Trichoderma asperellum Enhances Low-Temperature Tolerance of Tomato Plants by Regulating Oxidative Stress, Osmolyte Accumulation, and Stomatal Traits

Low temperature is one of the major environmental challenges for most crops, especially those of tropical and semitropical origin. The present work aimed to study low-temperature tolerance in tomato plants when these were previously inoculated with a Trichoderma asperellum strain. Here, it was demonstrated that tomato plants inoculated with the bioinoculant exhibited an alleviation of the injuries caused by low temperatures, with a 2.2-fold increase in plant survival. The increase in chilling tolerance was accompanied by a strong reduction in oxidative stress, but also by enhancements in proline and soluble sugar accumulation of at least 1.7-fold. Additionally, leaf stoma features were also measured, and it was found that both the bioinoculant and low temperatures increased leaf stomatal densities by 32% and 29%, respectively, and raised the stomatal index, while reducing stomatal area by 25–30%, suggesting that leaf traits may also contribute to alleviating the damage caused by low temperatures in tomato plants. The results of the present study demonstrate that T. asperellum provokes physiological and biochemical changes in tomato plants that together enhance tolerance to low temperature, leading us to propose the use of T. asperellum as an agroecological strategy to combat crop damage under low temperatures.