The origin of Epichloë endophyte - perennial ryegrass symbionts modify plant reactions to elevated concentration of Pb2+, Cd2+ and Cu2+ ions in soil

Abstract

Background: The phenomenon of plant mutualistic symbiosis with microbes may have a positive effect on the improvement of plant tolerance to environmental stresses. The influence of fungal endophyte of the Epichloë sp. (Clavicipitaceae) on perennial ryegrass (Lolium perenne L.) plants grown in presence of elevated concentration of heavy metal (HM) ions (Cd2+, Pb2+ and Cu2+) in soil was studied.Results: The presence of Epichloë in the host grass tissues resulted in increased accumulation of HM ions in aerial parts of plants and was dependent on host genotypes related to host plant origin. In plants with (E+) and without (E-) endophytes the hormesis effect was induced by the elevated concentration of Cu2+ ions, resulting in better growth and photosynthesis, as examined by measurements of Chl a fluorescence. The obtained results indicate that based on the laboratory evaluation of the efficiency of the symbiosis, we were able to choose the best associations of perennial ryegrass with endophytes for HM phytoremediation.Conclusions: The presence of Epichloë endophytes positively affected ryegrass ability to accumulate HM ions and this accumulation was associated with the origin of Epichloë-ryegrass symbionts.