Effect Of Bagging On Apple Fruit Coloring And The Expression Of Related Genes

Fruit color is the key factor of visual quality,which also affects the economic value of apple fruit.The skin color is determined by its genetic cues,and the environment cues also responses to the outer color.Fruit bagging as an important cultivation measure can change the micro-environemnt for fruit growth,and improve the external quality of fruits significantly,while,the mechanism of coloration is still unclear.So in my experiment,we chose ‘Golden delicious',‘Qinguan',‘Royal gala',‘Yuhuazaofu',‘Changfu-2',‘Qinguan',and ‘Cripps pink' which were all planting at Loess plateau,and removed bags at different times during the mid-late stages of fruit development,to analysis the changes of fruit color,and the relationships among sugars,organic acids,and the the related genes of anthocyanin biosynthesis,to explore the red skin characteristics,and the effect of the removing bags times on apple coloration mechanism,lay the foundation for improving the fruit external qualities by genetic breeding and cultivation measurements.The major results were as follows:1.During the mid to late period of fruit development,‘Golden delicious' and ‘Qinguan' fruit were moved bags every two weeks,and detected the external color changes,pigment content in apple skin,and content of sugars and organic acids in pulp.The result was indicated that,the red cultivar ‘Qinguan' was removed bags before 176 DAF(176 days of after flower),there had smaller changes of fruit color than that of fruit with removing bags after the day,and color index a* values were kept negative,anthocyanin accumulation was increased slowly,the content was kept about 150 ?g mg-1FW,after that day,a* were increased to positive values,and anthocyanin accumulation was increased sharply;anthocyanin accumulation was less in the bagging treatment than that in no-bagging fruit.In ‘Golden delicious';although,removing bags were conducted at different time of the mid to late period of fruit development,a* values were always kept negative,and there had only trance of anthocyanin accumulation.And bagged fruit reduced the content of chlorophyll and carotenoid in both ‘Golden delicious' and ‘Qinguan' skin.Further study was showed that the effects of bagging treatments on anthocyanin,chlorophyll and carotenoid content in the four different maturity time of red apple cultivars,‘Royal gala',‘Yuhuazaofu',‘Changfu-2',and ‘Cripps pink' were similar to that of ‘Qinguan'.The results indicated that,rapid anthocyanin accumulation occurred in apple peel at a specific time,and was unaltered by debagging time in the red cultivar,there had howed less effect of removing bags on fruit coloring before the specific time,but the time of removing bags can affect anthocyanin content when the fruit was harvest.2.we detected sugars and acids during the mid to late period of fruit development,the total sugars,founding that bagging treatment decreased fructose,glucose sorbitol,malic acid the total sugars and acids contents,and the later of removing bags time was,the bigger of falling range of the four materials;whereas it improved glucose and citric acid content in fruit.However,there had on liner relationship between the removing bags time and the two materials.And there had the most striking difference between bagging(T7)and no-bagging(Control)treatment was at the harvest time.In ‘Golden delicious' fruits,total sugars,total acids,glucose and citric acid content was 111.65/130.54 mg g-1 FW,5.32/6.16 mg g-1 FW(T7/Control,159 DAF),24.35/22.23 mg g-1 FW and 0.0659/0.0508 mg g-1 FW,respectively;the content of these materials in ‘Qinguan' fruits were 102.71/117.34 mg g-1 FW,8.52/10.49 mg g-1 FW,38.81/33.53 mg g-1 FW,and 0.0602/0.0416 mg g-1 FW(T7/Control,196 DAF),respectively.The two cultivars exhibited the similar change feature in sugars and organic acids.3.The correlation analysis results was showed that there had positive correlation between sucrose and anthocyanin in the five cultivars during the mid-late period of fruit development,while there had the lack correlation between fructose,glucose,sorbitol,malic acid,citric acid and anthocyanin,and the relations was not stable in the five cultivars.The starch content as the indicator of the maturity when the fruits were ripe,the relationship among starch,sucrose,glucose was showed negatively correlation.While the correlation between anthocyanin and starch was stable in ‘Royal gala',‘Yuhuazaofu' and ‘Cripps pink',and this relation ‘Changfu-2' and ‘Qinguan' was not significant.4.We detected the activity of the relative enzymes in the path of anthocyanin biosynthesis of both ‘Qinguan' and ‘Cripps pink',the results were showed that bagging treatment reduced enzyme activity of CHI,DFR and UFGT.The CHI and UFGT enzymes activity were increasing with the fruit development,while,DFR enzymes activity were not changed.the structural gene MdCHI,MdF3 H,MdDFR,MdUFGT,and the regulated genes MdMYB1,MdMYB10,MdbHLH3 and MdbHLH33 was reduced by a large margin in bagging treatments.The results of relative expression analysis were showed that bagging treatment reduced the expression lever of sucrose transferase SUT1 in the skin of red cultivars significantly,and the largest reduction range was occurred at 191 DAF.