Mycorrhizal autochthonous consortium induced defense-related mechanisms of olive trees against Verticillium dahliae

Abstract

The present work aimed to investigate the effect of an autochthonous mycorrhizal consortium in enhancing olive tree tolerance against Verticillium dahliae. The bio-protective effect of this consortium “Rhizolive” on olive “Picholine Marocaine cultivar” infected with V. dahliae was assessed through monitoring disease symptoms development and through measuring the activities of enzymes involved in basal defense and secondary metabolism. The results revealed that “Rhizolive consortium” significantly (p < 0.05) reduced disease severity and incidence by 31% and 29%, respectively. The defoliation rate was also reduced by 35% in mycorrhizal-infected olive plants. “Rhizolive consortium” increased the lignin deposition and stimulated the phenylpropanoid pathway by increasing the phenylalanine ammonia-lyase (PAL) activity and accumulation of phenolic compounds in both roots and stems of plants infected with V. dahliae. The reduction in disease severity was accompanied by increased levels of lignin concentration, PAL activity and polyphenol content, particularly in the stems of olive plants. Our results clearly show that “Rhizolive consortium” inoculum protects olive tree from V. dahliae attacks and could thus constitute a biological approach contributing to the suppression of this telluric vascular pathogen.