Effect of the culture liquid of Antarctic yeast <i>Nadsoniella nigra</i> on rooting, growth, and biochemical composition of <i>in vitro</i> grapevine (<i>Vitis vinifera</i> L.), cultivar '<i>Karmrahyut</i>'

Abstract

Background: Grapevine (Vitis vinifera L.) is a globally significant fruit crop known for its nutritional and health benefits, including its role in preventing chronic diseases such as cancer and cardiovascular disorders. The bioactive compounds in grapes contribute to these benefits. Bioactive content changes due to grapevine variety and environmental conditions necessitate ongoing research. In vitro propagation provides a controlled environment for grapevine cultivation, minimizing disease risk and ensuring consistent quality. This study investigates the potential of Nadsoniella nigra (Nn), an Antarctic yeast, as a natural alternative to synthetic auxins like Indole-3-butyric acid (IBA) in grapevine micro cutting propagation. Objective: To evaluate the effectiveness of the culture liquid of Nn as a natural alternative to auxin-class hormones, using IBA as an example, for promoting rooting in grapevine microcuttings and to assess its impact on chlorophyll content, vitamin C levels, and sugar concentrations. Materials and Methods: In vitro propagation of grapevine (Vitis vinifera L.) cultivar 'Karmarhyt' was performed using half-strength Woody Plant Medium (WPM). Nn culture liquid was prepared at concentrations of 0.5, 1.0, 1.5, and 2.0 ml/L, and IBA was used at equivalent concentrations. Microcuttings were cultured on media supplemented with these treatments, with a control group maintained without growth regulators. Rooting was evaluated after 4 weeks by measuring rooting percentage, number of roots per shoot, and root length. Chlorophyll a (Chl a) and Chlorophyll b (Chl b) levels, vitamin C content, and sugar concentrations were assessed. Statistical analysis was performed using standard error and t-tests. Results: Rooting performance of grapevine microcuttings varied with treatment. Nn culture liquid promoted rooting in a dose-dependent manner, with the highest values observed at 2.0 ml/L (97.0% rooting, 7.2 roots, 13.8 cm root length). IBA treatment resulted in peak rooting at 1.0 mg/L (100% rooting) but decreased at higher concentrations, accompanied by callus formation. Chlorophyll content was higher in Nn culture liquid treated microcuttings, with a maximum total chlorophyll of 2.20 mg/g at 2.0 mg/L, compared to a peak of 2.05 mg/g in IBA-treated microcuttings at 1.0 mg/L. Sugar and vitamin C content increased with Nn culture liquid concentrations, whereas IBA showed a less consistent effect. Conclusion: Nn culture liquid was an effective natural alternative to IBA for promoting rooting in grapevine microcuttings. It improved rooting efficiency, chlorophyll content, and increased sugar and vitamin C levels, while IBA led to growth inhibition and callus formation at higher concentrations. Nn culture liquid demonstrated consistent benefits, suggesting potential for sustainable viticulture. As a result of the conducted research, it was established that the mixture of secondary metabolites contained in the liquid culture medium of Nn possesses high biological activity and can be recommended for use in plant biotechnology in vitro to promote the growth of both underground and above-ground parts. Future research could explore its use in propagating other plant species. Keywords: ´Karmrahyut´, grapevine, culture liquid of Nadsoniella nigra. in vitro propagation, functional foods