jasmonic Acid-Mediated-Induced Resistance in Groundnut.pdf

Jasmonic Acid-Mediated-Induced Resistance in Groundnut (Arachis hypogaea L.) Against Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) Abdul Rashid War ? Michael Gabriel Paulraj ? Mohd Yousf War ? Savarimuthu Ignacimuthu Received: 31 January 2011 / Accepted: 26 April 2011 / Published online: 19 May 2011  Springer Science+Business Media, LLC 2011 Abstract Jasmonic acid (JA) acts as a signal molecule to induce resistance in plants against herbivores and its levels are elevated in plants after wounding or insect damage. Groundnut is an important crop in many tropical and subtropical regions worldwide, but there is surprisingly little knowledge on its induced defenses against herbivores. The effect of JA as a spray on induced resistance in three groundnut genotypes, namely, ICGV 86699 (resistant), NCAc 343 (resistant), and TMV 2 (susceptible), against Helicoverpa armigera was studied. The activity of oxida- tive enzymes [peroxidase (POD) and polyphenol oxidase (PPO)] and the amounts of other host plant defense com- ponents [total phenols, hydrogen peroxide (H2O2), mal- ondialdehyde (MDA), and protein content] were recorded at 24, 48, 72, and 96 h after pretreatment (1 day) with JA followed by infestation with H. armigera (PJA ? HIN) and H. armigera infestation with simultaneous JA appli- cation (HIN ? JA) to understand the consequences of induced resistance in groundnut. The plant damage, larval survival, and larval weights were also recorded. There was a significant increase in POD and PPO activities and in the amounts of total phenols, H2O2, MDA, and proteins in PJA ? HIN- and JA ? HIN-treated plants as compared to the plants treated with JA and infested with H. armigera individually and to untreated control plants. Among all the genotypes, the strongest induction of defense was observed in the ICGV 86699 genotype. It is concluded that pretreatment with JA and its application during low levels of insect infestation can increase the levels of host plant resistanc