Root endophytic fungus Piriformospora indica affected growth, cadmium partitioning and chlorophyll fluorescence of sunflower under cadmium toxicity.

Cadmium (Cd) pollution in the soil threatens the quality of environmental health, and deleteriously affects physiological activities of crops. Symbiosis of endophytic fungi with various plants is a promising manner to improving numerous plant characteristics and remediating heavy metal-polluted soils. In this pot experiment, the influence of root endophyte fungus Piriformospora indica on growth, physiological parameters and organs Cd accumulation in sunflower cv. Zaria plants under the toxic levels of Cd (0, 40, 80 and 120mg/kg soil) were studied. Increasing Cd concentration in the soil reduced growth parameters, chlorophyll (Chl) a and Chl b contents, and Fv/Fm and ETR (electron transport rate) values, but increased root, stem and leaf Cd accumulation, and proline content. The presence of P. indica significantly enhanced growth, Chl a, Chl b and proline contents, and Fv/Fm and ETR values. Compared to non-inoculated ones, P. indica-inoculated plants had higher Cd accumulation in root, whereas lower Cd accumulation in stem and leaf. The present study strongly supports the established ability of P. indica to alleviate Cd toxicity by improving the physiological status in sunflower. Furthermore, this endophyte fungus can be useful for Cd phyto-stabilization in sunflower roots in contaminated soils.