Cell and Tissue Journal

Abstract Aim: Potato (Solanum tuberosum L.) is a key crop within the Solanaceae family and ranks as the most significant non-cereal crop globally following major staples such as wheat, rice, and corn. Potatoes can reproduce sexually and asexually via tubers, and plant tissue culture is emerging as an effective method for vegetative propagation, addressing the increasing global demand for agricultural products. Ethylene, a critical plant growth regulator, influences various physiological processes including growth and development. During in vitro culture and due to the wounding of explants, ethylene accumulation can lead to abnormal biological responses, with potato seedlings being susceptible. Thus, investigating the effects of ethylene biosynthesis inhibitors such as pyrazinamide (PZA) and AgNO₃ on potato growth in vitro is essential.
Material and Methods: In this study, potato seedlings were cultivated in Murashige and Skoog (MS) medium, with concentrations of PZA ranging from 0 to 6 mg L⁻¹ and AgNO₃ at 2 mg L⁻¹. After four weeks, the seedlings were harvested and stored at -70°C for later analysis. The growth parameters measured included fresh weight (FW), dry weight (DW), stem and root lengths, leaf area, and leaf and root number. In addition, biochemical parameters, such as photosynthetic pigment levels, total phenol content (TPC), total reactive oxygen species (ROS), and proline concentration were analyzed. Statistical evaluations were conducted using SPSS and PAST software
Results: The results showed that the 2 mg L⁻¹ PZA treatment led to the highest FW and DW and increased leaf numbers; however, it was also correlated with a lower number of rooted plants. Conversely, treatments with 6 mg L⁻¹ PZA promoted longer stem growth, whereas control plants exhibited the largest leaf area, and AgNO₃-treated plants produced the longest roots. The accumulation of H₂O₂ in plants treated with ethylene inhibitors was like controls, but total ROS levels soared by 36% in those treated with 6 mg L⁻¹ PZA compared to controls. This suggests a link between reduced ethylene production, oxidative stress mitigation, and enhanced potato growth. Additionally, total ROS was positively correlated with stem length, but negatively correlated with root length.
Plants use several strategies to combat the damaging effects of ROS, such as the production of antioxidant compounds such as phenolics. Although PZA did not significantly alter TPC compared to controls, treatment with AgNO₃ caused a 61% reduction in TPC. Therefore, PZA did not appear to significantly affect phenolics production in the potato seedlings.
Proline, another critical antioxidant in plants, was found to accumulate significantly in the leaves of plants treated with 6 mg L⁻¹ PZA, which was more than 2.3 times higher than that in controls. This accumulation correlated positively with ROS levels at higher PZA concentrations but showed an inverse relationship with photosynthetic pigment levels.
The PCA revealed the relationships between the measured parameters and the applied elicitors. The samples were categorized into four distinct groups:

Control group: This group primarily exhibited higher FW, DW, and longer roots compared to the treated plants.
Low PZA dose group: These plants displayed elevated levels of photosynthetic pigments, TPC, and leaf area.
Medium PZA dose group: Correlations were observed with an increased number of roots.
6 mg L⁻¹ PZA and AgNO₃ group: These samples contained elevated levels of total ROS and proline.

Conclusion: The study concludes that low concentrations of PZA can stimulate growth while inhibiting ethylene production, resulting in fewer growth abnormalities compared to control plants. However, at elevated PZA concentrations, increased ROS levels may lead to oxidative stress, emphasizing the delicate balance in ethylene's role in plant growth and the necessity for further research to optimize conditions for potato cultivation in vitro. The findings contribute to a deeper understanding of how ethylene inhibitors can enhance potato propagation and possibly other crops in controlled agricultural environments.

Abstract Aim: Ethylene, a phytohormone, is produced during in vitro plant tissue culture and its accumulation is associated with reduction of growth and morphological changes. The aim of this study was to evaluate application of CoCl₂, as ethylene synthesis inhibitor, on growth and some physiological parameters as well as expression of ACC oxidase gene of potato.
Material and Methods: In this study, nodal segments of potato (Solanum tuberosum L.) cv. White Desiree were cultured on MS medium containing concentration of 0, 5, 10, 15, 20, 30, 40, 60 mg/L CoCl₂. After 5 weeks, chlorophyll a,b, total, cartenoied, content, leaf area and expression level of ACC oxidase gene were investigated.
Results: CoCl₂ inhibited root production in aerial parts and increased leaf areas and amount of chlorophyll a,b and carotenoid. Application of 20 mg/L CoCl₂ was the best for potato growth. ACC oxidase gene expression was decreased at this concentration.
Conclusion: Application of CoCl₂ decreased ACC oxidase gene expression and prevented ethylene accumulation in the in vitro culture and consequently improved growth of potato plant.