Abstract: Primer pairs were designed to amplify the genomic DNA of alpha-farnesene synthase gene
(AFS ) by PCR, the PCR p roductswere sequenced, the sequenceswere sp liced and compared to cDNA ( ac
cession No. AY182241) in the GenBank, then the genomic sequence and intron-exon organization of AFS
gene were obtained. The AFS genomic sequence has been registered in GenBank ( accession No.
DQ901739) , it had 6 introns and 7 exons, encoded a p rotein with 576 amino acids. The sizes of 6 introns
were 108 bp, 113 bp, > 1 000 bp, 125 bp, 220 bp and 88 bp, and their phase were 0, 1, 2, 2, 0, 0, re
spectively. The sizes of deduced amino acids of 7 exonswere 57, 89, 127, 73, 48, 83 and 99, respectively.
The AFS p rotein contained three motifs, the RR (X8) W motif was encoded by a sequence in exon 1, the
RxR motif and DDxxD motifwere encoded by two sequences in exon 4. The AFS genomic sequence ( accession
No. DQ901739) was compared to cDNA ( accession No. AY523409) in the GenBank, itwas found that there
were 6 single2nucleotide polymorphisms between the two sequences, four ofwhich causedmutations at the ami
no acid level. Interestingly, one amino acid mutation (291R→G) was found in RxR motif, it deserves further
investigation whether the alpha2farnesene synthesis ability and superficial scald suscep tibility of app leswere in
fluenced by this amino acid mutation and othermutations.

Key words: Apple, Alpha-farnesene synthase, Genomic DNA, Polymorphism, Superficial scald