Comparative Study On The Physiological Changes And The Differences Of Fruit Sugar And Acid Content Between ’Pingguoli’ Pear And Its Large Fruit Bud

’Pingguoli’ is an important economic tree species in northern.China and has a high commercial value.Fruit size and sugar and acid content are important characteristics of ’Pingguoli’,and are also important indicators that determine the commercial quality.The mechanism has not been systematically studied on’Pingguoli’ fruit swelling and sugar and acid metabolism,and the relationship between fruit size development and sugar and acid accumulation is unclear.To this end,this study uses ordinary and large fruit bud variant ’Pingguoli’ as materials to study the two differences and correlations of components and contents of cytological characteristics,soluble sugars(fructose,sorbitol,glucose,sucrose)and organic acids(quinic acid,malic acid,shikimic acid,citric acid,succinic acid)during fruit composition and content change rule,differences and correlation.The main results are as follows:1.Detection by flow cytometry showed that the large fruit bud variant was the same as the common ’Pingguoli’ ploidy,and the mechanism of fruit enlargement was not the chromosome doubling;observed by paraffin sectioning,the cell size difference between the large fruit bud variant and the ordinary ’Pingguoli’ was not different.Significantly,the large fruit bud of ’Pingguoli’ showed an active increase in cells during the cell division and fruit maturation stages,and the number of cells was significantly higher than that of the ordinary type,which caused the fruit to increase.Observed by microscopy,the stomatal density and defense of the two,there are no significant differences in the length of the cells.The width of the guard cells of the large fruit bud variant ’Pingguoli’ is significantly higher than that of the ordinary type,and it has a tendency to become longer.2.Soluble sugar chromatography conditions:the column is CAPCELL PAK NH2 UG80 S5(4.6×250 mm,5μm);the column temperature is 35℃;the flow rate is 1.0 mL·min-1;the mobile phase is acetonitrile:82%,water:18%;ELSD detector,drift tube temperature 80℃;carrier is high purity N2,flow rate 1.0 mL·min-1;gain value 1;injection volume 5 μL.The high-performance liquid chromatography(HPLC-ELSD)was used to determine the soluble sugar components and content during the development of common and large fruit bud ’Pingguoli’.The results showed that fructose,The soluble sugar in common type and large fruit bud ’Pingguoli’ fruits are mainly fructose,glucose,sorbitol and sucrose.The content range of common ’Pingguoli’ is 0.30～4.66 mg·g-1FW、1.12～1.52 mg·g-1FW、0.32～1.17 mg·g-1FW、0～1.16 mg·g-1FW,the content range of large fruit bud variant ’Pingguoi’ is 0.52～5.30 mg·g-1FW、1.20～1.90 mg·g-1FW、0.29～1.23 mg·g-1FW、0～0.52 mg·g-1FW.The common type and its large fruit bud variant ’Pingguoli’ are mainly fructose during the fruit development stage,and the soluble sugar and total sugar content in the early growth and development are increasing,and the total sugar content of the two tends to be the same,increased with the growth and development of the fruit.Reaching the mature stage.Significant differences appeared,the sorbitol content showed a downward trend,and the glucose,sucrose and total sugar contents of common type ’Pingguoli’ fruit was significantly higher than those of the large fruit bud variants.3.Organic acid chromatography conditions:Chromatographic column is Agilent Zorbax SB-Aq(4.6 × 250 mm,5 μm);column temperature is 35℃;flow rate is 0.3 mL·min-1;mobile phase is methanol:2%,disodium hydrogen phosphate buffer Solution:98%(pH2.6);UV detector,detection wavelength 210 nm;injection volume 5 μL.The high-performance liquid chromatography(HPLC-UV)was used to determine the organic acid components and content during the development of common and large fruit bud ’Pingguoli’.The results showed that the main organic acid component in ’Pingguoli’ was quinic acid,Malic acid,shikimic acid,and citric acid,the content ranges from 0-0.906 mg·g-1FW、0.29～0.42 mg·g-1FW、0.07～0.81 mg·g-1FW、0～0.67 mg·g-1FW,the content range of the large fruit bud ’pingguoli’ is 0～0.936 mg·g-1FW、0.35～0.78mg·g-1FW、0.002～0.71 mg·g-1FW、0～0.33 mg·g-1FW.At the beginning of the growth and development of the common type and its large fruit bud ’Pingguoli’,the contents of quinic acid,shikimic acid and total acid all showed a downward trend.Both malic acid and citric acid content are on the rise during the growth and development stage.In the mature period,the total acid accumulation in the fruit increased slightly,mainly by malic acid and citric acid.At this time,there was a significant difference between the two.The malic acid content of the large fruit bud variant ’Pingguoli’ was significantly higher than that of the common Pingguoli’.At the same time,the common ’Pingguoli’ content of citric acid is significantly higher than that of large fruit bud variants,which can be divided into two types:large fruit bud variant ’Pingguoli’ dominated by malic acid and common’Pingguoli’ dominated by citric acid.4.During different developmental stages,sorbitol and total sugar content,quinic acid and malic acid content in the common ’Pingguoli’ fruit were significantly positively correlated during cell division,while sorbitol and fructose,quinic acid and total acid were significantly positively correlated with the total sugar content;sorbitol and total sugar content were significantly positively correlated with ordinary’Pingguoli’ fruits when entering the rapid growth period,and shikimic acid was significantly positively correlated with the total acid content in large fruit bud variant.At the mature stage,the fructose and total sugar contents in ’Pingguoli’ of ordinary type and its large fruit buds were extremely significantly positively correlated.