Evaluation of hormone content in transgenic rose (Rosa hybrida L.) with etr1-1 gene treated by ethylene and gibberellin

Roses are one of the most important cut flowers in the world and therefore many studies have focused on keeping post-harvest quality and longevity. Ethylene is one of the major factors that limits post-harvest longevity. Therefore, genetic manipulation has been considered to reduce the adverse effects of this hormone and the present research investigates transgenic roses containing the mutant etr1-1 gene. In addition, according to antagonist effects, the change of gibberellin concentration to ethylene in favor of higher gibberellin concentration in the present research has been studied.

The content of phytohormones in long-lasting line (transgenic) and control (non-transgenic) after application of ethylene (0 and 1 µL L-1) and gibberellin (80 mg L-1) treatments were investigated in bud and half-open stages. Application of ethylene treatment was performed by injecting pure gas into polyethylene bags by syringe. For the application of gibberellin treatment, cut flowers were placed in gibberellin solution at the desired concentration. The treatments were applied for 24 hours and samples were taken from the outermost ring of petals. Experiments were conducted as factorial in a completely randomized design with four replications in order to measure phytohormones.

The results showed a decrease in the amount of gibberellin, benzyl adenine and indole acetic acid hormones and an increase in the amount of abscisic acid and ethylene hormones in bud and half-open stages in long-lasting line were significant compared to the control. In addition, the highest content of gibberellin, indole acetic acid and benzyl adenine hormones and the lowest content of ethylene and abscisic acid belongs to the GA3-treated long-lasting line.

Therefore, etr1-1 gene appears to be the right candidate for delaying ethylene-dependent aging in sensitive flowers and with GA3 treatment could be considerably improved longevity by reduction of oxidative damage.