Potential of ethyl acetate fractions of Stryphnodendron adstringens shells and fruit extracts of Caesalpinia ferrea to control bacterial leaf speck and on the potentiation of defense enzymes in tomato

Abstract

Considering the importance of bacterial leaf speck (Pseudomonas syringae pv. tomato) in reducing tomato yield and difficulties in disease control, this study investigated the effects of fractions of shells extract of Stryphnodendron adstringens (Sa) and fruit extract of Caesalpinia ferrea (Cf) compared to Acibenzolar-S-Methyl (ASM) on reducing bacterial leaf speck symptoms and on the potentiation of the activities of defense enzymes. The number of lesions per plant (NLP) was significantly lower in plants treated with the ethyl acetate fraction (EAF) of S. adstringens (Sa) and ASM compared to other treatments (EAF of Cf, n-butanol fractions of Sa and Cf, aqueous fractions of Sa and Cf and sterile distilled water). The bacteria were inhibited by the EAF of Sa and EAF of Cf and n-butanol fractions of Sa and Cf according to the bioautography assay. Saponins and tannins were the two major compounds found in these fractions based on the phytochemical analysis. Peroxidase (POX), polyphenoloxidase (PPO), β-1,3-glucanase (GLU) and phenylalanine ammonia-lyase (PAL) activities were determined on the leaves of plants treated with EAF Sa, ASM and sterile distilled water. Both POX and PAL activities were higher at 3 and 6 days after inoculation (dai), while the PPO and GLU activities were higher from 9 to 12 dai. It is suggested that saponins increased tomato resistance to P. s. pv. tomato because no antimicrobial activity against the bacteria was observed. In conclusion, the EAF Sa was very efficient in reducing bacterial leaf speck symptoms in conditions where the POX, PPO, PAL and GLU activities played a pivotal role in increasing tomato resistance to the disease.

Biochemical insights into basal and induced resistance in cabbage to black rot

“…The ASM‐sprayed‐inoculated plants displayed higher PPO activity than non‐sprayed plants, which is consistent with results obtained in tomato plants that were sprayed with ASM and inoculated with Pst (Cavalcante et al, ) or X. gardneri (Luiz, Felipini, Costa, & Piero, ). The ability of ASM in increasing PPO activity and decreasing disease severity was also recorded in snap bean infected with Xap (Vigo et al, ).…”

“…Consistent with our findings, GLU was identified as an important defence component in turnip plants against Xcc infection (Conrads‐Strauch et al, ). Increases in GLU activity and reduction in bacterial leaf speck intensity owing to ASM spray in tomato plants were also recorded (Cavalcante et al, ). The PR ‐2 (β‐1,3‐glucanase gene) expression was found to be increased by ASM in orange plants inoculated with Xac (Francis et al, ).…”

“…Oxidation of phenolics by PPO triggers the production of quinones, which are able to inactivate pectolytic enzymes and have antimicrobial activity (Cavalcante, Resende, Leite, Oliveira, & Rodrigues, ). PPO activity was similarly increased by the two Xcc isolates indicating that PPO played a role in cabbage defence against Xcc infection, which is consistent with observations made for snap bean and tomato plants in which PPO was demonstrated to be induced by Xanthomonas axonopodis pv.…”

“…vesicatoria infection showed that bacterial growth was restricted only in flowers tissue, which was related to the earlier induction of CHI in such organ (O'Garro & Charlemance, ). The higher activity of PPO observed for plants from cultivar LV may have contributed to its resistance to Xcc due to its role in deactivating pectolytic enzymes and antimicrobial activity by producing quinones (Cavalcante et al, ). The analysis of the reaction of 18 cultivars of potato to soft rot ( Pectobacterium atrosepticum , P. carotovorum subsp.…”

Phosphites of manganese and zinc potentiate the resistance of common bean against infection by Xanthomonas axonopodis pv. phaseoli

“…The conversion of the amino acid L ‐phenylalanine to trans‐cinnamic acid by PAL produces phenolics of antimicrobial nature and provides precursors for lignin synthesis (Campbell & Sederoff, 1996). Oxidation of phenolics by PPO triggers the production of quinones, which can inactivate pectolytic enzymes besides displaying antimicrobial activity (Cavalcante, Resende, Leite, Oliveira, & Rodrigues, 2014). The Xapf infection resulted in sharp increases in GLU, PAL and PPO activities.…”