Enhancing Nickel Stress Tolerance in Micro-Tom Tomatoes through Biopriming with Paraburkholderia phytofirmans PsJN: Insights into Growth and Physiological Responses

Mujo Hasanović ¹ Adaleta Durmić-Pašić ¹ Erna Karalija ^2*

• ¹ Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Sarajevo, Bosnia and Herzegovina
• ² University of Sarajevo, Faculty of Science, Department for Biology, Laboratory for Plant Physiology,, Sarajevo, Bosnia and Herzegovina

Strategic utilization of symbiotic interactions between plants and rhizospheric bacteria that promote plant growth (PGP -plant growth promoting bacteria) is a sustainable approach to mitigate the effects of anthropogenic activities and the excessive Ni accumulation. Given that the specific effects of symbiotic interactions are primarily determined by the direct relationship between the characterized plant species, bacterial strain, and HMs, the main objective of this research was to investigate the effects of Paraburkholderia phytofirmans PsJN seed priming on subsequent Ni tolerance in adult Micro-Tom tomato plants (Solanum lycopersicum L.). Sterilized Micro-Tom seeds were bioprimed with P. phytofirmans PsJN for 24h, and sown into the soil. Imbibed, non-primed seeds were used as a control. After 10 days, the seedlings were transferred into Hoagland solution until the experiment was completed. The chronic and acute stresses were induced by supplementing the Hoagland solution with 10 μM and 50 μM of Ni, respectively. After Micro-Tom completed its life cycle (approx. 75 days) the number and overall weight of ripe fruits and root length revealed significant differences (p<0.05) among non-primed and bioprimed tomato plants. The concentrations of chlorophylls and carotenoids generally showed a significant difference between non-primed control and non-primed tomatoes under Ni stress which was not observed for bioprimed tomatoes. In comparison to bioprimed tomatoes treated with 50 μM of Ni, non-primed tomatoes showed statistically lower concentrations of chlorophyll a and total chlorophylls. Proline content was generally lower and more stable in bioprimed tomatoes compared to non-primed tomatoes. Bioprimed tomatoes performed better in the presence of different Ni concentrations, especially when acute stress was applied. This study suggests biopriming with P. phytofirmans PsJN improves Micro-Tom tomato resilience and development under Ni stress, making it a promising technique for improving tomato performance in Ni-contaminated environments.