Project description:Flavonoids are stress-inducible metabolites important for plant-microbe interactions. In contrast to their well-known function in initiating rhizobia nodulation in legumes, it is unclear whether and how flavonoids may contribute to plant stress resistance through affecting non-nodulating bacteria in the root microbiome. Here we show how flavonoids preferentially attracts Aeromonadaceae in Arabidopsis thaliana root microbiome and how flavonoid-dependent recruitment of an Aeromona spp. results in enhanced plant drought resistance.
Project description:Drought is a critical issue in modern agriculture, therefore there is a need to create crops with drought resilience. The complexity of plant responses to abiotic stresses, particularly in the field of brassinosteroid (BR) signaling, has been the subject of extensive research. In this study, we unveil compelling insights indicating that the BRASSINOSTEROID INSENSITIVE 1 (BRI1) receptor in Arabidopsis and Sorghum plays a critical role as a negative regulator of drought responses. Introducing untargeted mutation in the sorghum BRI1 receptor (SbBRI1) effectively enhances the plant ability to withstand osmotic and drought stress. Through DNA Affinity Purification sequencing (DAP-Seq) we show that the sorghum BRI1-EMS-SUPPRESSOR 1 (SbBES1) transcription factor, a downstream player of the BR signaling, binds to a conserved G-box binding motif, and it is responsible for regulating BR homeostasis, as its Arabidopsis ortholog AtBES1. We further characterized the drought tolerance of sorghum bri1 mutants and decipher SbBES1-mediated regulation of phenylpropanoid pathway. Our findings suggest that SbBRI1 signaling serves as a dual purpose: under normal conditions, it regulates lignin biosynthesis by SbBES1, but during drought conditions, BES1 becomes less active, allowing the activation of the flavonoid pathway. This adaptive shift improves the photosynthetic rate and photoprotection, reinforcing crop adaptation to drought.
Project description:Flavonoids are stress-inducible metabolites important for plant-microbe interactions. In contrast to their well-known function in initiating rhizobia nodulation in legumes, it is unclear whether and how flavonoids may contribute to plant stress resistance through affecting non-nodulating bacteria in the root microbiome. Here we show how flavonoids preferentially attracts Aeromonadaceae in Arabidopsis thaliana root microbiome and how flavonoid-dependent recruitment of an Aeromona spp. results in enhanced plant Na_H1 resistance.
Project description:Drought stress is a major constraint on crop production. While Trichoderma fungi are widely recognized for enhancing plant tolerance to abiotic stresses, the fungal molecules responsible for these protective effects remain poorly defined. In this study, we investigated the role of 6-pentyl-a-pyrone (6PP), a volatile compound produced by diverse Trichoderma spp., in modulating plant responses to water deficit. Dwarf bean (Phaseolus vulgaris) seedlings grown from seeds coated with a carrier polymer delivering 6PP were significantly more tolerant to drought stress than seedlings from seeds coated with the polymer alone (control), exhibiting increased leaf area, root length, chlorophyll content, and photosynthetic rate. To elucidate the mechanisms induced by this molecule, comparative transcriptome analyses were performed in the presence and absence of 6PP under both wellwatered and drought conditions; only 49 DEGs were detected under wellwatered conditions. In contrast, 476 expressed genes were identified in drought-stressed plants grown from 6PP-coated seeds, indicating substantial transcriptional reprogramming. 6PP treatment reprogrammed stress-responsive gene networks, including pathways associated with photosynthesis, carbohydrate metabolism, phosphorylation-mediated signaling, defense responses, and oxidative stress regulation. In addition, drought-stressed plants treated with 6PP exhibited enhanced MAPK phosphorylation, providing protein-level evidence for activation of phosphorylation-mediated signaling pathways associated with stress tolerance. Functional enrichment analyses further highlight secondary metabolite pathways, including those for phenylpropanoid and flavonoid biosynthesis, suggesting enhanced production of protective compounds and maintenance of photosynthetic activity under drought stress. Several stress-related genes were modulated prior to drought exposure, indicating a possible priming effect. Collectively, our findings identify 6PP as a potential signaling molecule contributing to enhanced drought resilience and provide new insights into the molecular basis of Trichoderma-mediated stress protection.
Project description:Aims: To assess the virulence of multiple Aeromonas spp. using two models, a neonatal mouse assay and a mouse intestinal cell culture. Methods and Results: Transcriptional responses to both infection models were evaluated using microarrays. After artificial infection with a variety of Aeromonas spp., mRNA extracts from the two models were processed and hydridized to murine microarrays to determine host gene response. Definition of virulence was determined based on host mRNA production in murine neonatal intestinal tissue and mortality of infected animals. Infections of mouse intestinal cell cultures were then performed to determine whether this simpler model system's mRNA responses correlated to neonatal results and therefore be predictive of virulence of Aeromonas spp. Virulent aeromonads up-regulated transcripts in both models including multiple host defense gene products (chemokines, regulation of transcription and apoptosis, cell signaling). Avirulent species exhibited little or no host response in neonates. Mortality results correlated well with both bacterial dose and average fold change of up-regulated transcripts in the neonatal mice. Conclusions: Cell culture results were less discriminating but showed promise as potentially being able to be predictive of virulence. Jun oncogene up-regulation in murine cell culture is potentially predictive of Aeromonas virulence. Significance and Impact of the Study: Having the ability to determine virulence of waterborne pathogens quickly would potentially assist public health officials to rapidly assess exposure risks. Keywords: Aeromonas; Virulence; Gene expression; Host response
Project description:Aims: To assess the virulence of multiple Aeromonas spp. using two models, a neonatal mouse assay and a mouse intestinal cell culture. Methods and Results: Transcriptional responses to both infection models were evaluated using microarrays. After artificial infection with a variety of Aeromonas spp., mRNA extracts from the two models were processed and hydridized to murine microarrays to determine host gene response. Definition of virulence was determined based on host mRNA production in murine neonatal intestinal tissue and mortality of infected animals. Infections of mouse intestinal cell cultures were then performed to determine whether this simpler model system's mRNA responses correlated to neonatal results and therefore be predictive of virulence of Aeromonas spp. Virulent aeromonads up-regulated transcripts in both models including multiple host defense gene products (chemokines, regulation of transcription and apoptosis, cell signaling). Avirulent species exhibited little or no host response in neonates. Mortality results correlated well with both bacterial dose and average fold change of up-regulated transcripts in the neonatal mice. Conclusions: Cell culture results were less discriminating but showed promise as potentially being able to be predictive of virulence. Jun oncogene up-regulation in murine cell culture is potentially predictive of Aeromonas virulence. Significance and Impact of the Study: Having the ability to determine virulence of waterborne pathogens quickly would potentially assist public health officials to rapidly assess exposure risks. Experiment Overall Design: Two infection models were assessed, live, whole animals (neonatal Swiss Webster mice) and a murine small intestinal cell culture. Biological replicates (n=5) were infected with different Aeromonas species/strains and compared to uninfected controls.
Project description:Plants have evolved a sophisticated defense system to survive under natural drought conditions. MicroRNAs (miRNA) are small noncoding RNAs that act as a post-transcriptional regulator in the environmental stress response and developmental process. Although many studies have reported the involvement of the miRNAs in drought response, molecular mechanisms by which miRNAs confer drought tolerance remain elusive. Here, we show that MIR171f, a member of MIR171 gene family, is mainly expressed in response to drought stress and regulate transcript levels of SCARECROW-LIKE6-I (SCL6-I) and SCL6-II. The SCL6 genes are known to be involved in shoot branching and flag leaf morphology. The MIR171f-overexpressing (MIR171f-OE) transgenic plants showed reduced drought symptoms as compared with non-transgenic (NT) control plants under both field drought and PEG-mediated dehydration stress conditions. Transcriptome analysis using the MIR171f-OE and mir171f-K/O mutants revealed that MIR171f regulates the expression of flavonoid biosynthesis genes, consequently leading to drought tolerance. Flavonoid biosynthesis genes were up-regulated in MIR171f-OE plants as compared with NT control plants under both normal and drought conditions. Together, our findings demonstrated that MIR171f plays an important role in plant drought-tolerance mechanism by regulating transcript levels of SCL6-I and SCL6-II.
Project description:High temperature and drought are the primary yield-limiting environmental constraints for staple food crops. Heat shock transcription factors (HSF) terminally regulate the plant abiotic stress responses to maintain growth and development under extreme environmental conditions. HSF genes of Subclass A2 predominantly express under heat stress (HS) and activate the transcriptional cascade of defense-related genes. In this study, a highly heat-inducible HSF, HvHSFA2e was constitutively expressed in barley (Hordeum vulgareL.) to investigate its role in abiotic stress response and plant development. Transgenic barley plants displayed enhanced heat and drought tolerance in terms of increased chlorophyll content, improved membrane stability, reduced lipid peroxidation, and less accumulation of ROS in comparison to wild-type (WT) plants. Transcriptome analysis revealed that HvHSFA2e positively regulates the expression of abiotic stress-related genes encoding HSFs, HSPs, and enzymatic antioxidants, contributing to improved stress tolerance in transgenic plants. The major genes of ABA biosynthesis pathway, flavonoid, and terpene metabolism were also upregulated in transgenics. Our findings show that HvHSFA2e mediated upregulation of heat-responsive genes, modulation in ABA and flavonoid biosynthesis pathways enhance drought and heat stress tolerance.