Effects Of Gibberellin And Ethephon On Fruit Development Of Rabbiteye Blueberry

Blueberriy(Vaccinium ssp.)is a plant of the genus Vaccinium of the azalea family(Ericaceae).Because of its health benefits,it has become one of the tree species which develop rapidly in recent years.Rabbiteye blueberry is widely planted in China due to its strong soil adaptability and high yield.In this experiment,'Baldwin' and 'Brightwell' were used as material,gibberellin and ethephon were applied at different stages(pre-flowering and veraison).By determining the growth curve of rabbiteye blueberry fruits,the activities of PG and Cs,the content of reactive oxygen species and malondialdehyde(MDA),the permeability of cell membrane,the activities of antioxidases in abscission zone.The main results are as follows:1.Spraying gibberellin before flowering promoted the development of rabbiteye blueberry fruits.Treatment of 100 mg/L gibberellin increased the single fruit weight,vertical and horizontal diameter of rabbiteye blueberry fruits.The single fruit weight in the fifth section was increased by 19.3%,which was greater than that in the second section.2.Both 'Baldwin' and 'Brightwell' fruits are covered with white rod-shaped wax;the stomata are filled with wax.The wax structure of 'Baldwin' is relatively slender,the edges of stomata are clear The wax structure of `Brightwell' is more densely clustered,and the edges of stomata are covered by wax.During the veraison,treatment of 200 mg/L gibberellin,500 mg/L ethephon and water had no significant effect on the wax structure and the stomata shape.3.With the maturity of the rabbiteye blueberry fruit,the number of layers of the epidermis cells outside the 'Brightwell' carpopodium increases,the volume of the thin-walled cells increases,the phloem and xylem thicken,the staining of phloem and xylem are deepens,and the cell volume of the medulla increases.The separation layer has been formed before the treatment.After 28 days with ethephon treatment,the division of delaminated cells extended to the phloem,but there was no significant difference in gibberellin treatment.4.As the development of rabbiteye blueberry fruits,the content of ROS and MDA accumulated,and the permeability of cell membrane increased;the activities of PG and cellulose Cs enzymes increased.Treatment of 200 mg/L gibberellin,inhibited the increase of the activity of the two enzymes,inhibited the accumulation of reactive oxygen species and MDA content,reduced the permeability of the cell membrane,and improved the activity of antioxidant enzyme,while the treatment of 500 mg/L ethephon was contrary.5.After spraying 100 mg/L gibberellin and 500 mg/L ethephon during the veraison.In total,157.04 Gb clean data were generated from transcriptome sequencing of'Brightwell' and 'Baldwin',and the total number of unigene on 8 functional databases(NR,NT,KO,swiss-prot,Pfam,GO,KOG,eggNOG4.5)was 51193.Through GO classification and KEGG Pathway enrichment analysis,unigene was classified into 52 GO categories and 129 metabolic pathways,respectively.Analysis of gene differential expression showed that,in 'Baldwin',comparasion of gene expression in gibberellin treatment with the control group after 24 h,there were 19 genes up-regulated and 9 genes down-regulated,while there were 1361 genes up-regulated and 1133 genes down-regulated of treatment of ethephon;in 'Brightwell',comparasion of gene expression in gibberellin treatment with the control group after 24 h,there were 22 genes up-regulated and 99 genes down-regulated,while there were 900 genes up-regulated and 691 genes down-regulated of treatment of ethephon.There were 498 common genes in the differential genes after 24 h treatment of ethephon in 'Baldewin' and'Brightwell'.Five differential genes related to cell wall degradation were screened out in 'Brightwell'and four differential genes were screened out in 'Baldwin'.