Induction of Systemic Acquired Resistance in Pea against Rust (Uromyces pisi) by Exogenous Application of Biotic and Abiotic Inducers

Pea breeding for rust resistance is hampered by the little resistance available in pea. In an attempt to validate alternative control methods, we evaluated the potential of systemic acquired resistance for rust control in pea by biotic and abiotic inducers. Challenge with a virulent or with an avirulent rust isolate prior to pea rust inoculation did not induce resistance either locally or systemically. Exogenous application of salicylic acid in the range 5-10 mm prior to rust inoculation did not protect against rust locally, but reduced rust infection systemically in first upper leaf node although not in the upper ones. Some phytotoxicity was observed at 10 mm. Exogenous application of benzothiadiazole in the range 1-10 mm provided locally a 30-40% reduction in infection frequency. At least 5 mm was needed to reduce rust infection systemically in first upper leaf, and 10 mm in upper ones. Exogenous application of dl-3-amino-n-butyric acid (BABA) provided locally a 45-58% reduction in infection frequency, while systemically a 33-58 and 49-58% reduction of rust symptoms was achieved on leaves at second and third nodes respectively. BABA application was not associated with symptoms of phytotoxicity.