Influence of heavy metal stress on embryogenic callus tissues of Abies nordmanniana: physiological and biochemical responses

Application of heavy metals (Cr, Ni, Zn) to Abies nordmanniana callus tissue confirmed the presence of varying heavy metal resistance in in vitro breeding lines. Fir genotype G2 was clearly more resistant to abiotic stress caused by heavy metals compared to the other genotypes tested. Moreover, an effect of exposure time of fir tissues to the heavy metals was observed, including tolerance of callus to this type of abiotic stress. Amongst the heavy metals tested, Cr accumulated most extensively in the plant tissues, with a 36 % higher content than Ni, and 43.7 % higher than Zn, regardless of genotype. Changes in proteins, based on detection by SDS-PAGE, were detected under heavy metal stressing conditions. Callus, particularly of genotype G2, synthesized putative pathogenesis-related proteins (PR proteins) with mass of 10-25 kDa. The present work suggested that in vitro methods using tree callus can be used in the selection of genotypes showing varying resistance to heavy metal stresses.