Investigation of the Cu phytoremediation potential of <i>Brassica nigra</i> L. using a new <i>in vitro</i> regeneration system

The accumulation of copper (Cu) in the soil can significantly threaten the lives of plants, animals, soil microorganisms and human health. The black mustard (Brassica nigra L.) Diyarbak & imath;r ecotype is naturally and widely grown in Cu mining areas of Southeastern Anatolia. Its resistance to high Cu concentrations and strong phytoremediation capability under hydroponic conditions make this ecotype a valuable material for understanding the phytoremediation mechanism. In order to use this ecotype for phytoremediation purposes, a new tissue culture regeneration protocol is required to enable mass production. This study presents an efficient and low-cost regeneration method for the Diyarbak & imath;r ecotype. Additionally, the metallophyte properties of the regenerated plants were confirmed under both tissue culture and soil conditions. For regeneration, > 90% callus formation was achieved in all explants. While direct shoot regeneration was observed in all explants regardless of the concentration of 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP), indirect regeneration was obtained only from shoot and apex explants with NAA: BAP ratios of 1:5 and 1:4. The most efficient root formation was observed with indole-3-butyric acid (IBA) induction within 5 to 15 d (days). It was observed that there was no morphological difference in the application of 1000.0 mu M CuSO4 in tissue culture and 500.0 ppm CuSO4 in soil to regenerated plants. These results show that root tissue accumulated significantly higher levels of Cu than the other tissues in all treatments. It is proposed that B. nigra, the Diyarbak & imath;r ecotype, could be used as an ideal plant for phytoremediation.