The Effect of Long-Term Cd and Ni Exposure on Seed Endophytes of <i>Agrostis capillaris</i> and Their Potential Application in Phytoremediation of Metal-Contaminated Soils

<div><p>We examined whether long-term Cd exposure leads to beneficial changes in the cultivable endophytic bacteria present in the seeds of <i>Agrostis capillaris</i>. Therefore the cultivable seed endophytes of <i>Agrostis capillaris</i> growing on a long-term Cd/Ni-contaminated plot (Cd/Ni seeds) were compared with those originating from a non-contaminated plot (control seeds). We observed plant- and contaminant-dependent effects on the population composition between control and Cd/Ni seeds. Also differences in phenotypic characteristics were found: endophytes from Cd/Ni seeds exhibited more ACC deaminase activity and production of siderophores and IAA, while endophytes from control seeds, very surprisingly, showed more metal tolerance.</p> <p>Finally, the 3 most promising seed endophytes were selected based on their metal tolerance and plant growth promoting potential, and inoculated in <i>Agrostis capillaris</i> seedlings. In case of non-exposed plants, inoculation resulted in a significantly improved plant growth; after inoculation of Cd-exposed plants an increased Cd uptake was achieved without affecting plant growth. This indicates that inoculation of <i>Agrostis</i> with its seed endophytes might be beneficial for its establishment during phytoextraction and phytostabilisation of Cd-contaminated soils.</p> </div>