Abiotic plant stress mitigation by Trichoderma species

Ascomycetes of the genus Trichoderma are beneficial fungi that promote plant growth. Several fungal species can mitigate abiotic stress in plants. Trichoderma spp. induce salt stress tolerance and drought protection in plants. Soil contamination by heavy metals can be bioremediated by Trichoderma. Trichoderma can detoxify pesticides and other pollutants in soils. Plants drive both carbon and nitrogen cycling and mediate complex biotic interactions with soil microorganisms. Climate change and the resulting temperature variations, altered precipitation, and water shortages in soils, affect the performance of plants. Negative effects of abiotic stress are reflected in changes of plant morphology associated with biochemical alterations and inadequate adaptation to rapid ecological change. Accumulation of chemical agents, derived from pesticides, salinity due to chemical fertilization, and accumulation of heavy metals, are recurrent problems in agricultural soils. Trichoderma spp. are soil fungi interacting with roots and in this way helping plants to cope with abiotic stresses by increasing root branching, shoot growth and productivity. In part, such fungal effects on the host plant are consequences of the activation of fine-tuned molecular mechanisms mediated by phytohormones, by profound biochemical changes that include production of osmolytes, by the activity of the redox-enzymatic machinery, as well by as complex processes of detoxification. Here, we summarize the most recent advances regarding the beneficial effects of Trichoderma in mitigating the negative effects on plant performance caused by different environmental and chemical factors associated with global change and agricultural practices that provoke abiotic stress. Additionally, we present new perspectives and propose further research directions in the field of Trichoderma-plant interactions when the two types of organism cooperate.