The major elements needed for plant nutrition (i.e. N, P, K, Ca and Mg contents) were analyzed in shoots of ECM and control plants exposed to the ultramafic substrate. Results are summa-
rized in Fig. 4 while full data are reported in ESM Table 4a. The presence of ECM symbiosis significantly affected major element contents in shoot tissues when compared with controls. In shoots
of A. spirorbis, significant enhancement of N content in tissues (from 33.7% to 46.5%) was observed; P assimilation was significantly enhanced from 20.3% to 57.5% (except for plants inoculated
with isolates MD09-045 and MD09-063); K assimilation was significantly enhanced from 21.4% to 35.8%; Ca assimilation was significantly enhanced from 6.1% to 18.1% (except in shoots of
plants inoculated with the isolate MD09-63) and Mg was significantly reduced by 16.6% on average (except in plants inoculated with MD09-078 and MD06-337).