A new glucosyltransferase UGT78 from Iris sanguinea is a putative negative regulator in cadmium stress response

Urbanization has resulted in a significant degra-dation of soil quality,subjecting plants to persistent abiotic stressors such as heavy metal pollution,salinization,and drought.UDP-glycosyltransferases(UGTs)participate in protein glycosylation,secondary metabolite synthesis,and detoxification of exogenous toxic substances.Iris sanguinea Donn ex Hornem exhibits a high degree of resistance to various abiotic stressors.To enhance the plant’s response to adversity,a novel glycosyltransferase belonging to the UGT78 family,encoding flavonoid 3-O-glucosyltransferase(UF3GT),was cloned from the monocot species I.san-guinea.Compared with the control group,overexpression of IsUGT78 enhanced sensitivity to cadmium stress,while showing no significant impact under NaCl and d-sorbitol treatments.Under cadmium treatment,arabidopsis exoge-nously transformed with the IsUGT78 gene possessed lower germination,fresh weight,root length,and chlorophyll con-tent and increased malondialdehyde content than the wild type arabidopsis.In addition,metabolomics in leaves led to the identification of 299 flavonoid metabolites,eight and 127 which were significantly up-and down-regulated,respec-tively,in the transgenic plants.Of note,all eight upregulated flavonoid compounds were glycosylated.Given that arabi-dopsis,which exogenously expresses the IsUGT78 gene,has reduced resistance to cadmium,IsUGT78 may lead to a reduced ability to cope with cadmium stress.

Construction of a cDNA-AFLP reaction system of Populus euphratica for abiotic stress studies

We established a cDNA-AFLP （amplified fragment length polymorphism） system for Populus euphratica, after optimizing several key factors. The results show that optimized CTAB method is suitable for the extraction of ideal RNA from P euphratica; the double-stranded cDNA （ds-cDNA） is completely digested by the combination of EcoRI and MseI for 4.5 h; the reducible result can be obtained when the preamplification products were diluted 10-fold for selective amplification templates. The amplification products resulting from this reaction system were determined by silver staining and the fragments were clear and stable. Detected by RT-PCR, the optimized differential display cDNA-AFLP technique can accurately reflect the true differences of gene expressions among plants. In addition, 42 pairs of primer arrays, producing repeatable and prolific bands, were successfully selected by this improved method. This investigation establishes a cDNA-AFLP system for P. euphratica, which forms a basis for further study on stress-response genes in P. euphratica.