Cadmium (Cd) is one of the toxic heavy metals not essential for the growth and development of plants and other organisms. Brassica rapa accumulates several heavy metals in its leaves and is reportedly suitable for phytoremediation. In this study, Cd uptake and accumulation in the leaves of B. rapa exposed to different cadmium levels (0, 5, 10, 20, 50, 100 μM CdSO4) were analyzed, as well as the effect of Cd stress on HMA2 and HMA4 genes expression were investigated. The qRT-PCR results showed that HMA2 and HMA4 play a vital role in cadmium uptake and translocation in B. rapa at low Cd levels (5-20 μM). However, exposure to high Cd levels (50 and 100 μM) significantly reduced the growth and biomass of B. rapa. Furthermore, high levels of Cd inhibit the expression of HMA2 and HMA4 genes in B. rapa. Our data show a multigenetic (co-acting of many transporter gene clusters) response in the signaling pathway associated with Cd accumulation and tolerance mechanism in B. rapa.

Bu araştırmada Sivas ve yöresinde bulunan 5 süt fabrikasının depo tankından temin edilen 50 adet süt örneğinde ağır metallerden kadmiyum (Cd), bakır (Cu), krom (Cr) ve kurşun (Pb) içerikleri incelenmiştir. Araştırma sonucunda süt örneklerinin Cd, Cu ve Cr içeriklerinin sırasıyla 8,896, 33,69 ve 31,81 µg/kg düzeyinde olduğu saptanmıştır. Süt örneklerin %92’inde Pb miktarının tespit edilebilir limitin altında, %8’inde ise 304,1-503,4 µg/kg olduğu belirlenmiştir.

In this study was carried out to determine the effects of humic acid in heavy metal stress of lettuce changes in some of the morphological and physiological characteristics. In studies conducted in controlled greenhouse conditions, lettuce plants subjected to four different 4 different humic acid levels humic acid doses (0, 2, 4, 8 L/da) and 4 different heavy metal irrigation levels (Control: 0 ppm; I. mixture: 0.2 ppm Cu + 0.01 ppm Cd + 5 ppm Pb + 2 ppm Zn; II. mixture: : 0.4 ppm Cu + 0.02 ppm Cd + 10 ppm Pb + 4 ppm Zn; III. mixture: 0.8 ppm Cu + 0.04 ppm Cd + 20 ppm Pb + 8 ppm Zn). Four weeks after at heavy metal and humic acid treatment young plants were harvested and the shoot fresh and dry weight, root fresh and dry weight, shoot and root length, and leaf areas, MDA, superoxyde dismutase (SOD) and glutathione reductase (GR) were determined. The most highly toxic effects were determinate III. mixture level (0.8 ppm Cu + 0.04 ppm Cd + 20 ppm Pb + 8 ppm Zn). MDA and antioxidative enzyme activities increased in plants irrigated with water containing a mixture of heavy metal. Humic acid applications had a positive effect on reducing of the limiting effect of heavy metal stress on growth and development.