Effects Of Boron On Lignin Metabolism Related Enzymes And Stone Cell Formation In Pear

There is lots of factors impact the eating quality of the pear and the stone cell is one of the crucial factors.The density and size of the stone cell play primary roles in the fruit quality of the pear while the lignin biosynthesis process directly affects the differentiation and development of the stone cell.Boron is one of the essential trace elements for the pear tree.After spraying boron fertilizer,it is found that boron not only takes part in biochemical and physiological process in the plant and influences the enzymes activity of the tissue in the cell,but also promotes cell wall formation and affects the accumulation of the stone cell.In this study,Dangshansu pear that foliage spraying by 0.1%to 0.4%of boric acid is applied as experimental material,studied the correlation of boron with stone cells and lignin content,the related enzymes activity in lignin synthetize and the enzyme genes expression pattern at the development stage of pear,in addition with the influence on the fruit quality.Moreover,we developed transgenic tomato and tobacco plants that overexpressed POD(peroxidase)and HCT(hydroxycinnamoyl transferase)genes by genetic engineering technology to check on the action of the genes,and POD,HCT subcellular localization analysis were conducted at the same time.The major conclusions were showed as follows:1.By using Dangshansu pear as the experimental material,the objective of the study is to discuss the effects of spraying boron on stone cell and lignin content,fruit quality at different fruit development stages.The results show that the content of stone cell and lignin were increased initially then decrease while the boron treatment were lower than the control at the fruit development stages;spraying boron fertilizer significantly increase the fruit weight and the vertical and horizontal stems of ripe fruit;reduce the hardness and total acid content,moreover increase the total soluble solid content of ripe fruit.By consideration of fruit quality,tree vigor and production costs,the foliage fertilization by spraying 0.3%of boron at the full-bloom stage and young pear fruit stage was the best choice.2.By using Dangshansu pear as the experimental material,the object of the paper is to analyze the effects of spraying boron on lignin biosynthesize related enzyme and antioxidant enzyme activities at different stages during fruit development.PAL(phenylalanine ammonia-lyase)and POD activities were subjected to different degrees of inhibition by spraying boron fertilizer;in addition,spraying boron fertilizer significantly boosted the activity of SOD(superoxide dismutase)and CAT(catalase)of antioxidant enzymes.3.The object of the paper is to analyze the influence of spraying boron fertilizer on the express pattern of lignin metabolism-related genes,using Dangshansu pear as the experimental material,bonded with the alteration in stone cell and lignin content at different fruit development stages.The results showed as follow:express patterns of genes varied with different genes,as well as expression patterns of different gene in the same gene family were also different during the young fruit stage(within 56 days after full bloom);overall,spraying suitable concentration of boron fertilizer inhibited the expression of different genes at different growing stages in different degree?The expression of POD-1?POD-4?HCT-2?HCT-3?HCT-4?PAL?CcoAOMT,4CL-2?Clin the previous young development of the fruit were inhibited by boron treatment,which was consistent with the change in lignin content of the fruit;but the expression of HCT-1?CAD-1?CAD-2?4CL-1?4CL-2?C4H?POD-2?POD-3 in fruit development further indicated that excess concentration of boron fertilizer promoted the express of the genes.4.In order to intensive study the gene functions of POD and HCT by using Dangshansu pear as the experimental material,the open reading frame(ORF)with restriction sites of POD and HCT were respectively obtained by PCR,and then p35S-POD-GFP and p35S-HCT-GFP were constructed respectively by fusing the GFP protein.Fluorescence microscopy was used to observe the distribution of the expression vectors in tobacco leaf epidermal cells to determine the subcellular localization of the genes.The results indicated that POD had membrane localization function while HCT was located in membrane and nucleus.5.In the study,we obtained transgenic tomato and tobacco plants that overexpressed POD and HCT to analysis the role that the genes play in lignin biosynthesis.After constructed the expression vectors pCAMBIA1301-POD/HCT,the reorganization plasmid were transformed into the tobacco and potato through agrobacterium genetic transformation method.To obtain the independent transgenic lines is significantly valuable to explore the gene function of POD/HCT in future.