Fuente: WIPO "tobacco agriculture" The invention discloses a tobacco polyphenol oxidase gene NtPPO1 and a site-directed mutagenesis method and application thereof. The nucleotide sequence of the tobacco polyphenol oxidase gene NtPPO1 is shown in SEQ ID:No.1, the coded amino acid sequence is shown in SEQ ID:No.2. The invention further discloses a clone method of the tobacco polyphenol oxidase gene NtPPO1. The clone method comprisesthe specific steps that firstly, cDNAs of tobacco leaves are synthesized; secondly, PCR amplification of the NtPPO1 gene is conducted; thirdly, a CRISPR/Cas9 carrier of the NtPPO1 gene is constructed;fourthly, sequencing detection of the NtPPO1 gene mutation is conducted. The NtPPO1 gene has a wide application prospect in preventing tobacco browning. The tobacco polyphenol oxidase gene and the encoded protein thereof provide the gene and technology support for crops especially for anti-browning breeding of tobaccos.