Differential modulation of host plant δ13C and δ18O by native and nonnative arbuscular mycorrhizal fungi in a semiarid environment
- • Native, drought-adapted arbuscular mycorrhizal fungi (AMF) often improve host-plant performance to a greater extent than nonnative AMF in dry environments. However, little is known about the physiological basis for this differential plant response.
- • Seedlings of Olea europaea and Rhamnus lycioides were inoculated with either a mixture of eight native Glomus species or with the nonnative Glomus claroideum before field transplanting in a semiarid area.
- • Inoculation with native AMF produced the greatest improvement in nutrient and water status as well as in long-term growth for both Olea and Rhamnus. Foliar δ18O measurements indicated that native AMF enhanced stomatal conductance to a greater extent than nonnative AMF in Olea and Rhamnus.δ13C data showed that intrinsic water-use efficiency in Olea was differentially stimulated by native AMF compared with nonnative AMF.
- • Our results suggest that modulation of leaf gas exchange by native, drought-adapted AMF is critical to the long-term performance of host plants in semiarid environments. δ18O can provide a time-integrated measure of the effect of mycorrhizal infection on host-plant water relations.