Objective   Functions, identification, and copy number of As6G-FFT in the transgenic tobacco plants were studied.

  Method   PCR, qRT-PCR, and physiological analysis were performed to confirm the transgenic tobacco plants being As6G-FFT-positive and elucidate the functions of the gene. SYBR green-based qRT-PCR was applied to determine the copy number of the gene in the transgenic plant.

  Result   (1) The target fragment was amplified on the leaves of 14 tobacco plants by PCR assuring a successful transfer of As6G-FFT. (2) In varying degrees, the gene expressions in the 14 transgenic lines were higher than in the wild-type. Six of the lines were extremely significantly higher than the wild-type counterpart, with an accumulation topped 215.13-fold. (3) The fructan contents were higher in the leaves of the transgenic than the wild-type plants. Thirteen of the transgenic lines contained extremely significantly more fructan than the wild-type with the highest accumulation of 10.47-fold. (4) With correlation coefficients of 1, the SYBR green-based qRT-PCR standard curves of y=−0.2907x+3.0145 was obtained for As6G-FFT and y=−0.2813x+8.0141 for NtACT. Of the 14 transgenic lines, 35.7% contained only one of the gene, 50.0% had 2, and 14.3% 3 copies.

  Conclusion   Transgenic tobacco plants with As6G-FFT were identified based on the DNA, RNA, and physiological aspects. The SYBR green-based qRT-PCR method rapidly and efficiently determined the number of exogenous As6G-FFT transferred into the plants and could be a convenient tool for screening and acquisition of stable genetic materials.