Tomato Bio-Protection Induced by Pseudomonas fluorescens N21.4 Involves ROS Scavenging Enzymes and PRs, without Compromising Plant Growth

Abstract

Aims: to discover the interrelationship between growth, protection and photosynthesis induced by Pseudomonas fluorescens N21.4 in tomato (Lycopersicum sculentum) challenged with the leaf pathogen Xanthomonas campestris, and to define its priming fingerprint. Methods: Photosynthesis was determined by fluorescence; plant protection was evaluated by relative disease incidence, enzyme activities by specific colorimetric assays and gene expression by qPCR. Changes in Reactive Oxygen Species (ROS) scavenging cycle enzymes and pathogenesis related protein activity and expression were determined as metabolic and genetic markers of induction of systemic resistance. Results: N21.4 significantly protected plants and increased dry weight. Growth increase is supported by significant increases in photochemical quenching together with significant decreases in energy dissipation (Non-Photochemical Quenching, NPQ). Protection was associated with changes in ROS scavenging cycle enzymes, which were significantly increased on N21.4 + pathogen challenged plants, supporting the priming effect. Superoxide Dismutase (SOD) was a good indicator of biotic stress, showing similar levels in pathogen- and N21.4-treated plants. Similarly, the activity of defense-related enzymes, ß-1,3-glucanase and chitinase significantly increased in post-pathogen challenge state; changes in gene expression were not coupled to activity. Conclusions: protection does not compromise plant growth; N21.4 priming fingerprint is defined by enhanced photochemical quenching and decreased energy dissipation, enhanced chlorophylls, primed ROS scavenging cycle enzyme activity, and glucanase and chitinase activity.

Application of 6-Pentyl-α-Pyrone in the Nutrient Solution Used in Tomato Soilless Cultivation to Inhibit Fusarium oxysporum HF-26 Growth and Development

“…Furthermore, the antifungal-nutrient solution containing 6-PP used in the present study had 70.71% efficacy, consistent with that reported for antifungal-nutrient solutions containing prochloraz and carbendazim (Figure 4, Table 2). When plants are attacked by pests, fungi, and other adverse conditions ROS and defence-related enzymes are activated and plant proline-rich proteins are produced and accumulate in plant tissues improving plant resistance to pathogen infection and adapting to adverse conditions [47]. In the present study, treatment with an antifungal-nutrient solution containing 6-PP markedly increased the content of defence-related enzymes at 24 hpi compared with that at other time points.…”

Ultralong‐lasting plasma‐activated water inhibits pathogens and improves plant disease resistance in soft rot‐infected hydroponic lettuce

“…[45] For example, the β-1,3-glucanase could destroy the biomolecules of the cell wall thereby suppressing the survival of pathogens. [46][47][48][49] In this study, though the invasion of pathogens has enhanced the β-1,3-glucanase activity, its activity in the ULPAW-treated inoculated lettuce roots was higher compared with non-ULPAW treated inoculated plants (Figure 7a). These results indicate that ULPAW treatment was more effective for enhancing disease resistance-related enzyme activity to tackle pathogen invasion.…”