关键词: 小麦, Cu ²⁺胁迫, 抗坏血酸, 谷胱甘肽, 基因表达谱

Abstract: Ascorbate-glutathione (ASA-GSH) cycle plays an important role in plant response to different stresses. In this study, plants of wheat cultivar ‘Bainong 207’ was used and treated by different Cu ²⁺ concentrations (0.05、0.10、0.50、1.00 mmol·L^-1) to investigate the roles of ASA-GSH under copper stress. Physiological indexes and expression levels of four key enzymes genes in ASA-GSH cycle were determined in wheat plants. Results indicated that the parameters of growth, such as plant height, root length and fresh weight were gradually decreased with the increase of Cu ²⁺ concentration, while contents of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), ASA and GSH were increased under different Cu ²⁺ concentrations treatments. Furthermore, the expression levels of APX (ascorbate peroxidase), DHAR (dehydroascorbate reductase), MDHAR (monodehydroascorbate reductase), and GR (glutathione reductase) in ASA-GSH cycle, had been determined by quantitative real-time PCR (qPCR). Expression trends of APX were the same in leaves and roots, which  increased at Cu ²⁺ concentration of 0.05 and 0.10 mmol·L^-1 and decreased at Cu ²⁺ concentration of 0.50 and 1.00 mmol·L^-1, respectively. Expression trends of DHAR and GR were similar, which  increased at Cu2+ concentration of 0.05 and 0.10 mmol·L^-1 and decreased at 0.50 and 1.00 mmol·L^-1 in leaves; while their expression levels increased along with the increasing of Cu ²⁺ concentration in roots. Expression levels of MDHAR were similar to DHAR and GR in leaves, and similar to APX in roots. It was demonstrated that these four genes were significantly induced in roots and leaves by Cu ²⁺ stress. To sum up, ASA-GSH might play an important role in response to Cu ²⁺ stress in wheat, which was closely related to the changes of ASA and GSH contents and the differential expression of ASA-GSH cycle related enzyme genes.

Key words: wheat, Cu ²⁺ stress, ascorbate, glutathione, expression level of gene