Induction of systemic resistance to Orobanche crenata in lentil by exogenous application of salicylic acid and indole acetic acid

Abstract

Orobanche crenata parasitism on lentil (Lens culinaris Medik) is one of the most destructive factors for this crop in Morocco. Field and pot assays were performed to study the mitigation of O. crenata stress on two lentil genotypes, Bakria (partially resistant to O. crenata) and Zaaria (susceptible), using salicylic acid (SA) and indole acetic acid (IAA). These two hormones were applied separately at concentrations of 1 mM and 0.09 mM, respectively, using seed pre-treatment and/or foliar spray methods. SA and IAA seed pre-treatment for the susceptible genotype Zaaria and foliar spray for the resistant genotype Bakria gave the best control of O. crenata under field and controlled conditions. This control reached ~91% in Zaaria and 83% in Bakria and was sometimes accompanied by an increase in plant growth and seed yield compared to the untreated plants. Biochemical assays showed that SA and IAA reduced O. crenata infestation in lentil through induction of systemic acquired resistance characterized by increasing activities of phenol metabolizing enzymes (phenylalanine ammonia-lyase, peroxidase, and polyphenol oxidase) implicated in natural defense systems of plants. Treatment of plants with SA or IAA could be an alternative strategy of crop protection with more satisfactory preservation of the environment.