cDNA-AFLP Analysis of Differentially Expressed Genes in Tobacco Infected by Tobacco Mosaic Virus

Longjiang 925 is a flue-cured tobacco variety with high resistance to Tobacco mosaic virus (TMV). In this study, the cDNA extracted from the TMV-inoculated leaves of Longjiang 925 was amplified with 240 pairs of primers. Approximately 9500 gene transcript fragments were obtained, in which 12 inducible expressed gene fragments were selected by cloning and sequencing. The inducible fragments functions involved in the nucleic acid metabolism, protein synthesis and modulation, energy metabolism, stress responding, intracellular transport, and metabolism of carbohydrates. The function of a differentially expressed gene sequence, TIF2, was validated using real-time PCR with the samples collected at 0, 12, 24, 48, and 72 h post inoculation. The result indicated that TIF2 was related to TMV-resistance. Both 5′- and 3′-rapid amplification of cDNA ends (RACE) were preformed using TIF2 sequence, and the full-length cDNA sequence was 875 bp in length, containing a conjecturable coding region from 101 bp to 613 bp and encoding 170 amino acids. Analyses of Blastn and Blastp showed that this gene was probably a novel gene related to TMV resistance in tobacco.