Mechanism of drought stress tolerance of GF677 rootstock (peach and almond hybride) under in vitro conditions

Mechanisms of drought stress tolerance of GF677 rootstock, peach and almond hybrid, (Prunus persica × Prunus amygdalus) were studied under in vitro conditions. Plantlets of GF677 rootstock were subcultured into the Murashige and Skoog (MS) solid proliferation medium containing 1 mg/l BA (6-Benzyladenine) and 0.1 mg/l NAA (naphthaline acetic acid) in four drought stress levels 0 (control), 10, 20 and 30 g/l polyethylene glycol 6000 (corresponding to osmotic potentials 0, -0.2, -0.4 and -0.6 Mpa, respectively). After six weeks results showed that induced drought stress had a significant effect on measured parameters. By increasing drought levels in the culture medium, antioxidant enzymes activity (catalase and peroxidase), total protein content and proline content significantly increased; meanwhile soluble sugars had non-significant increasing in the different levels of drought. According to the results it can be concluded that, the most important mechanisms of drought tolerance of GF677 rootstock under in vitro conditions are the use of antioxidant defense system, increasing protein synthesis (enhancing genes expression) and proline accumulation and osmoregulation by soluble sugars had less important.