Efficacy of arbuscular mycorrhizal fungi and endophytic strain Epicoccum nigrum ASU11 as biocontrol agents against blackleg disease of potato caused by bacterial strain Pectobacterium carotovora subsp. atrosepticum PHY7

This work was aimed to evaluate the efficacy of arbuscular mycorrhizal fungi (AMF) and the endophytic fungal strain Epicoccum nigrum ASU11 (Epi) to control potato blackleg caused by bacterial stain Pectobacterium carotovora subsp. atrosepticum PHY7 (Pca). E. nigrum showed unique colonization frequency properties of potato plants (73.3% colonization frequency). Furthermore, the endophytic fungus exhibited antagonistic capability against pathogenic bacteria with inhibition zone 18 ± 0.5 mm. The AMF and Epi individually or in combination reduced Pca population in vivo experiment. The highest level of reduction was recorded in combination of AMF+ Epi. Also, infected potato plants treated with the two bioagents showed the highest weight of potato tubers in comparison to infected control. The enhancement of potato plants growth and the elevation of blackleg disease symptoms by bioagents (Epi + AMF) could be attributed to promoting the systemic plant resistance through the decrease of reactive oxygen species (ROS), malondialdehyde content (MDA), glutathione-s-transferase (GST), soluble peroxidase (SPO), ionic peroxidase (IPO), polyphenol oxidase (PPO), phenyl alanine ammonialyase (PAL) and lignin content. Moreover, they enhance the content of potato phenolics, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX) content. These results detected the potentiality of AMF and E. nigrum to promote potato growth and decrease the disease severity of blackleg disease. These biocontrol agents may have promising prospective strategies in potato crop protection and increase the feasibility of agriculture crop protection. The results reported herein are expected to provide competitive economic outcomes for sustainable cropping protection systems.