Poster: Biology & Disease Mgmt: Genetics of Resistance
Induction of resistance in cultivated peanut against peanut early leaf spot by salicylic acid
K. BOWEN (1), L. Gong (2) (1) Auburn University, U.S.A.; (2) Auburn University, U.S.A.
Cultivated peanut (Arachis hypogaea L.) is an economically important crop for the United States and throughout the world. Cercospora arachidicola (Ca), the causal agent of early leaf spot (ELS) on cultivated peanut, can cause yield losses of up to 50%. Since earlier work reported inconsistent results with salicylic acid (SA) relative to peanut pathogens, we sought to examine the ability of SA to induce resistance against ELS on a high-oleic cultivar. We evaluated the effect of spraying three rates of SA (100, 200, and 300 µM) at 3, 5, and 7 days before inoculation (DBI) with ELS in whole peanut plants (cultivar GA-09B) in a growth chamber. Each treatment was replicated three times. At 15 days after inoculation (DAI), all SA treatments had significantly fewer lesions (3.1, 2.8, and 2.5 lesions with increasing SA rates; and 1.9, 3.0, and 3.6 lesions with increasing DBI), compared with the control (12.7). At 42 DAI, all sporulating lesions from SA treated plants tended to produce fewer spores compared with the control (170.0); for example, 27.2 with 300 µM SA, 54.5 with 3 DBI, and 31.0 with 7 DBI. Although there were fewer lesions on SA treated plants, these lesions were larger than those on the control. Results of this study suggest that SA plays at least a transient role in ELS resistance in peanut cultivar GA-09B.