Project description:Global warming and heat stress belong to the most critical environmental challenges to agriculture worldwide, causing severe losses of major crop yields. In present study we report that the endophytic bacterium Enterobacter sp. SA187 protects Arabidopsis thaliana to heat stress. To understand the mechanisms at molecular level we performed RNA-seq
Project description:Global warming has become a critical challenge to food safety, causing severe yield losses of major crops worldwide. Here, we report that the endophytic bacterium Enterobacter sp. SA187 induces thermotolerance of crops in a sustainable manner. Microbiome diversity of wheat plants is positively influenced by SA187 in open field agriculture, indicating that beneficial microbes can be a powerful tool to enhance agriculture in open field agriculture.
Project description:We show for soil bacterium Enterobacter soli LF7 (synonym Enterobacter asburiae LF7a) that possession of a iac (indole 3-acetic acid catabolic) gene cluster is causatively linked to the ability to utilize the plant hormone indole 3-acetic acid (IAA) as a carbon and energy source. Genome-wide transcriptional profiling by mRNA sequencing revealed that these iac genes chromosomally arranged as iacHABICDEFG and coding for the transformation of IAA to catechol, were the most highly induced (>29-fold) among the relatively few (<1%) differentially expressed genes in response to IAA. Also highly induced and immediately downstream of the iac cluster were genes for a Major Facilitator Superfamily protein (mfs) and enzymes of the β-ketoadipate pathway (pcaIJD-catBCA), which channels catechol into central metabolism. This entire iacHABICDEFG-mfs-pcaIJD-catBCA gene set was constitutively expressed in a iacR deletion mutant, confirming the role of iacR, annotated as coding for a MarR-type regulator and located upstream of iacH, as a repressor of iac gene expression. The research described here was funded from grants #2010-03544 and #2013-02075 awarded to JHJL by the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) Agriculture and Food Research Initiative (AFRI)
Project description:Background: Enterobacter cloacae complex (ECC) is a common opportunistic pathogen and is responsible for causing various infections in humans. Owing to its inducible chromosomal AmpC β-lactamase (AmpC), ECC is inherently resistant to the 1st- and 2nd- generation cephalosporins. However, whether β-lactams antibiotics enhance ECC resistance remains unclear. Results: In this study, we found that subinhibitory concentrations (SICs) of cefazolin (CFZ) and imipenem (IMP) can advance the expression of AmpC and enhance its resistance towards β-lactams through NagZ in Enterobacter cloacae (EC). Further, AmpC manifested a substantial upregulation in EC in response to SICs of CFZ and IMP. In nagZ knockout EC (ΔnagZ), the resistance to β-lactam antibiotics was rather weakened and the effect of CFZ and IMP on AmpC induction was completely abrogated. NagZ ectopic expression can rescue the induction effects of CFZ and IMP on AmpC and increase ΔnagZ resistance. More importantly, CFZ and IMP have the potential to induce the expression of AmpR's target genes in a NagZ-dependent manner. Conclusions: Our findings suggest that NagZ is a critical determinant for CFZ and IMP to promote AmpC expression and resistance and that CFZ and IMP should be used with caution since they may aggravate ECC resistance. At the same time, this study further improves our understanding of resistance mechanisms in ECC.
