Induction of apoplast phenolics in pepper (Capsicum annuum) leaves in response to pathogenic bacteria. (January 2020)

• Record Type: Journal Article
• Authors: Baker, C. Jacyn; Smith, Jodi M.; Yarberry, Andrea J.; Rice, Clifford
• Is Part Of: Physiological and molecular plant pathology. Volume 109(2020)
• Publication Date: 2020-01
• Subjects: AWF apoplast wash fluid -- PF Pseudomonas fluorescens -- PSS P. syringae pv. syringae -- PTAB P.s. pv. tabaci -- PTOM P.s. pv. tomato -- cfu colony forming units; Plant diseases -- Periodicals; Diseased plants -- Physiology -- Periodicals; Phytopathogenic microorganisms -- Host plants -- Periodicals; 632
• DOI: 10.1016/j.pmpp.2019.101453
• Languages: English
• ISSNs: 0885-5765

Abstract

Abstract: The objective of this study was to corroborate, in pepper, the response of tobacco to induce apoplast phenolics upon bacterial inoculation. Leaves of Bell peppers (Capsicum annuum), 6–8 weeks old, were inoculated with bacteria and analyzed for apoplast phenolics after different periods of incubation. Pseudomonas syringae pv. tabacci, 10 8 cfu ml −1, induced numerous phenolics to accumulate in the leaf apoplast after 24 h. UPLC-UV chromatograms revealed about 15 UV-peaks, some containing several components. Using this bacterial isolate, it was found that all the fully developed leaves on a single plant had a similar phenolic response based on magnitude and composition of the phenolics. Between plants, the phenolic composition was also similar, although there was more variability. The magnitude of response was proportional to the bacterial concentration between 10 5 -10 8 cfu ml −1 . Plants inoculated with water or P. fluorescens, a saprophyte, had a negligible response. When pepper plants were inoculated with different bacterial pathogens, P. s . pv. tomato and pv. syringae, there were differences in the magnitude and composition of the phenolics after 24 h. A time course showed that phenolic accumulation was underway by 7 h and appeared to peak by 24 h. The bacterial induction of apoplast phenolics in pepper, described here, corroborates the similar response previously described for tobacco. The preliminary characterization by UPLC-UV/MS suggests the apoplast phenolics found in pepper are structurally different from those in tobacco. However, the similar timing and location of the responses in both plants would suggest that their roles in the plant bacterial interaction are also similar. Further investigation of the redox and bioactivity properties of these apoplast phenolics is needed. Highlights: Second plant shown to respond to bacterial pathogens with buildup apoplast phenolics. P. fluorescens and water did not induce phenolics. P.s. tabacci induced twice the level of phenolics compared to other pathovars.