Control of Aspergillus niger infection in varieties of Arachis hypogeae L. by supplementation of zinc ions during seed germination

Three varieties of Arachis hypogeae, GG 11, GG 20 and GG 24, were compared for resistance against A. niger. GG 20 showed the least disease severity. Infection with A. niger resulted in a rapid increase in NADPH oxidase, Glutathione reductase (GR) and salicylic acid in all the three varieties, indicating hyper increase of reactive oxygen species (ROS) and activation of phenyl propanoid pathway. Ferric reducing antioxidant power value was found to be decreasing due to infection in all the three varieties, confirming the role of ROS in pathogenesis. Since A. niger was found to cause pathogenesis by oxidative stress, the treatment of zinc was given as an antioxidant and its effect was studied. The application of zinc inhibited NADPH oxidase and GR activity in the control as well as in the infected GG 11 and GG 24 varieties but induced in the tolerant variety GG 20. Because zinc treatment could control the ROS in GG 11 and GG 24 varieties, disease severity was reduced but in GG 20 variety, zinc treatment aggravated ROS levels and also the disease severity. The protein profile of GG 20 in comparison to GG 11 and GG 24 varieties revealed one oligomeric protein of 110 kD as one of the responsible factors for its resistance. Total oil and its iodine value were found little higher in GG 20 variety than in other two varieties. It was found that the control of ROS could control the A. niger infection in Arachis hypogeae.