Mechanisms underlying salicylic acid on root parameters and antioxidant enzyme activity of potato plant under Lelliottia amnigena stress

Abstract

Salicylic acid (SA) plays many roles in plant physiology. In addition to pathogenesis-related resistance, SA is involved in the response to biotic stress. There are no adequate studies on mechanism underlying SA-mitigated Lelliottia amnigena infestations in potato (Solanum tuberosum L.) plant. Therefore, this study evaluated the mechanisms of SA on antioxidant enzyme activity of potato plant roots under L. amnigena stress. The bacterial suspension (3.69 × 107 CFU mL-1) at 0.3 mL was inoculated into potato plants through stem injection. After 24 h, different SA concentrations (0.5, 1.0, 1.5 and 2.0 mM) were sprayed to the potato plants, and water as control. The results showed that L. amnigena infestation decreased fresh weight, dry weight, and relative water content of roots by 44.8%, 11.8% and 34.8%, respectively, compared to the control. The potato plant treatment with SA increased fresh weight, dry weight, and relative water content by an average of 34.88%, 10.28% and 13.50%; increased superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) by 35.95%, 32.55%, 33.74%, 33.25%, and 38.90%; decreased malondialdehyde (MDA) and hydrogen peroxide (H2O2) content in potato plant roots by 42.7% and 31.1%, respectively, under L. amnigena stress compared to control. Treatment with SA induced transcriptional levels of the SOD, POD, CAT and glutathione S-transferase (GST) gene expression across the four levels of SA by an average of 3.12-fold, 3.46-fold, 2.93-fold and 3.83-fold, respectively, compared to control. Salicylic acid increased antioxidant enzymes activity in roots of potato plant under L. amnigena stress.