L-arginine impact on cherry rootstock rooting and biochemical characteristics in tissue culture

In the present study, the effects of indole-3-butyric acid (IBA) separately and simultaneously with L-arginine on the morphogenic and biochemical responses in the cherry rootstocks CAB-6P (Prunus cerasus L.) and Gisela 6 (Prunus cerasus × Prunus canescens) were investigated. In the CAB-6P rootstock, the best root number and root length results were obtained with 2 mg L^–1 IBA plus 0.5 mg L^–1 L-arginine and 1 mg L^–1 IBA plus 1 mg L^–1 L-arginine, respectively. The rooting percentage was highest (100%) with 2 mg L^–1 IBA alone or combined with 1 mg L^–1 L-arginine. In the Gisela 6 explants, 2 mg L^–1 IBA without L-arginine significantly enhanced root number (9.27) and root fresh and dry weight, as well as rooting percentage (100%). Root length was longest (38 mm) in the combination of the lowest IBA (0.5 mg L^–1) and highest L-arginine (2 mg L^–1) concentrations. Thus, L-arginine promotes the positive effect of IBA on rooting with regard to both root number and root length in both cherry rootstocks. In the CAB-6P explants, L-arginine combined with IBA had an inhibitory effect on leaf chlorophyll content, whereas in the Gisela 6 rootstock it had absolutely no effect. In the CAB-6P rootstock, depleted levels of proline in roots were observed, showing the osmoregulation and osmotic adjustment mechanisms. The carbohydrate concentration in leaves was greatest with 0.5 mg L^–1 IBA plus 0.5 mg L^–1 L-arginine, and in roots with 2 mg L^–1 IBA plus 0.5 mg L^–1 L-arginine. In the Gisela 6 explants, IBA (1 and 2 mg L^–1) applied both alone and along with L-arginine, as well as the combination of the lowest IBA (0.5 mg L^–1) and the highest L-arginine (2 mg L^–1) concentrations, considerably increased leaf carbohydrate concentration compared to the control. In roots, carbohydrate concentration was maximum with 2 mg L^–1 IBA plus 0.5 mg L^–1 L-arginine. The elevated levels of proline in roots with 1 mg L^–1 IBA plus 0.5 mg L^–1 L-arginine indicate stressful conditions.