| Currently, China's'Fuji'apple planting area is large, so domestic main consumption of fresh apple is 'Fuji'. Therefore, how to store'Fuji'apple preferably, improve quality reduction caused by the change of fruit essence structure, so that we can meet the public's daily needs, it has become an problem which urgently need to be solved in the practice of the apple production. At the same time, during the production process, a large number of apple in post harvest is transported into the cold storages for a period of time firstly, and then is transferred to controlled atmosphere storages and sprayed with a certain concentration of 1-MCP.The untimely disposal to postharvestapplescausesmany apples'commodity value declined sharply in the late storage, and results inserious economic losses and waste of resources. What's more, during thestorage, softening process once started, it will become difficult to slow down and control. Therefore, timely treatment and storage, inhibiting related physiological activities of apple, delayed fruit ripening and softening process, have important significance to ensure'Fuji'apple's texture during storage and the value of commodity.In addition, there are many studies about the apple cell wall degrading enzymes, but there exists which interaction relation amongthese enzymes, does the geneexpression get any inner connection, how is the softening processof 'Fuji' appleduring long-term controlled atmosphere storage, there is a lack of systematic explanation about all of questionsat present.In order to solve the above problems, experiments were made to determine the fruit firmness, soluble solid content, pH value and the content of pectin, cell wall degrading enzymes activities (including PG?PME?PL?EG??-Gal and a-L-Af), fruit softening related genes expression(including PG?PME?PL?EG??-Gal??-L-Af??-xyl?AM? LOX?SPS and XET), and Pearson correlation detection of the above test project about 'Fuji'duringdifferent storage.The main results obtained are as follows:1. Changes of fruit quality in different treatments during storage: ?'Fuji'apple's firmness changeswas not significant (p>0.05) during storage 0 to 4 months, then began to slow down23.18%,8.48%,18.84%in 6th month, finally it tended to be flat.?The trend of fruit soluble solid content was arched, a slow increase, followed by a decline in the mid or late storage. Among them, the soluble solids content of CA group began to decrease from storage for 4 months, with the other two groups reduce from storage for 6months, and CAM group was high significantly (p<0.05) than DECAM group in soluble solids content. ?pH values continued to increase throughout the storage period, and CAM group was low significantly (p<0.05) than DECAM group in pH values.2. CAM treatment could significantly(p<0.05)inhibite the activity of PG, PME, PL, EG and the expression ofsoftening-related genes during the storage period.1-MCP treatmenttime of DECAM group had a certain inhibitory effect on the enzyme activities andsoftening genes, but it was significantly (p<0.05)lower than that of the CAM group.Therefore, the pectin content was low significantly (p<0.05) than CAM group about 19.33% in 8 monthsso that the apples quality of DECAM group was worse. So, it is very important to deal the apple timely with the 1-MCP.3. The activity of PME remaineda high level during the whole storage period, so we speculatedthat PME acted on the whole softening storage period, while PG kept a low standard activity in first 4 months and reached a peak until 6th month, it showed that PG acted primarily in the late stage of softening. In addition, PL were not significant or extremely significant correlation(p>0.05) with fruit firmness and pectin content changes,therefore, PL ia not a key enzyme of 'Fuji'apple during the period of after-ripening and softening.Hydrolysis of ?-Gal and a-L-Af occurred in the whole storage period, and with advance ofsoftening, hydrolysis was graduallystrengthened, so the two enzymes'activities increased without aobvious peak value.4. The test proved that activities of the three enzymes in the cell wall degrading enzymes in the'Fuji'apple includingEG, P-gal and a-L-Af weresignificantly (p< 0.01) affected by the corresponding gene expression. PG, PME and PL werenot significantly (p>0.05) affected by gene expression. During storage, gene expression of PME, EG and AMwere significantly correlated with apple'sfirmness (p<0.05).Gene expression of PL, ?-Gal, a-L-Afand XETwere significantly correlated with apple'sfirmness extremely (p?0.01).In summary, timely and postharvest apples 1-MCP treatment can effectively inhibit the expression of genes and cell wall degrading enzymes softening activity, slowing the degradation of pectin, so as to maintain storage quality of apple. In addition, not all the genes will have a significant effect on the activity of the corresponding enzyme activity, the specific regulatory mechanism needs further exploration. |
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