Cloning and analysis of NtMYB108b gene expressed predominantly in tobacco glandular trichomes

To clarify the functions of NtMYB108 transcription factors in tobacco, a full-length cDNA sequence of MYB gene from the glandular trichomes of tobacco cv. K326 was cloned and named as NtMYB108b. The open reading frame of NtMYB108b gene was 828 bp encoding 275 amino acids. Bioinformatic predictions showed that NtMYB108b protein was located in nucleus and was a member of the S20 subgroup of R2R3-type MYB transcription factor. NtMYB108b protein had the closest relationship with Nicotiana tomentosiformis, and the sequence similarity between them reached 100.00%. Quantitative real-time PCR(qRT-PCR)analysis showed that NtMYB108b was predominantly expressed in tobacco glandular trichomes. NtMYB108b had the highest relative expression level in leaves at resettling stage. There was no significant difference in the expression levels of leaves at 5 stalk positions during flower budding stage. After ethephon(ET)or salicylic acid(SA)treatment, the expression level of NtMYB108b was significantly up-regulated, however, there was no significant change after the treatments of methyl jasmonate(MeJA), gibberellin(GA), and abscisic acid(ABA). After polyethylene glycol(PEG)simulated drought stress, the expression level of NtMYB108b was up-regulated 2 days after the treatment, which indicated that NtMYB108b might involve in the ET, SA pathway and drought stress.