Heat Stress Induces Partial Resistance to Tomato Bushy Stunt Virus in Nicotiana benthamiana Via Combined Stress Pathways

Global climate change is the impact of combined abiotic and biotic stresses negatively affecting plant health and productivity. This study investigated the molecular and cellular responses of <i>Nicotiana benthamiana</i> L. plants to wild-type tomato bushy stunt virus (wtTBSV) infection under conditions of pre-existing heat stress. The experiments were conducted under controlled temperature regimes of 30 °C and 37 °C in combination with virus challenge. Morphological and biochemical analyses in plants under the influence of combined stress showed the alleviation of disease symptoms, reduction in virus content and reduced expression levels of viral proteins P19 and P33. Under conditions of combined stress, accumulation of hydrogen peroxide and malondialdehyde, as well as activation of the antioxidant enzyme catalase, especially in root tissues, were observed. Notably, at 37 °C, virus infection was suppressed despite high levels of oxidative stress, whereas at 30 °C, a marked decrease in the expression of host factors was observed. The results indicate that thermal stress modulates virus-host interactions and activates defense mechanisms, including antioxidant and RNA interference pathways. Therefore, temperature adaptation can be considered as a promising strategy for enhancing plant resistance to viral pathogens under climate changes.