中文摘要：

【目的】分离克隆苹果MdRCDl基因，分析其蛋白结构和逆境响应，并初步鉴定MdRCDI在苹果愈伤中的功能。【方法】同源克隆MdRCDl并测序，用DNAman和MEGA5相关软件分析MdRCDl氨基酸序列以及进化关系，不同逆境处理‘嘎拉’苹果组培苗，qRT-PCR分析MdRCDl在逆境条件下的表达量。农杆菌介导的遗传转化方法获得过量表达MdRCDl的转基因愈伤，不同盐浓度处理野生型和转基因愈伤，观察愈伤的长势，检测愈伤的鲜质量、脯氨酸和丙二醛含量，鉴定MdRCDl的初步功能。【结果】从‘嘎拉’苹果中克隆了MdRCDl（MDP0000234325）基因。该基因ORF为1803bp。通过进化树和蛋白同源性分析，表明苹果MdRCDl和中国白梨PbRCDl进化亲缘关系最近。在MdRCDl的N端有1个保守的WWE结构域，1个PARP催化中心，在C端有1个RST结构域。qRT-PCR实验表明MdRCDl在苹果各个组织器官中都有表达，在茎中的表达量高于其他组织；同时MdRCDl的表达受NaCl、ABA、渗透胁迫等逆境胁迫的诱导。通过农杆菌侵染获得过量表达MdRCDl转基因苹果愈伤。盐胁迫处理条件下，过量表达MdRCDl的抗性明显提高。【结论]MdRCDl在进化过程中比较保守，苹果不同组织中都有表达，过量表达MdRCDl苹果愈伤的抗盐性得到提高。

英文摘要：

[Objective] Plants are constantly exposed to a broad spectrum of biotic and abiotic stresses during growth and development in nature, such as salt, drought, cold and oxidation. In order to adapt to the environment, plants have developed versatile stress-response mechanisms. Recent studies have shown that SROs （SIMILAR-TO-RCD-ONE） play important roles in response to stresses in diverse spe- cies. SROs have been identified as positive regulators to protect plants from oxidation and salt damage. However, the function of SROs in woody plants remains largely unknown, particularly in apples. In this study, we isolated and cloned a SRO gene, named as MdRCD1. Furthermore, we analyzed the protein structure and expression patterns of MdRCD1, and researched the functions of MdRCD1 in apple callus. [ Methods ]The phylogenetic tree of SROs proteins were constructed using a neighbor-joining method asso- ciated with the MEGA5 program （http：//www.megasoftware.net/）. The image of the phylogenetic tree of SROs proteins was drawn in MEGA5. Homology researches of the NCBI （National Center for Biotechnolo- gy Information） databases were performed using BLAST （http：//www.ncbi.nlm.nih.gov/BLAST） with de- fault parameters. The full-length cDNA of MdRCD1 was determined by PCR. Tissue culture seedlings of ＇Gala＇ were used to clone MdRCD1 and analyze its expression levels in various stress conditions. Five years of strong ＇ Gala＇ trees were used to study the tissue expression pattern of MdRCD1 in different tis- sues. The tissue culture seedlings were grown on an Murashige and Skoog （MS） medium with 0.1 rag. L^-1 of gibberellins, 0.5 mg· L-1 of 6-Benzylaminopurine （6-BA） and 0.2 mg·L^-1 of 1-Naphthaleneacetic acid （NAA） at 25 ℃, the tissue cultures were subcuhured at monthly intervals under the long-day photoperiod （16-h-light/8-h-dark）. The ＇Orin＇ callus was grown on an MS medium containing 1.5 nag. L L2, 4-di- chlorophenoxy （2, 4-D） and 0.5 mg·L^-1 of 6-BA in the dark at 25 ℃, and