The role of Gibberellic acid on some physiological responses of transgenic tobacco (Nicotiana tabacum L.) plant carrying Ri T-DNA

Transgenic and non transgenic Nicotiana tabacum L (cultivar Wisconsin) containing Ri T-DNA were treated with 0, 0.2 and 0.4 mgL-1 GA3 in Murashig and Skoog medium. Some physiological parameters including shoot length, leaf area, number of auxiliary bud, fresh and dry weight, number and length of trichomes were measured. Shoot length, fresh weight and dry weight were increased but number of trichome did not change by GA3 treatment. Chlorophyll, carotenoid and anthocyanin pigments of leaf were decreased. Auxin and gibberellic acid content of leaf and root were also measured. Exogenous GA3 increased root auxin in the transgenic plants while it did not change in shoot. GA3 treatment increased gibberellin content in both of root and shoot.