关键词: 草莓, 单脱氢抗坏血酸还原酶, 谷胱甘肽还原酶, 克隆, 序列分析, 表达分析

Abstract: In order to furtherly investigate the function of monodehydroascorbate reductase（MDHAR）and glutathione reductase（GR），their cDNA sequences have been identified from strawberry（Fragaria × ananassa‘Toyonaka’）using homology cloning method. The full length of FaMDHAR cDNA is 1 305 bp，it encodes a putative protein consisted of 434 amino acids，which contains a conserved FAD binding domain. The subcellular location of this peptide is in cytoplasmic. The fragment of FaGR cDNA contains an open reading frame（ORF）of 1 491 bp，encoding a putative protein（496 amino acids，its molecular weight is 53 kD）. It is also predicted to localize in cytoplasmic. The results of real-time quantitative PCR showed that，among different tissues the highest relative expression level of FaMDHARwas detected in ripe fruits，the lowest expression level was detected in root. Whereas，FaGR expressed higher in leaves and flowers compared to the expression level in ripe fruits. What’s more，the FaMDHAR expressed in green fruits and it increased dramatically up to the white stage where it showed the highest level，thereafter it decreased and stayed at a constantly level during the later ripening stages. Also，during the fruit development and ripening，FaGR showed a substantial increasing from the green fruits up to the turning stage where the highest expression was detected，thereafter it decreased and expressed lower in the ripe fruits compared to the earlier stages. And these two enzyme activities changed during fruit development and ripening，which showed similar trend with their expression pattern respectively. Furthermore，under 4 ℃ low temperature stress the relative expression level of FaMDHAR in leaves significantly increased compare to the control；In contrast，the relative expression level of FaGR showed no significant change. The results indicate that the FaMDHAR and FaGR express differently in different tissues and developmental stages，and under low temperature stress.

Key words: strawberry, monodehydroascorbate reductase, glutathione reductase, cloning, sequence analysis, expression analysis