BIOCHEMICAL AND PHYSIOLOGICAL-RESPONSES OF RESISTANT AND SUSCEPTIBLE WHEAT TO RUSSIAN WHEAT APHID INFESTATION

The effect of Russian wheat aphid (RWA), Diuraphis noxia infestation on protein, free amino acid, free proline, chlorophyll and phenolic contents as well as respiration rate was studied in resistant (cv Tugela-DN) and susceptible (cv Tugela) wheat under greenhouse conditions. The results confirm that RWA infestation poses a stress condition for both resistant and susceptible wheat. Responses of resistant plants to stress induced by RWA infestation in many respects resemble known resistance responses to other biotic as well as abiotic stresses. Results indicate that metabolically, resistant plants have a better ability to survive the stress condition imposed by sustained infestation. Infestation induced changes in proline content are evidently contributing to resistance. The increased phenolic content in resistant wheat after infestation may have a deterrent effect as well.