[Suppression of apple polyphenol oxidase by double-stranded RNA (RNAi)].

Antisense and sense gene fragments(710 base pairs)of apple polyphenol oxidase (APPO)gene were obtained by RT-PCR amplification,using the total RNAs isolated from ripen ap- ple fruit as the template.These two fragments were ligated with a 1000bp spacer,YYT(crtW+crtY fusion)gene,which is relative to carotenoid synthesization in subcocci.The full-length 2446bp-tar- get gene was then inserted into plant binary vector pYPX145 to generate the recombinant plasmid pYF7704,which carried the expression unit of A PPO dsRNA,pYF7704 was transformed to apple (Malus×domestica)var.Red Fuji via agrobacterium tumefaciens mediated leaf disc transformation. With the selection of Karamycin and GUS detection assays,transgenic shoots of A PPO dsRNA were obtained.The results of FQ-RT-PCR indicated that A PPO mRNA level was suppressed to 91.69% in transgenic shoots compared to wide shoots.The data suggested that dsRNAi technology on apple polyphenol oxidase is feasible to be utilized in transgenic shoots.