Abstract
Stomata play a critical role in the regulation of gas exchange between the interior of the leaf and the exterior environment and are affected by environmental and endogenous stimuli. This study aimed to evaluate the effect of the arbuscular mycorrhizal (AM) fungus, Rhizophagus irregularis, on the stomatal behavior of wheat (Triticum aestivum L.) plants under combination with elevated CO2 and NaCl stress. Wheat seedlings were exposed to ambient (400 ppm) or elevated (700 ppm) CO2 concentrations and 0, 1, and 2 g kg−1 dry soil NaCl treatments for 10 weeks. AM symbiosis increased the leaf area and stomatal density (SD) of the abaxial surface. Stomatal size and the aperture of adaxial and abaxial leaf surfaces were higher in the AM than non-AM plants under elevated CO2 and salinity stress. AM plants showed higher stomatal conductance (gs) and maximum rate of gs to water vapor (gsmax) compared with non-AM plants. Moreover, leaf water potential (Ψ) was increased and carbon isotope discrimination (Δ13C) was decreased by AM colonization, and both were significantly associated with stomatal conductance. The results suggest that AM symbiosis alters stomatal morphology by changing SD and the size of the guard cells and stomatal pores, thereby improving the stomatal conductance and water relations of wheat leaves under combined elevated CO2 and salinity stress.
Highlights
Arbuscular mycorrhizal (AM) fungi belong to the monophyletic phylum Glomeromycota and form symbiotic associations with the roots of over 80% of land plant species (Smith and Read, 2008)
arbuscular mycorrhizal (AM) symbiosis has been shown to alter the stomatal behavior of the host plants (Augé et al, 2015)
The mechanisms underlying the effects of AM fungi (AMF) on stomatal traits remain largely elusive, for host plants grown under multiple environmental regimes
Summary
Arbuscular mycorrhizal (AM) fungi belong to the monophyletic phylum Glomeromycota and form symbiotic associations with the roots of over 80% of land plant species (Smith and Read, 2008). The host plants provide the fungi with photosynthetic carbon (Smith and Read, 2008). AM symbiosis has been demonstrated to affect plant performance as it leads to a series of morphological, physiological, biochemical, and molecular changes. Stomata are formed by two small symmetric guard cells on the epidermis of higher plants that play a central role in the regulation of gas exchange between the inner air space of the leaf and the outer atmosphere (Lawson, 2009). Stomata enable CO2 entry into the leaf for photosynthesis while
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