Ectomycorrhizal inoculation with Pisolithus tinctorius reduces stress induced by drought in cork oak

Abstract

We investigated whether the performance of cork oak under drought could be improved by colonization with the ectomycorrhizal fungus Pisolithus tinctorius. Results show that inoculation alone had a positive effect on plant height, shoot biomass, shoot basal diameter, and root growth. Under drought, root growth of mycorrhizal plants was significantly increased showing that inoculation was effective in increasing tolerance to drought. In accordance, mycorrhizal plants subjected to drought showed less symptoms of stress when compared to non-mycorrhizal plants, such as lower concentration of soluble sugars and starch, increased ability to maintain fatty acid content and composition, and increased unsaturation level of membrane lipids. After testing some of the mechanisms suggested to contribute to the enhanced tolerance of mycorrhizal plants to drought, we could not find any by which Pisolithus tinctorius could benefit cork oak, at least under the drought conditions imposed in our experiment. Inoculation did not increase photosynthesis under drought, suggesting no effect in sustaining stomatal opening at low soil water content. Similarly, plant water status was not affected by inoculation suggesting that P. tinctorius does not contribute to an increased plant water uptake during drought. Inoculation did increase nitrogen concentration in plants but it was independent of the water status. Furthermore, no significant mycorrhizal effect on drought-induced ROS production or osmotic adjustment was detected, suggesting that these factors are not important for the improved drought tolerance triggered by P. tinctorius.

Microbial Diversity of Upland Rice Roots and Their Influence on Rice Growth and Drought Tolerance

“…Physiological parameters such as antioxidant enzyme (POD, SOD, CAT) activity, Pro content, MDA content and plant soluble sugar content are closely involved in the drought response [ 24 , 36 ]. ROS, whose production is a typical plant defense response, are usually strongly associated with abiotic stress.…”

“…Another group of microbes, mycorrhizal fungi, promote the metabolism and development of plants by facilitating plant water uptake via their extensive hyphae [ 33 , 34 ]. Furthermore, PGPB and PGPF (include mycorrhizal fungi) can increase plant stress tolerance by inducing the accumulation of osmolytes [ 35 ] and antioxidants [ 24 , 36 ], regulating stress response genes [ 37 , 38 ], increasing mineral nutrition and photosynthesis, and altering root morphology [ 39 ].…”

Emergy evaluation for decision-making in complex multifunctional farming systems

“…Moreover, montado biodiversity is more than an existence value, being critical to maintain the functional balance between all the components of the system, particularly those related with soil. For example, ectomycorrhizal fungi are key components for the functioning and long-term persistence of montados (Reis et al, 2018), through establishing symbiotic relationships with tree roots that allows increasing tree survival and growth rate (Dinis et al, 2016), protecting plant from soil pathogens (Corcobado et al, 2014), improving drought resistance (Sebastiana et al, 2018), and providing nutrients (Sebastiana et al, 2017).…”

Genetically determined fungal pathogen tolerance and soil variation influence ectomycorrhizal traits of loblolly pine

“…This observation may seem to run counter to our general understanding that association with mycorrhizal fungi increases plant fitness, most often indicated by a growth metric. However, the nuances of the symbiosis are revealed by studies on the importance of context-dependency (e.g., Hoeksema et al, 2010), and other fitness benefits such as drought tolerance (Sebastiana et al, 2018); as such, growth benefits in short-term experiments may not always be expected, even in symbioses that are beneficial in situ.…”

“…Mycorrhizal fungi are common symbionts of most plants, deriving mineral nutrients from the soil and transferring them to the host, while the host provides carbohydrates to the fungi. Mycorrhizal fungi also have been shown to affect essential host traits such as drought tolerance, and to alter competitive interactions within and among plant species (Bennet & Cahill, 2016;Gehring, Sthultz, Flores-Renteria, Whipple, & Whitham, 2017;Sebastiana et al, 2018;Smith & Read, 2008). It has been estimated that from 6,000 (Brundrett, 2002) to as many as 20,000 (Rinaldi, Comandini, & Kuyper, 2008) different species of fungi form a particular type of mycorrhizae, ectomycorrhizae (EM).…”