| In this study,by using 'Yourou' and 'Bungo' as materials of primus mume and'Sungold' as material of apricot,sugar and acid content were measured during different growth stages of fruit by HPLC and activity determination of organic acid metabolizing enzymes,finally using molecular biology method of real-time fluorescence quantitative detection of organic acid related genes,find the reasons of the difference of organic acid and the main regulation of organic acids in prunus mume and apricot.1.Through the determination of prunus mume and apricot fruit in different periods of the relevant indicators,we found that the prunus mume and apricot fruit in the development of the law of change in the double S-curve.In the process of development,the‘Yourou'and'Sungold' belong to the early maturing species,have reached maturity in late May,and'Bungo' in early June,late maturity,the trend of fruit growth is fast-slow-fast.The development trend of horizontal and vertical and lateral diameter of prunus mume and apricot were basically the same,the weight increased rapidly from the second stage and the fastest increase in third stage.lt is indicated that this stage is the key period for the accumulation of important fruits and it is also the key to determine the size and quality of fruits.2.The organic acids of prunus mume and apricot are mainly composed of citric acid,malic acid,tartaric acid,oxalic acid and acetic acid.The main content of malic acid and acetic acid in the fruit of their young fhuit period,dominated by citric acid and malic acid in the mature period,several other low acid content.During the growth and development,the citric acid of prunus mume and apricot rose continuously,and the accumulation of the citric acid from the hard core to the fading period was relatively fast.Malic acid was first increased and then decreased rapidly,and then decreased to the lowest level.In the mature period,the content of citric acid are accounted for more than 70%of the total acid in prunus mume and apricot,the content of citric acid in 'Yourou' was 37.89 mg·g-1;the content of citric acid in 'Bungo' was 23.24 mg·g-1,the content of citric acid in‘Sungold'was 12.76 mg·g-1.Therefore,the difference of organic acids is mainly due to the different content of citric acid.3.The soluble sugar of prunus mume and apricot was mainly composed of sucrose,fructose,glucose and sorbitol.During Fruit Development,the sucrose content of prunus mume and apricot increased continuously,from the hard core to the physiological maturity.In the early stage of 'Sungold' and 'Bungo' fruit development,glucose increased,reached the maximum at the hard core stage,and decreased in the later stage of development.However,the glucose content of the 'Yourou' showed a declining trend in the whole process.The sorbitol content have the same trend and showed the first increase and then decrease in prunus mume and apricot.At maturity,the sugar content of the 'Yourou'is 14.09 mg·g-1,accounting for about 71.95%of the total sugar;the sugar content of the'Bungo' is 17.9 mg·g-1,accounting for about 67%of the total sugar;the sugar content of the'Sungold' is 60.02 mg·g-1,accounting for about 63.3%of the total sugar.The results showed that sucrose was the most important component of sugar,and it could be seen that the prunus mume and apricot belonged to sucrose accumulation fruit during development.4.In order to study the reason of the difference of organic acid formation were determined by‘Yourou','Bungo','Sungold' fruit organic acid metabolizing enzyme activity.During fruit development,through the correlation analysis,CS,NAD-IDH,Cyt-ACO is a key enzyme in the metabolism of citric acid and the CS plays a major role in different periods.During the development of 'Bungo',the CS and NAD-IDH are the key enzymes in the metabolism of citric acid.In the process of development,the PEPC and ME are the key enzymes of malic acid metabolism in prunus mume and apricot fruit.the PEPC is an enzyme that promotes the synthesis of malic acid and the ME is malic acid degrading enzyme,the two enzymes interact to regulate the content of malic acid.The results showed that the difference of the organic acids was mainly caused by the different activities of CS,PEPC and ME.Therefore,the regulation of PEPC and ME enzyme activity in the early stage of fruit development,the regulation of CS activity in the later stage of development can reduce the content of organic acid.5.By using Real-time PCR to determine the Organic acid related gene in prunus mume and apricot,lt was found that the CS gene of 'Yourou' and 'Bungo' had significant correlation with citric acid and citric acid synthase,These results suggest that CS gene is a key gene for regulating the content of citric acid,which is a key regulator of citric acid.The'Sungold5 as a low acid fruit varieties,no find any key genes associated with the discovery in the process of analysis.The results indicated that the genes of low acid varieties need to be further excavated,and it is also shown that the metabolism of organic acids is very complicated and need to explore and analyze from many aspects.The PEPC and ME genes in the biosynthesis and degradation of malic acid in 'Yourou',The 'Bungo' and 'Sungold' is only ME genes involved in the regulation of malic acid.The results showed that the molecular mechanisms of organic acids in different species were different and the study on the expression of related genes of organic acids could lay a foundation for the further study on the regulation of organic acids from molecular aspects. |
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