Expression of metal transporting of genes (HMA1 and HMA3) and metabolic some changes Brassica juncea and Brassica nigra grown at different copper (Cu) levels

This study was carried out to analyse the Cu induced gene expression in accumulator plant B. nigra L. (black mustard) and tolerant plant B. juncea L. (brown mustard). In this connection, the gene expression pattern of metal ATPases (HMA1, HMA3) were investigated in both plant species grown at different Cu levels (0,25,50,100,200,500,1000 µM). Cu accumulation in root and leaves of these plants were detected using Atomic Absorption Spectrophotometer (AAS). HMA1 and HMA3 expression levels in the leaves of both plant species were analyzed using R-T qPCR. In addition the amount of glutathione, flavonoids and phenolic compounds were also analyzed. Data show that HMA1 and HMA3 expression in the leaf samples were gradually increased with increase in metal levels in plants till 50 µM to 100 µM and then expression level gradually drops in the leaves when plants were subjected to high metal comcentration (above 100 µM Cu). This indicate that metal ATPases are not the only transporters responsible in metal accumulation and tolerance but there are some other factors (possibly other metal transporters) involved in metal accumulation and tolerance. Bioinformatic analyses showed that HMA1-HMA4 play an important role in metal transport in Brassica spp. Therefore, studies showed a significant interaction between several metal ATPases and other metal transporters and thus the amount of glutathione were analyzed in these plant species grown at different Cu levels. The glutathion accumulation pattern resembled to the expression pattern of metal ATPases. Especially in B. juncea L. The accumulation pattern of other flavonoids and phenolic compoundsvaries in the plants subjected to different Cu levels. The results of this thesis will provide an important information in understanding the the accumulation and detoxification mechanisim of Cu in Brassica spp.