Genotype-specific responses of six grapevine cultivars to in vitro propagation

Reliable in vitro propagation of Vitis vinifera L. is essential for large-scale clonal multiplication of disease-free planting material, the rapid multiplication of recalcitrant elite landraces, germplasm conservation and biotechnological applications. This study provides a genotype-specific optimization framework for micropropagation responses across sequential stages—surface sterilization, in vitro establishment, shoot proliferation, rooting, and acclimatization—in six grapevine cultivars (‘Rasheh’, ‘Yaghuti’, ‘Bidaneh Sefid’, ‘Bidaneh Ghermez’, ‘Turkmen 4’, and ‘Flame Seedless’). Among the tested sterilization treatments, the combined application of 1.5% silver nanoparticles (AgNPs) followed by 1.5% sodium hypochlorite (NaOCl) achieved an effective balance between contamination control and explant survival across genotypes, whereas higher AgNP concentrations resulted in mild, cultivar-dependent phytotoxic effects. Comparative assessment of eight basal culture media indicated that Woody Plant Medium (WPM) was among the most effective basal media for in vitro establishment for several cultivars, particularly ‘Rasheh’, which exhibited an establishment rate of up to 94.15% alongside improved shoot elongation and leaf development. However, other media showed comparable or superior responses for specific traits in a genotype-dependent manner. Shoot development varied significantly among cultivars, with BAP concentrations of 1.0–1.5 mg L⁻¹ generally promoting internode formation and branching, while the optimal cytokinin–auxin balance for lateral branching was genotype-dependent. For instance, the highest lateral branch number (10.01) was observed in ‘Rasheh’ at 1.5 mg L⁻¹ BAP combined with 0.05 mg L⁻¹ IBA, indicating that optimal PGR regimes vary by genotype. Root induction was achieved using combinations of low concentrations of indole-3-butyric acid (IBA; 0.01–0.05 mg L⁻¹) and benzylaminopurine (BAP; 0.5–1.5 mg L⁻¹), resulting in a maximum rooting frequency of 97.74% in ‘Bidaneh Sefid’ with 0.05 mg L⁻¹ IBA + 0.5 mg L⁻¹ BAP. Following acclimatization, regenerated plantlets showed 75–92% survival under greenhouse conditions after four weeks (Fig. 6). The findings demonstrate pronounced genotype-dependent variation throughout the micropropagation process, highlight the necessity of cultivar-specific adjustments for reliable large-scale propagation of regionally important grapevine germplasm. We emphasize that rigorous validation of long-term genetic fidelity —through molecular marker analysis or whole-genome sequencing—constitutes a critical prerequisite before commercial deployment.