarine‘24-30'during the late development period and the effect of postharvest NAA treatment were studied.【Meth-ods】The fruits of nectarine‘24-30'were used as materials. Fruit firmness and ethylene production aswell as the expression of ethylene biosynthesis genes(ACS1,ACS4,ACO1)and fruit softening relatedgene(PG1)under NAA treatment on the‘24-30'nectarine fruits was measured.【Results】Changes ofthe fruit firmness and ethylene production in the fruit were not obvious during the late development periodand after harvest,while the firmness decreased very greatly and the ethylene production increased rapidlyafter NAA treatment. with the increase of treatment concentration,the effect was more obvious. Real-time quantitative expression analysis showed that the expression of genes(PG1 and ACS1)was upregulat-ed under NAA treatment,which was more obvious under higher treatment concentration. NAA treatmenthad no obvious effect on the expression of genes(ACS4 and ACO1).【Conclusion】The fruits of‘24-30'can maintain high hardness due to the low level of ethylene production during the late development periodand after harvest,while the expression of ACS1 was upregulated under NAA treatment,and with the in-crease of ethylene production,the expression of fruit softening related gene(PG1)was upregulated,which resulted in fruit softening.