Differential responses of Oryza sativa secondary metabolism to biotic interactions with cooperative, commensal and phytopathogenic bacteria

Abstract

Profiling of plant secondary metabolite allows to differentiate the different types of ecological interactions established between rice and bacteria. Rice responds to ecologically distinct bacteria by altering its content of flavonoids and hydroxycinnamic acid derivatives. Plants' growth and physiology are strongly influenced by the biotic interactions that plants establish with soil bacterial populations. Plants are able to sense and to respond accordingly to ecologically distinct bacteria, by inducing defense pathways against pathogens to prevent parasitic interactions, and by stimulating the growth of root-associated beneficial or commensal bacteria through root exudation. Plant secondary metabolism is expected to play a major role in this control. However, secondary metabolite responses of a same plant to cooperative, commensal and deleterious bacteria have so far never been compared. The impact of the plant growth-promoting rhizobacteria (PGPR) Azospirillum lipoferum 4B on the secondary metabolite profiles of two Oryza sativa L. cultivars (Cigalon and Nipponbare) was compared to that of a rice pathogen Burkholderia glumae AU6208, the causing agent of bacterial panicle blight and of a commensal environmental bacteria Escherichia coli B6. Root and shoot rice extracts were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC). Principal component analyses (PCAs) pinpointed discriminant secondary metabolites, which were characterized by mass spectrometry. Direct comparison of metabolic profiles evidenced that each bacterial ecological interaction induced distinct qualitative and quantitative modifications of rice secondary metabolism, by altering the content of numerous flavonoid compounds and hydroxycinnamic acid (HCA) derivatives. Secondary metabolism varied according to the cultivars and the interaction types, demonstrating the relevance of secondary metabolic profiling for studying plant-bacteria biotic interactions.

Metabolic Profiling of PGPR-Treated Tomato Plants Reveal Priming-Related Adaptations of Secondary Metabolites and Aromatic Amino Acids

“…In addition, this metabolic reprogramming was characterized by amino acids, organic acids, HCA derivatives, hydroxybenzoic acids, fatty acids, and glycoalkaloids (Table 1). In previous studies, inoculation of rice and maize with Azospirillum species was reported to affect HCAs and benzoxazines, respectively, and strain-specific metabolic changes were observed [48,49]. Also, using different microbial-derived priming agents, [37] showed that lipopolysaccharides, chitosan, and flagellin petide (flg22) triggered the biosynthesis of HCAs, and these were specific to each priming agent.…”

Reactive oxygen species and hormone signaling cascades in endophytic bacterium induced essential oil accumulation in Atractylodes lancea

“…Secondary metabolite synthesis is a strategy used by plants to adapt to different environments and cope with stresses (Chamam et al 2015). Many plant secondary metabolites, such as terpenoids, phenols, and alkaloids, also have value as medicines, spices, pesticides, and additives (Murthy et al 2014).…”

A common metabolomic signature is observed upon inoculation of rice roots with various rhizobacteria

“…Interestingly, the four HCAA, N ‐ p ‐coumaroylputrescine (C29), N ‐feruloylputrescine (C37), N ‐feruloylcadaverine (C43), N ‐feruloylglycine (C48), as well as several HCA‐hexosides appeared to be strongly down‐accumulated in response to the bacterial pathogen B. glumae . A contrasted accumulation of phenolic acids has previously been reported in inoculated rice, indicating that plant use common metabolites to interact with microorganisms but in different ways (Chamam et al ). The contrasted detection of HCA derivatives between the PGPR versus the pathogen treatment could be due to a differential availability and hence efficiency of metabolites extraction caused by modifications of plant cell wall.…”

“…The contrasted accumulation of secondary metabolites, already reported in rice but without identification of the specific compounds (Chamam et al ), indicates that plant use common metabolites to interact with microorganisms but in different ways. Plants perceived surrounding microorganisms, either beneficial or pathogenic, via structural and conserved elements composing the microbe, named MAMPs (Microbe‐Associated Molecular Patterns).…”