Priming of camalexin accumulation in induced systemic resistance by beneficial bacteria against Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000

Abstract

Plants harbor various beneficial microbes that modulate their innate immunity, resulting in an induced systemic resistance (ISR) against a broad range of pathogens. Camalexin is an integral part of Arabidopsis innate immunity, but the contribution of camalexin biosynthesis in ISR is poorly investigated. In this study, we focused on the primed camalexin accumulation by two beneficial bacteria, Pseudomonas fluorescens and Bacillus subtilis and its role in the ISR against Botrytis cinerea and Pseudomonas syringae Pst DC3000. Our data provide evidence that colonization of A. thaliana roots by beneficial bacteria triggers ISR against both pathogens and primes plants for enhanced accumulation of camalexin and CYP71A12 transcript in leaf tissues. The highest responses were observed in P. fluorescens-ISR against B. cinerea, while B. subtilis was more efficient against Pst DC3000. Analysis of cyp71a12 and pad3 mutants revealed that the loss of camalexin synthesis affected ISR mediated by both bacteria against B. cinerea. Data revealed a significant contribution of CYP71A12 and PAD3 to the pathogen-triggered accumulation of camalexin, while PAD3 does not seem to contribute to ISR against Pst DC3000. This pointed out a significant contribution of camalexin in ISR against B. cinerea, but not always against the Pst DC3000. Experiments with Arabidopsis mutants compromised in different hormonal signaling pathways highlighted that B. subtilis stimulates similar signaling pathways upon infection with both pathogens, since SA but no JA and ET are required for ISR-camalexin accumulation. However, P. fluorescens-induced ISR differs depending on the pathogen. In this case, both SA and JA are required for camalexin accumulation upon B. cinerea infection, while camalexin is not necessary for priming against Pst DC3000.

If All Else Fails: Impact of Silicon Accumulation in Maize Leaves on Volatile Emissions and Oviposition Site Selection of Spodoptera exigua Hübner

“…Jasmonic Acid Quanti cation. Jasmonic acid was extracted following the procedure described in Nguyen et al (2019). JA was extracted from plants subjected to similar treatments as those used for VOC analyses.…”

The Bacterial Volatile Organic Compound N,N-Dimethylhexadecylamine Induces Long-Lasting Developmental and Immune Responses throughout The Life Cycle of Arabidopsis thaliana

“…Plant defense responses are determined mainly by the pathogen attack strategies; as such, necrotrophic pathogens that usually damage the host tissues activate the JA/ET pathway, which in turn leads to the production of defensins [ 11 , 12 ]. Species of beneficial bacteria as part of a healthy microbiome also induce the JA/ET pathway; these bacteria do not really attack their host but produce a diversity of compounds that elicit the plant defense responses [ 13 , 14 ]. Boosting immunity is costly, as it consumes energy in detriment for plant growth [ 15 ].…”

“…Application of some metabolites such as β and γ-aminobutyric acids, BABA and GABA, respectively, or the tricarboxylates citrate and fumarate, induces a priming state that strengthens the plant immune system, that is, induces priming at a low energetic cost and considerably reduce damage upon pathogen challenge [ 16 , 17 , 18 ]. Beneficial bacteria, as well as their compounds, also prime the plant immune system [ 14 , 19 ]. Among the bacterial compounds, N -acyl- L -homoserine lactones (AHLs) are particularly interesting, acting as highly specific communication systems among bacterial species, also termed quorum-sensing systems.…”

The IRE1-bZIP60 branch of Unfolded Protein Response is required forArabidopsisimmune response toBotrytis cinerea

“…Cellular mechanisms regulating the induction of JA-dependent genes are frequently investigated through the measurement of the induction of genes such as PDF1.2 or ORA59, while PATHOGENESIS-RELATED-1 (PR1) serves as a marker gene for SA (Zander et al ., 2010). A typical response of plants facing necrotrophic pathogens is the production in Arabidopsis of the phytoalexin camalexin through SA or JA signalling pathways, depending on the invading pathogen (Nguyen et al ., 2022). The last step of camalexin synthesis is catalysed by the cytochrome P450 CYP71B15 (PAD3) which mRNA accumulation correlates with camalexin production (Glawischnig, 2007).…”