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Articles by N.L. Ahmed
Total Records ( 2 ) for N.L. Ahmed
  M.A. El-Tayeb , A.E. El-Enany and N.L. Ahmed
  The effect of salicylic acid (SA: 0.5 mM) on the plant growth, copper accumulation, Cu-bound proteins and protein pattern in roots and shoots of Helianthus annuus plants under Cu stress (5 mg L–1) was studied. Cu stress reduced the fresh and dry weights of sunflower plants. Cu markedly accumulated in Cu-stressed plants. However, this accumulation of Cu was higher in roots than in shoots. Chromatography of cell free extract of Cu-binding proteins of cu-stressed plants revealed three main protein peaks in roots and four peaks in leaves. The main peak for copper is coincident with protein of molecular weight of 75 kDa and contains about 89.40 and 80.84% of the total copper in the soluble fraction in roots and leaves, respectively. Proteins pattern shows that, Cu-stress induced the synthesis of new polypeptides of 178 and 97 kDa in plant roots and 105, 81 kDa in case of plant leaves. SA increased the fresh and dry weights of Cu-stressed plants. SA lowered the Cu content both in the roots and shoots of Cu-stressed plants. This was associated an increase in the endogenous SA content in the two organs. Cu plus SA treatment revealed 4 protein peaks with molecular weights about 175, 130, 75 and 35 kDa in roots and 175, 130, 100 and 45 kDa in case of leaves. The main peak for copper is coincident with protein of molecular weight 75 kDa in roots and 100 kDa in leaves, retaining about 82.90 and 74.72% of the total copper in the soluble fraction. Under Cu stress, SA induced the synthesis of 5 new polypeptides with molecular weight ranged from 204 to 26 kDa in roots and 4 new polypeptides ranged from 189 to 6 kDa in case of leaves. The results indicate that salicylic acid can alleviate the adverse effects of copper on the growth of sunflower plants by interfering of SA in translocation of Cu and/or increasing Cu-binding proteins in sunflower.
  M.A. El-tayeb , A.E. El-Enany and N.l. Ahmed
  The ameliorative effect of salicylic acid (SA: 0.5 mM) under Cu stress (5 mg L–1) in sunflower (Helianthus annuus L.) was studied. Excess Cu reduced the fresh and dry weights of different organs (roots, stems and leaves) and photosynthetic pigments (chlorophyll a, b and carotenoids) in four-week-old plants. There was a considerable increase in Chl a/b ratio and lipid peroxidation in both the roots and leaves of plants under excess Cu. Soluble sugars and free amino acids in the roots also decreased under Cu stress. However, soluble sugars in the leaves, free amino acids in the stems and leaves and proline content in all the plant organs increased in response to Cu toxicity. Salicylic Acid (SA) significantly reduced the chlorophyll a/b ratio and the level of lipid peroxidation in Cu-stressed plants. Under excess Cu, a higher accumulation of soluble sugars, soluble proteins and free amino acids including proline occurred in plants treated with SA. Exogenous application of SA appeared to induce an adaptive response to Cu toxicity including the accumulation of organic solutes leading to protective reactions to the photosynthetic pigments and a reduction in membranes damage in sunflower.
 
 
 
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