果实的成熟和衰老是个复杂的生物学过程,一般认为活性氧(ROS)在其中起着重要作用。本研究采用cDNA末端快速扩增技术(RACE)和RT-PCR相结合的方法,从白肉枇杷成熟期果实中成功克隆到一个编码抗坏血酸氧化酶(AO)的基因,命名为EjAO。该基因全长2 174 bp,包含了长度为1 605 bp的开放阅读框。该阅读框编码的氨基酸数目为534个,所形成的蛋白质预测分子量为59.39 kD。实时荧光定量PCR结果显示EjAO在根和果实中高丰度表达,并且在白肉枇杷成熟期果实中的表达量远远高于红肉枇杷。核苷酸多态性分析显示EjAO基因在红肉枇杷和白肉枇杷共有五处多态性位点,其中T719C和A730C均导致氨基酸发生改变,推测可能对EjAO的酶学活性产生影响。EjAO的克隆和多态性位点的鉴定为阐明枇杷果实成熟与衰老机制及枇杷遗传改良育种提供一定的理论依据。 Fruit ripening and senescence are complex biological processes, and reactive oxygen species (ROS) are generally considered to play an important role. In this study, a cDNA encoding ascorbate oxidase (AO) was successfully cloned from the mature fruit of white loquat fruit by a combination of rapid amplification of cDNA ends (RACE) and RT-PCR and named as EjAO. The gene is 2 174 bp in length and contains an open reading frame of 1 605 bp. The reading frame encodes 534 amino acids, and the predicted protein has a predicted molecular mass of 59.39 kD. Real-time PCR results showed that EjAO was expressed abundantly in roots and fruits, and the expression level of EjAO in the fruits of white loquat fruit was much higher than that of red loquat fruit. Nucleotide polymorphism analysis showed that EjAO gene had five polymorphic loci in red loquat and white loquat, of which T719C and A730C all caused amino acid changes, suggesting that EjAO may have an impact on the enzymatic activity of EjAO. EjAO cloning and polymorphism loci identification to elucidate the loquat fruit ripening and aging mechanisms and loquat genetic improvement breeding provide a theoretical basis.