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.