Role of Salicylic Acid in Tomato Defense against Cotton Bollworm, Helicoverpa armigera Hubner

Abstract

We investigated the role of the salicylic acid (SA) signaling pathway in defense responses of tomato plants to the herbivore, cotton bollworm. After exposure to the cotton bollworm, tomato leaves rapidly accumulated a high level of SA. The transcription of PR1 and BGL2 genes, the marker genes of SA pathway, was up-regulated. An enhanced endogenous SA level was accompanied by an increase in the endogenous H2O2 level as compared with controls. Spraying tomato plants with a solution containing either SA or methyl salicylic acid (Me-SA), the H2O2 level dramatically increased. These data proved that the SA pathway was involved in the tomato plant defense responses to the herbivore.

Mechanisms of plant defense against insect herbivores

“…Production of ROS by SA pathway has been proposed to induce resistance in plants against insect pests, e.g., in tomato plants against H. armigera. 135 H 2 O 2 induced by SA in plants defends them against various insect pests since H 2 O 2 actively damages the digestive system of insects leading to reduced growth and development. 35,135 Furthermore, SA signals the release of plant volatiles that attract the natural enemies of insect pests, e.g., Lima bean and tomato plants infested by spider mite attract the natural enemies of spider mite.…”

“…135 H 2 O 2 induced by SA in plants defends them against various insect pests since H 2 O 2 actively damages the digestive system of insects leading to reduced growth and development. 35,135 Furthermore, SA signals the release of plant volatiles that attract the natural enemies of insect pests, e.g., Lima bean and tomato plants infested by spider mite attract the natural enemies of spider mite. 97 However, it has been reported that SA and JA act antagonistically, where SA inhibits the activity of JA and vice versa.…”

Role of salicylic acid in induction of plant defense system in chickpea (Cicer arietinumL.)

“…2,3,19 Elicitors such as jasmonic acid, SA and ethylene have been found to induce such enzymes in plants. [2][3][4][5][6][7][8][9][10][11] Induction of these enzymes by exogenous application of SA and their role in plant defense against various stresses including salinity, 10 drought, 21 pathogens, 4,22 and insects, 8,20,23 has been studied in many plants.…”

Comparisons of LIPOXYGENASE3- and JASMONATE-RESISTANT4/6-Silenced Plants Reveal That Jasmonic Acid and Jasmonic Acid-Amino Acid Conjugates Play Different Roles in Herbivore Resistance of Nicotiana attenuata

“…Interestingly, many induced defenses are found not only in damaged local leaves but also in undamaged systemic tissues located distal to the attack sites (van Dam et al, 2001;Schilmiller and Howe, 2005;Wasternack et al, 2006), thus allowing the plant also to cope with highly mobile herbivores. Many plant hormones are involved in these responses, including jasmonates, salicylates, and ethylene (Kahl et al, 2000;Ziegler et al, 2001;Peng et al, 2004;Halitschke and Baldwin, 2005;von Dahl et al, 2007). Among these, the jasmonate-signaling pathway plays a central role.…”