Mycorrhizal Fungi as Bioprotectors of Crops Against Verticillium Wilt—A Hypothetical Scenario Under Changing Environmental Conditions

Abstract

The association that many crops can establish with the arbuscular mycorrhizal fungi (AMF) present in soils can enhance the resistance of the host plants against several pathogens, including Verticillium spp. The increased resistance of mycorrhizal plants is mainly due to the improved nutritional and water status of crops and to enhanced antioxidant metabolism and/or increased production of secondary metabolites in the plant tissues. However, the effectiveness of AMF in protecting their host plants against Verticillium spp. may vary depending on the environmental factors. Some environmental factors, such as the concentration of carbon dioxide in the atmosphere, the availability of soil water and the air and soil temperatures, are predicted to change drastically by the end of the century. The present paper discusses to what extent the climate change may influence the role of AMF in protecting crops against Verticillium-induced wilt, taking into account the current knowledge about the direct and indirect effects that the changing environment can exert on AMF communities in soils and on the symbiosis between crops and AMF, as well as on the development, incidence and impact of diseases caused by soil-borne pathogens.

Effects of Abiotic Stress on Soil Microbiome

“…Higher temperature also may favour the growth of new pathogenic strains at higher latitude [2]. As reported by Goicoechea [2], development of disease caused by Verticilium dahliae in olive cultivar is determined by soil temperature, where the increase in CO 2 will favour the salicylic acid pathway and suppress the jasmonate acid pathway which is essential for a stronger defence against V. dahliae attack [2]. Soil temperature also affects AMF colonization differently at different regions with different C:N ratio.…”

“…At warmer temperatures, around 30 • C, molybdenum nitrogenase is more effective due to higher affinity for N 2 compared to vanadium nitrogenase. Higher temperature also may favour the growth of new pathogenic strains at higher latitude [2]. As reported by Goicoechea [2], development of disease caused by Verticilium dahliae in olive cultivar is determined by soil temperature, where the increase in CO 2 will favour the salicylic acid pathway and suppress the jasmonate acid pathway which is essential for a stronger defence against V. dahliae attack [2].…”

“…Soil temperature also affects AMF colonization differently at different regions with different C:N ratio. Studies by Frater et al [67], show that AMF colonization increased parallel to increase temperature and pH where the experiment took place at Central United State but Goicoechea [2] mentioned that AMF colonization across the Mediterranean decreased when the temperature increased. Jerbi et al [68] agreed with Frater et al [67] where increase in temperature appears to help AMF with better root colonization by elevate plant root elongation while at colder temperature, nutrient acquisition by AMF is reduced leading to a decrease in mycorrhizal colonization.…”

“…According to IPCC [1], food prices are expected to go higher in 2050 as climate change has significant effects on crop yield through increase of CO 2, which will affect the temperature and crop productivity. For example, C3 crops received benefits from high CO 2 levels as it can increase photosynthetic rates and result in more carbohydrates and higher sugar content in crop development [2]. However, elevated CO 2 will also negatively impact plants by reducing nutritional values of crop since the increase of C/N ratio helps plants build tolerance against soil-borne pathogen, and may also trade-off on crop nutritional quality and productivity [2].…”

“…For example, C3 crops received benefits from high CO 2 levels as it can increase photosynthetic rates and result in more carbohydrates and higher sugar content in crop development [2]. However, elevated CO 2 will also negatively impact plants by reducing nutritional values of crop since the increase of C/N ratio helps plants build tolerance against soil-borne pathogen, and may also trade-off on crop nutritional quality and productivity [2]. Further, changes in precipitation patterns will affect the water availability/water level.…”