Metabolite profiling reveals a role for intercellular dihydrocamalexic acid in the response of mature Arabidopsis thaliana to Pseudomonas syringae

Novel Time-dependent Multi-omics Integration in Sepsis-associated Liver Dysfunction

The recently developed technologies that allow the analysis of each single omics have provided an unbiased insight into ongoing disease processes. However, it remains challenging to specify the study design for the subsequent integration strategies that can associate sepsis pathophysiology and clinical outcomes. Here, we conducted a time-dependent multi-omics integration (TDMI) in a sepsis-associated liver dysfunction (SALD) model. We successfully deduced the relation of the Toll-like receptor 4 (TLR4) pathway with SALD. Although TLR4 is a critical factor in sepsis progression, it is not specified in single-omics analyses but only in the TDMI analysis. This finding indicates that the TDMI-based approach is more advantageous than single-omics analyses in terms of exploring the underlying pathophysiological mechanism of SALD. Furthermore, TDMI-based approach can be an ideal paradigm for insightful biological interpretations of multi-omics datasets that will potentially reveal novel insights into basic biology, health, and diseases, thus allowing the identification of promising candidates for therapeutic strategies.

Specialized metabolites as versatile tools in shaping plant-microbe associations

Plants are rich repository of a large number of chemical compounds collectively referred to as specialized metabolites. These compounds are of importance for adaptive processes including responses against changing abiotic conditions and interactions with various co-existing organisms. One of the strikingly affirmed functions of these specialized metabolites is their involvement in plants' life-long interactions with complex multi-kingdom microbiomes including both beneficial and harmful microorganisms. Recent developments in genomic and molecular biology tools not only help to generate well-curated information about regulatory and structural components of biosynthetic pathways of plant specialized metabolites but also to create and screen mutant lines defective in their synthesis. In this review, we have comprehensively surveyed the function of these specialized metabolites and discussed recent research findings demonstrating the responses of various microbes on tested mutant lines having defective biosynthesis of particular metabolites. In addition, we attempt to provide key clues about the impact of these metabolites on the assembly of the plant microbiome by summarizing the major findings of recent comparative metagenomic analyses of available mutant lines under customized and natural microbial niches. Subsequently, we delineate benchmark initiatives that aim to engineer or manipulate the biosynthetic pathways to produce specialized metabolites in heterologous systems but also to diversify their immune function. While denoting the function of these metabolites, we also discuss the critical bottlenecks associated with understanding and exploiting their function in improving plant adaptation to the environment.

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

Plants harbor various beneficial microbes that modulate their innate immunity, resulting in induced systemic resistance (ISR) against a broad range of pathogens. Camalexin is an integral part of Arabidopsis innate immunity, but the contribution of its biosynthesis in ISR is poorly investigated. We focused on camalexin accumulation primed by two beneficial bacteria, Pseudomonas fluorescens and Bacillus subtilis, and its role in ISR against Botrytis cinerea and Pseudomonas syringae Pst DC3000. Our data show that colonization of Arabidopsis thaliana roots by beneficial bacteria triggers ISR against both pathogens and primes plants for enhanced accumulation of camalexin and CYP71A12 transcript in leaf tissues. Pseudomonas fluorescens induced the most efficient ISR response against B. cinerea, while B. subtilis was more efficient against Pst DC3000. Analysis of cyp71a12 and pad3 mutants revealed that loss of camalexin synthesis affected ISR mediated by both bacteria against B. cinerea. CYP71A12 and PAD3 contributed significantly to the pathogen-triggered accumulation of camalexin, but PAD3 does not seem to contribute to ISR against Pst DC3000. This indicated a significant contribution of camalexin in ISR against B. cinerea, but not always against 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 salicylic acid (SA), but not jasmonic acid (JA) or ethylene, is required for ISR camalexin accumulation. However, P. fluorescens-induced ISR differs depending on the pathogen; both SA and JA are required for camalexin accumulation upon B. cinerea infection, while camalexin is not necessary for priming against Pst DC3000.

Molecular characterization of three CYP450 genes reveals their role in withanolides formation and defense in Withania somnifera, the Indian Ginseng

The medicinal properties of Ashwagandha (Withania somnifera) are attributed to triterpenoid steroidal lactones, withanolides, which are proposed to be derived from phytosterol pathway, through the action of cytochrome P450 (CYP450) enzymes. Here, we report the characterization of three transcriptome-mined CYP450 genes (WsCYP749B1, WsCYP76 and WsCYP71B10), which exhibited induced expression in response to methyl jasmonate treatment indicating their role in secondary metabolism. All three WsCYP450s had the highest expression in leaf compared to other tissues. In planta characterization of WsCYP450s through virus induced gene silencing (VIGS) and transient overexpression approaches and subsequent metabolite analysis indicated differential modulation in the accumulation of certain withanolides in W. somnifera leaves. While WsCYP749B1-vigs significantly enhanced withaferin A (~ 450%) and reduced withanolide A (~ 50%), its overexpression drastically led to enhanced withanolide A (> 250%) and withanolide B (> 200%) levels and reduced 12-deoxywithastramonolide (~ 60%). Whereas WsCYP76-vigs led to reduced withanolide A (~ 60%) and its overexpression increased withanolide A (~ 150%) and reduced 12-deoxywithastramonolide (~ 60%). Silencing and overexpression of WsCYP71B10 resulted in significant reduction of withanolide B (~ 50%) and withanolide A (~ 60%), respectively. Further, while VIGS of WsCYP450s negatively affected the expression of pathogenesis-related (PR) genes and compromised tolerance to bacteria P. syringae DC3000, their overexpression in W. somnifera and transgenic tobacco led to improved tolerance to the bacteria. Overall, these results showed that the identified WsCYP450s have a role in one or several steps of withanolides biosynthetic pathway and are involved in conferring tolerance to biotic stress.

Chemical Composition, Production of Secondary Metabolites and Antioxidant Activity in Coffee Cultivars Susceptible and Partially Resistant to Bacterial Halo Blight

Coffee production is one of the main agricultural activities in Brazil, and several coffee cultivars with disease resistance have already been developed. The secondary metabolites produced by plants are closely associated with defense strategies, and the resistance of coffee cultivars to bacterial halo blight (BHB) can be related to these compounds. Therefore, this study aims to compare a partially resistant coffee cultivar (Iapar-59) and a susceptible cultivar (Mundo Novo 376/4) to BHB (Pseudomonas syringae pv. garcae) in relation to the chemical composition and antioxidant activity of the leaf extracts. In addition, this study determined the total phenolic and flavonoid contents and phenolic profiles of the Iapar-59 leaf extracts of plants inoculated with P. syringae pv. garcae. The Iapar-59 extract showed a higher content of phenolic compounds and flavonoids than the Mundo Novo 376/4 extract. Both cultivars contained gallic, chlorogenic and caffeic acids; however, the highest contents were quantified in the Iapar-59 cultivar. The leaf extracts from the Iapar-59 cultivar exhibited higher antioxidant activity. Higher concentrations of gallic, caffeic and chlorogenic acids and the presence of vanillin were detected in the extract of cultivar Iapar-59 inoculated with P. syringae pv. garcae.