NICKEL AFFECTS PROLINE ACCUMULATION, PROTEIN CONTENT AND GENE EXPRESSION OF ANTIOXIDANT ENZYMES OF MAIZE (ZEA MAYS L.) GENOTYPES

Abstract

This study was conducted to investigate the effects of nickel concentrations on gene expression and certain physiological parameters of maize (Zea mays L.) genotypes. Three Iraqi varieties (5018, Baghdad-3 and Fajr-1) were exposed to four concentrations of nickel (0, 200, 300 and 400 ppm). The results showed high proline and protein contents of Fajr-1 variety, which recorded the values of 3.58 μmole/g and 8.699%, respectively. There was a gradual increase in proline content under the influence of the elevated concentrations of nickel (18.75%, 25.83% and 49.16%). In addition to significant increase in the total protein content in response to nickel concentrations as 31.78%, 54.05% and 59.61%. These findings were consistent with gene expression results, which revealed that nickel affected the gene expression levels of three major antioxidant enzymes (SOD, GPX and MDAR). In general, nickel concentrations of 300 and 400ppm increased gene expression, where Fajr- 1 variety recorded the highest level of SOD gene (5.314) and MDAR gene (354.588), when exposed to 300 ppm of nickel; while Baghdad-3 variety with 400 ppm scored the highest expression level for GPX gene (16.679).