Micronutrient deficiency influences plant growth and activities of superoxide dismutases in narrow-leafed lupins

The effect of copper (Cu), zinc (Zn) or manganese (Mn) deficiency on the gr owth and activity of superoxide dismutase (SOD) forms was investigated in s eedlings of narrow-leafed lupins (Lupinus angustifolius L.). Plants grown w ithout Zn developed Zn deficiency symptoms 24 d after sowing (DAS), and tho se grown without Mn showed Mn deficiency symptoms 31 DAS. However, plants g rown without Cu did not show visible leaf symptoms. Shoot dry weight was de creased by Zn and Mn deficiency 24 DAS, and by Cu deficiency 31 DAS. Solubl e protein concentration was reduced considerably by Zn deficiency 24 DAS, b ut was not affected by Cu deficiency until 31 DAS. In contrast, soluble pro tein concentration in Mn-deficient plants was higher than in control plants 31 DAS. Shoot concentration of micronutrients which were not supplied to p lants decreased significantly, with a simultaneous increase in concentratio n of one or more of the other nutrients analysed. The activities of total S OD, MnSOD and Cu/ZnSOD on a fresh weight basis declined drastically in -Cu and -Zn plants 24 DAS. On the contrary, the activities of total SOD and Cu/ ZnSOD on either a fresh weight or soluble protein basis increased markedly in -Mn plants 24 DAS, and MnSOD activity increased significantly in these p lants 31 DAS. It was concluded that micronutrient deficiency (Cu, Zn or Mn) altered the activities of SOD forms depending on the kind and severity of the deficiency stress. Manipulation of the capacity of plants to tolerate o xidative stress may influence their capacity to tolerate micronutrient defi ciency. (C) 1999 Annals of Botany Company.