Enhanced systemic resistance to bacterial speck disease caused by Pseudomonas syringae pv. tomato by dl‐β‐aminobutyric acid under salt stress

Abstract

Plants have evolved different but interconnected strategies to defend themselves against microbial pathogens and stress conditions. The defense responses of tomato (Lycopersicon esculentum Mill) seedlings treated with DL-b-aminobutyric acid (BABA) were investigated with and without abiotic stress (100 mM NaCl) against bacterial speck disease caused by Pseudomonas syringae pv. tomato. The plants were sprayed with 50, 125, 250 or 500 mg ml 21 BABA and were inoculated with 10 8 colony-forming units ml 21 bacterial suspension 1 day after treatment. Abiotic stress led to an increase in plant resistance. When BABA was additionally applied as a foliar spray at 125 mg ml 21 , the effect on plants was almost identical to that on plants that were sprayed with BABA at 500 mg ml 21 alone. The bacterial multiplication in the plants was 250-fold lower than in the water-treated (control) plants and in plants that were sprayed with 500 mg ml 21 BABA alone within 48 h postinoculation (hpi). Physiological studies were carried out in the plants treated with BABA in order to investigate the reason for this synergistic effect. Abiotic stress with BABA spray resulted in high H 2 O 2 generation and guaiacol peroxidase activity in the plants. The activity of the enzymatic antioxidative protective system of the plants, superoxide dismutase, ascorbate peroxidase and catalase (CAT), also showed a significant delayed increase in BABA-treated plants under abiotic stress conditions. These increases in enzyme activity coincided with the initiation of the most suppressive effect of BABA on bacterial growth by 24 hpi, which were significantly higher than the control. Salt stress alone did not lead to any significant increase in CAT activity, but salt stress with BABA did. These findings indicate a synergistic effect between salt stress and BABA at low concentrations, resulting in induced plant resistance. Furthermore, a stress regulation effect of BABA under abiotic stress can be associated with plant resistance.

Induction of resistance in pepper against Xanthomonas euvesicatoria by β-aminobutyric acid

“…CAT activity was increased in tomato by BABA following Pseudomonas syringae pv. tomato invasion (Baysal et al 2007). In summary, the role of BABA for enhancing resistance of pepper against X. euvesicatoria was confirmed in this study.…”

Post infection application of DL-3-amino-butyric acid (BABA) induces multiple forms of resistance against Bremia lactucae in lettuce

“…downy mildew in grapevines (Reuveni et al 2001), downy mildew in lettuce , moldy core in apple fruits (Reuveni et al 2003), late blight in potato and tomato, and sudden wilt in melon (Cohen 2002). BABA acts synergistically with Bion® or with metalaxyl to protect tobacco against downy mildew (Cohen 2002), with mancozeb to control downy mildew in cucumbers (Baider and Cohen 2003) and with NaCl to control bacterial speck in tomato (Baysal et al 2007). …”

Induction of resistance to Meloidogyne incognita by DL-Beta amino butyric acid under salt stress condition

“…Previous studies have reported a novel alternative that simultaneously uses BABA and low, tolerable levels of salt stress to control bacterial spot disease caused by Pseudomonas syringae pv. tomato (Baysal et al 2007).…”