Effect of salicylic acid on jasmonic acid-related defense response of pea seedlings to wounding

Abstract

Interactions between jasmonic acid (JA) and salicylic acid (SA) signaling pathways play important roles in the regulation and fine-tuning of induced defenses which are activated by pathogen, insect attack, or wounding. In this study, endogenous SA and JA level in pea seedlings presented opposite trends in response to wounding. Results exhibited that SA impaired the resistance to wounding of pea seedlings by means of suppressing the action of JA. Based on the fact that the wound-induced PPO activity was suppressed by SA, it could be concluded further that SA had negative effect on JA-related defense response. However, synergy between JA and SA also existed in phenolic metabolism related to PAL. Moreover, endogenous SA and salicylic acid 2- O- β- d-glucose (SAG) levels in wounded pea seedlings also appeared opposite variation tendency, and newly synthesised SAG was detected. In contrast to SA, SAG showed some synergistic action in JA-related defense response in terms of MDA, PPO activity and PAL activity, which was quite different from SA. In conclusion, these results revealed both the negative effect and some synergistic effect of SA on JA-related defense of pea in response to wounding, particularly the role of SAG.