王立丰　王纪坤　安锋　谢贵水

摘 要 细胞色素b561通过参与抗坏血酸的再生在活性氧淬灭、生长发育和抗旱等生理过程中起作用。从巴西橡胶树热研7-33-97叶片中克隆一个细胞色素b561基因，其推导氨基酸含有特征性Cyt_b561家族结构域，命名为HbCytb561。该基因在花、叶片和胶乳中表达，在树皮中不表达。干旱、机械伤害和白粉菌侵染均显著上调该基因在橡胶树叶片中表达。结果说明HbCytb561基因受逆境反应诱导，参与橡胶树抗逆响应的生理和分子机制。

关键词 巴西橡胶树；干旱；细胞色素b561；活性氧；机械伤害

中图分类号 S794.1 文献标识码 A

Abstract Cytochrome b561 takes part in reactive oxygen species scavenges， growth and development as well as drought tolerance through regeneration of ascorbic acid. In this study， a HbCytb561 was cloned and designated from the leaves of rubber tree clone CATAS7-33-97， which containing specific Cyt_b561 superfamily domain. The highest expression was observed in flowers， then in leaves and latex. No expression was found in the bark. Drought， mechanical wounding and powdery mildew infection up regulated its expression at significant level. These suggested that HbCytb561， inducted by stress environment， play roles in physiological and molecular mechanisms of stress resistance in rubber tree.

Key words Hevea brasiliensis； Drought； Cytb561； ROS； Mechanical wounding

doi 10.3969/j.issn.1000-2561.2015.11.008

細胞色素b561（Cytochrome b561）家族含有b561核心结构域，根据其特征基序的不同，将其分为7个亚家族，其中B组为植物家族[1]。细胞色素b561是含有2个血红素分子的内膜蛋白，参与抗坏血酸（维生素C）再生[2]。其作用机制是作为电子传递体携带电子跨过质膜，将电子从抗坏血酸分子转移到受体分子上。抗坏血酸单电子氧化的产物-单脱氢抗坏血酸（MDHA）在哺乳动物和植物中被鉴定为是细胞色素b561的电子受体。细胞色素b561催化MDHA还原导致还原性抗坏血酸的再生。细胞色素b561在人类[3]、动物[4]和植物中都有发现，大多数物种含有3～4个细胞色素b561同源蛋白，是疏水性蛋白，含有6个跨膜结构（TMH1～TMH6）。TMH2～TMH5这4个跨膜螺旋是最保守区域，TMH1和TMH6则保守型相对较差。在植物拟南芥、葡萄、大豆和玉米等植物中发现了Cytb561基因家族成员[5]，证明其参与拟南芥抗病[6]、西瓜抗旱[7]等生理过程，其功能受到膜电势[8]、小RNA[9]和二氢硫辛酸[10]等调节。

中国橡胶树种植经常面对寒害[11]、风害和干旱[12]等逆境的威胁。……