Alteration of antioxidant gene expression in response to heavy metal stress in Trigonella foenum-graecum L.

Soil contamination with heavy metals can result in many adverse effects on the agricultural crops. In the present work, effects of different concentrations (2.5, 5, 7.5 and 10 mg L− 1) of cadmium (Cd), chromium (Cr) and lead (Pb) on the seed germination of Fenugreek plant (Trigonella foenum-graecum L.) were investigated in vitro. Reductions in the seed germination percentages and root and shoot lengths after 7 days were recorded in response to the increase in the metal concentration. Cadmium treatment showed the strongest inhibitory effect on the Fenugreek seeds regarding to the tested parameters followed by the lead treatment, while chromium exhibited the weakest. In order to detect differentially expressed genes in the Cd, Cr, or Pb treated fenugreek seedlings, their cDNAs were amplified and differentially displayed using two sets of 3-oligo(dT) arbitrary primers (RAPD-2 and RAPD-19) and one defense specific primer. The obtained differential display patterns showed some gene expression alterations in response to the heavy metal stress. In addition, gene expression analysis for the antioxidant enzymes encoding genes (CAT, POD & APX) was studied using real-time PCR technique. Varied increased expression levels of the tested genes were observed demonstrating different levels of tolerance against the three tested heavy metals.