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: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.
Project description:Drought is a major limiting constraint to faba bean production worldwide, including Tunisia. However, molecular mechanisms underlying faba bean responses to drought stress are not well understood. In this context, transcriptome analysis by RNA-seq was performed to investigate drought-related genes and construct a network of faba bean drought stress response and tolerance. De novo assembly of the transcriptome generated 26,728 differentially expressed genes (DEGs). Of these, 13,920 were up-regulated and 12,808 down-regulated in faba bean drought-stressed leaves. Moreover, a total of 10,800 simple sequence repeats (SSRs) and 2130 transcription factors involved in major metabolic pathways including abscisic acid (ABA)-dependent and -independent signaling pathway were identified. GO, KOG and KEGG enrichment analyses revealed that these DEGs were involved in several important processes including photosynthesis, flavonoid biosynthesis, response to stimulus and abiotic stress, reactive oxygen species (ROS) scavengers, signal transduction, biosynthesis of secondary metabolites and transporters, suggesting the involvement of these important pathways in faba bean response to water deficit. Various stress proteins such as late embryogenesis abundant proteins (LEA), dehydrins (DHNs) and heat shock proteins (HSPs) have been identified and their expression was robustly upregulated in drought-stressed leaves, indicating their key contribution to drought response and adaptation by conferring protection and providing stability to faba bean plant cellular processes under water deficit. The reliability of the RNA-seq results was confirmed by the analysis of 10 randomly selected genes using qRT-PCR. Taken together, these findings help advancing our knowledge and can guide breeding programs aimed at improving the tolerance of faba bean to drought stress.