| Fruit quality includes appearance quality and internal quality.Appearance quality consists of fruit size,color,shape,etc,while internal quality mainly contains soluble sugar,titratable acid,vitamin C,mineral elements,and so forth.Among them,color index and sugar components are the most influencial factors of fruit quality.In this research,persimmon fruits were used as materials,the fundamental physiological indexes were measured first,then the internal quality sugar composition of fruits,comprising analysis of sugar components and their contents,as well as enzyme activities related to sucrose metabolism.Furthermore,Effects of postharvest chitosan,salicylic acid and ethephon treatments on fruit color and sugar in two sweet persimmon cultivars were investigated.Flnally,differentially expressed glycometabolic genes during fruit development were excavated by transcriptional analysis.These findings may provide theoretical and practical reference for improving the quality of persimmon fruit.The main results were as follows:1.Physiological indexes of 'Xingfang' persimmon fruits from S1 to S7 different developmental stages were determined.Results showed that the single fruit weight,TSS,transverse diameter and longitudinal diameter continued to increase,with the ranges of 94.47-178.38 g,12.51-16.62 °Brix,61.54-72.25 mm,41.64-51.20 mm,respectively.Fruit color gradually turned from green to red,and reached the most red in S7 period,in which H° decreased from 102.03° to 60.89°.Fruit firmness continued to decrease,the value of S1 period was the highest,while that of S7 period was the lowest,with the levels of 28.08 N and 8.25 N,respectively.2.The contents of sugar components in different developmental stages of 'Xiaofangshi'persimmon fruit were determined.It was found that the sugar composition contents in fruit were arrayed from the highest to lowest as glucose,fructose and sucrose.The sucrose content was the lowest,which was significantly lower than that of glucose and fructose.Contents of glucose and fructose were in a rising tendency.The content of glucose,fructose and sucrose varied from 45.81 to 86.71 mg/g,19.38 to 49.77 mg/g and 0.26 to 4.63 mg/g,respectively.The sugar composition and content in the fruit of different persimmon varieties were also measured.The results showed that the sugar components and their contents were similar to those of'Xiaofangshi' persimmon fruit.3.The activities of sucrose metabolism related enzymes in 'Xiaofangshi' persimmon fruits during development were analyzed.The findings demenstrated that the change tendency of NI and S-AI activities were the same,increased first and then decreased,with the highest activities at S4 stage.The activities of NI and S-AI range was 76.21-128.22 ?g/min/g FW and 83.90-32.20?g/min/g FW,respectively.They had significantly negative(r=-0.792*)and negative correlations(r=-0.429)with sucrose content.SS(synthetic direction)and SPS activities were similar,with firstly declined and then increased on the whole.The activities of SS(synthetic direction)and SPS range was 648.21-394.96 ?g/min/g FW and 506.06-173.08 ?g/min/g FW,respectively.They had extremely significantly positive(r=0.891**)and significantly positive correlations(r=0.862*)with sucrose content.Mature fruits of five sweet persimmon cultivars and five astringent persimmon cultivars were also used to determine the activities of sucrose metobolic enzymes,and differences were found between cultivars.4.Determination of Effects of postharvest chitosan,salicylic acid and ethephon treatments on fruit color,firmness,TSS,sugar composition and enzyme activities related to sucrose metabolism in 'Zenjimaru' and 'Jiro' sweet persimmon fruit during storage at room temperature after different treatments.The results showed that lOg/L chitosan and 40mg/L salicylic acid treatment had a good effect on maintaining good quality and extending postharvest storage period of persimmon fruit.Among them,the treatment effect of chitosan was more prominent.500mg/L ethephon treatment promoted the chlorosis of the pericarp and enhanced the ripening period.5.64.74 Gb Clean Data was obtained by sequencing the nine fruit samples from S1,S4,and S7 stages of 'Xiaofangshi' persimmon fruit.After clean data assembly,75714 pieces of Unigene were acquired.After comparison with the databases of COG,GO,KEGG and NR,33404 annotations of Unigene were identified in the final.differentially expressed genes screening,It is found that the differential expression is the most obvious for S1-vs-S7 with a total of 3757 genes,of which the number of up-regulated genes is 1279,while the number of down-regulated genes is 2478.Throughthe KEGG pathway analysis of differentially expressed genes,there were 232,1115,and 59 differential genes in the three groups of comparisons,i.e.S1-vs-S4,S1-vs-S7 and S4-vs-S7,which were mapped to 73,117,and 38 metabolic pathways,and 18 sucrose metabolic genes with significant differenceswere screened. |
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