Functional Analysis Of Three UDP-glycosyltransferases Genes Under Aluminum Stress In Soybean

Al toxicity is one of the most important constraints limiting crop yield on acid soils.Cell wall is the first barrier for Al toxicity and also have capacity to accumulate more Al.The basic structure of plant cell wall and the composition of polysaccharides,such as cellulose,uronic acid,and lignin,are closely related to the occurrence of aluminum toxicity and aluminum resistance.Uridine diphosphate glucosyltransferase(UGTA)is widely present in plants and is mainly responsible for the transfer of glycosyl groups from activated donor molecules to receptors,and directly involve in the biosynthesis of polysaccharides and disaccharides.Our previous microarray analysis showed that the expression of Gm UGTAs was upregulated under Al stress.Thus,the present study aimed to clarify if composition of cell wall polysaccharides was disrupted under Al stress in soybean root apices.Three soybean genes Gm UGTA1(Glyma.13G090300),Gm UGTA2(Glyma.11G000500)and Gm UGTA3(Glyma.08G244700)were blasted from soybean genome with UGTA probe information of previous microarray.We analyze the function of three UGTA genes through bioinformatics analysis,expression pattern analysis,subcellular localization,and analysis of carbohydrates in the cell wall by overexpressing soybean hairy roots.The main findings are as follows.1.Using quantitative real-time PCR experiments,it was found that Gm UGTA1(Glyma.13G090300),Gm UGTA2(Glyma.11G000500)and Gm UGTA3(Glyma.08G244700)genes was verified to upregualted under Al stress in soybean root apices.The transcription abundance increased about 3 folds within 4 h Al treatement duration.The expression of Gm UGTA2 and Gm UGTA3 increased from 12 hours,the former was 18 folds and the latter reached27 folds at 24 h treatmentduration.2.The plant expression vector p EGAD-3XHA-LUC carrying each UGTA gene was transformed into soybean hairy root using Agrobacterium rhizogenes K599.LC-MS metabolomics preliminary analysis showed that xylose,glucose and other sugars changed greatly in the Gm UGTA1-OE hairy roots compared with the WT.The concentrations of cell wall polysaccharides,xylose,lignin,and glucose were compared within three transgenic Gm UGTAs-OE lines and WT.The results show thatunder the condition of non-aluminum treatment,the contents of cell wall polysaccharide,callose and xylose of Gm UGTA1-OE and Gm UGTA2-OE changed significantly,the content of lignin did not change significantly,and the content of glucose decreased significantly compared with the wild type;Contents of cell wall polysaccharides and calloses of the Gm UGTA3-OE were significantly changed,but compared with WT hair roots,the xylose and glucose contents were significantly decreased,and the lignin content was not significantly changed.Under the aluminum treatment conditions,the content of Gm UGTA1-OE and Gm UGTA3-OE cell wall polysaccharides and calloses were further increased,xylose and lignin contents were not changed significantly,but the glucose contents were significantly lower than that of the wild types;the cell wall content of the polysaccharide,callose,xylose and lignin of the Gm UGTA2-OE were changed little,but the glucose contents were decreased significantly compared with the wild type.