Effects Of 1-Methylcyclopropene On Storage Behavior And The Changes Of Soluble Proteins Of 5 Apple Cultivars

The effects of 0.5μL·L-1 1-methylcyclopropene (1-MCP) on the respiration, ethylene production, ACO activity, storage quality and the changes of soluble proteins in harvested apples of 5 cultivars were studied during the storage at room temperature. The main purposes of this study were to find out the proteins related to apple senescence and the difference in those proteins among 5 apple cultvars. The relationship between those proteins and ethylene was also discussed.The main results acquired were as follows:(1) 0.5μL·L-1 1-MCP significantly slowed down the decrease of the flesh firmness and titratable acids of 5 cultivars apples during storage. So, the fruit quanlity was well retended by 1-MCP treatment. A difference in the effect of 1-MCP on soluble solids was found among 5 cultivars. 1-MCP inhibited the decrease of the total soluble solids of'Gala','Qinguan'and'Fuji'apples, but had no obvious effect in'Red Delicious'and'Pink Lady'apples.(2) 0.5μL·L-1 1-MCP significantly inhibited the respiration and ethylene production in'Qinguan','Fuji'and'Pink Lady'apples during the storage at room temperature. The reduction of ethylene production was closely related to the inhibition of ACO activity. There was a significant difference in ethylene synthesis capacity and ACO activity among apple varieties. Ethylene production and ACO activity in'Qinguan'apples were much higher than'Fuji'and'Pink Lady'apples.(3) The SDS-PAGE analysis of soluble proteins in 5 cultivars indicated that 7 protein bands (97.2, 38.3, 37.0, 28.7, 27.2, 19.6 and 18.6 kD) in untreated fruits were related to apple ripening and senescence. Some differences existed among the different cultivars. 37.0 kD protein appeared in'Gala'and'Qinguan'fruits, and 28.7 kD protein content decreased in'Gala'and'Qinguan'fruits but it kept stable in other cultivars. 27.2 kD protein expressed in fruits of other cultivars except'Gala'. 18.6 kD protein only expressed in'Red Delicious','Qinguan'and'Fuji'fruits.(4) In the fruits treated with 0.5μL·L-1 1-methylcyclopropene, the accumulation of 97.2, 38.3, 37.0, 27.2, 19.6 and 18.6 kD proteins was delayed or reduced, while the degradation of 28.7 kD protein in'Gala'and'Qinguan'fruits was slowed down. It is speculated that the proteins influenced by 1- methylcyclopropene are ethylene-relevant proteins.