In vitro regeneration potential of Pistacia integerrima and Pistacia khinjuk rootstocks: a modeling approach for optimal medium formulation

İngilizce (OpenAlex)

Micropropagation involves the development of whole plants from small meristematic tissues by culturing them in vitro under aseptic conditions on a nutrient medium. However, identifying a single nutrient medium suitable for propagating Pistacia, a recalcitrant species, remains challenging. While some species exhibit good growth on Murashige and Skoog (MS) medium, Pistacia species generally yield insufficient results. To address this, a five-dimensional experimental design was developed using Design- Expert software (Stat-Ease Inc., Minneapolis, MN, USA). Thirty-three experimental databases were generated by the software using the modified I-optimal criterion. MS medium served as the control treatment. A response surface model (RSM) employing simple quadratic terms was used to evaluate the relationships between factors. Significant responses were identified and visualized to highlight key factors and their interactions. In vitro growth of Pistacia species was analyzed using five factors including ammonium nitrate (NH₄NO₃), potassium nitrate (KNO₃), mesos salts (CaCl₂, KH₂PO₄, and MgSO₄), microelements (MnSO₄·4H₂O, ZnSO₄·7H₂O, H₃BO₃, KI, CuSO₄·5H₂O, Na₂MoO₄·2H₂O, CoCl₂·6H₂O), and iron (FeSO₄·7H₂O, Na₂·EDTA). The effects of these factors were assessed on several parameters, including shooting rate (%), shoot number per plantlet, number of nodes and leaves per plantlet, shoot length (cm), shoot quality, basal callus formation, hyperhydricity, and shoot tip necrosis. The results indicated that certain treatments promoted better growth and a healthier appearance compared to the MS medium. The addition of NH₄NO₃ and mesos components had a significant impact on shoot formation, shoot length, and node development. Increasing NH₄NO₃ to certain levels resulted in shoot regeneration of up to 85%, while excessive concentrations led to shoot tip necrosis. Additionally, increasing Fe and mesos levels reduced basal callus formation and enhanced tissue development. Furthermore, the hyperhydricity rate decreased with increasing KNO₃ levels, confirming the positive effect of potassium on cell stability. Overall, these findings indicate the importance of optimizing the mineral composition of the culture medium for in vitro micropropagation of Pistacia rootstocks, as it is crucial for reducing physiological disorders and enhancing regeneration success.