Project description:Summary: Salmonella enterica serovar Typhimurium strain 14028s transcriptome response to lettuce medium (LM) and lettuce root exudates (LX) to minimal medium (MM). Purpose: Salmonella mRNA profile, when grown in different media was compared to minimal medium to reveal environment specific transcriptional changes. Methods: mRNA profiles were generated using Illumina HiSeq in triplicates. The sequences were analysed using Bowtie2 followed by Cufflinks.
Project description:Chitin soil amendment is known to improve soil quality, plant growth and plant stress resilience, but the underlying mechanisms are not well understood. In this study, we monitored chitin’s effect on lettuce physiology every two weeks through an eight-week growth period, analyzed the early transcriptional reprogramming and related metabolomic changes of lettuce, in response to crab chitin treatment in peat-based potting soil. In commercial growth conditions, chitin amendment still promoted lettuce growth, increased chlorophyll content, the number of leaves and crop head weight from week six. The flavonoid content in lettuce leaves was altered as well, showing an increase at week two but a decrease from week six. Transcriptomic analysis showed that over 300 genes in lettuce root were significant differentially expressed after chitin soil treatment. Gene Ontology-term (GO) enrichment analysis revealed statistical overrepresentation of GO terms linked to photosynthesis, pigment metabolic process and phenylpropanoid metabolic process. Further analysis of the differentially expressed genes (DEGs) showed that the flavonoid pathway is mostly upregulated whereas the bifurcation of upstream phenylpropanoid pathway towards lignin biosynthesis is mostly downregulated. Metabolomic analysis revealed the upregulation of salicylic acid, chlorogenic acid, ferulic acid, and p-coumaric acid in chitin treated lettuce seedlings. These phenolic compounds mainly influence the phenylpropanoid biosynthesis pathway and may play important roles in plant defense reactions. Our results suggest that chitin soil amendments might activate induced resistance by priming lettuce plants and promote lettuce growth via transcriptional changes.
Project description:Increasing evidence of Pseudomonas aeruginosa on fresh plant-based foods raises food safety concerns. While internalization of pathogens such as Salmonella enterica in vegetables such as lettuce is well documented, corresponding data for P. aeruginosa are lacking. Moreover, climate change-associated temperature shifts may influence the plant microbiota and the presence of human pathogens. This study investigates the internalization and temperature-dependent gene expression of P. aeruginosa PAO1 on green oak leaf lettuce as a model system. For this purpose, oak leaf lettuce was cultivated in soil inoculated with P. aeruginosa PAO1_sfGFP_UHH07, and internalization was analyzed using confocal laser scanning microscopy. Temperature-dependent transcriptomic changes of P. aeruginosa PAO1 were assessed by analyzing differentially expressed genes following plant inoculation and incubation at 18 and 22 °C, respectively. P. aeruginosa PAO1 is capable of internalizing into the roots of oak leaf lettuce, but a translocation into leaves was not detected. Transcriptomic analyses showed that a moderate temperature increase shifts bacterial gene expression, with virulence genes upregulated at 22 °C and persistence-associated genes predominating at 18 °C. These results show that temperature influences the persistence and pathogenic potential of P. aeruginosa present on oak leaf lettuce, highlighting potential impacts of climate change on food safety.
Project description:Lettuce is one of most consumed vegetables globally. This crop is susceptible to abiotic stresses. To understand the molecular mechanisms of stress response in lettuce, global transcriptome analysis was conducted. This analysis revealed distinctive temporal expression patterns among the stress-regulated genes in lettuce plants exposed to abiotic stresses
Project description:The use of new natural eco-sustainable products is becoming an interesting option in order to reduce the use of chemical fertilizers and increase crop yields. Seaweed extracts are gained major attention as plant biostimulants due to their positive effect on plant-growth as well as on improving plants’ tolerance against abiotic stresses. Among the horticulture crops, lettuce (Lactuca sativa L.) is a major fresh vegetable crop in the Mediterranean area, which often requires the use of natural biostimulants to improve both the quantity and quality of production. The aim of this work was to assess the effect of either Chlorella vulgaris or Scenedesmus quadricauda extracts on lettuce seedlings (Lactuca sativa L.) by motoring the induced transcriptomic modifications using a RNASeq approach. The results showed that both C. vulgaris and S. quadricauda extracts positively influence the growth of lettuce seedlings. However, a higher reprogramming of the gene expression occurred in the case of C. vulgaris treatment than in S. quadricauda extract. Considering the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway functional enrichments, the main KEGG terms are in the “Biosynthesis of secondary metabolites”, “Metabolic pathways”, “Carbon metabolism” and “Biosynthesis of amino acids” categories. This study lays the basis for understanding the mechanisms and processes triggered by the use of microalgal extracts, which can represent an easier-to-handle and cheaper method for an eco-sustainable cultivation of lettuce plants than the application of chemicals.
Project description:Plants acquire essential elements from inherently heterogeneous soils, in which phosphate and iron availabilities vary. Consequently, plants developed adaptive strategies to cope with low iron and low phosphate levels, including alternation between root growth enhancement and attenuation. How this adaptive response is achieved remains unclear. Here, we found that low iron accelerates the root growth of Arabidopsis thaliana by activating brassinosteroid signaling, whereas low-phosphate-induced high iron accumulation inhibited it. Altered hormone signaling intensity also modulated iron accumulation in the root elongation and differentiation zones, constituting a feedback response between brassinosteroid and iron. Surprisingly, the early effect of low iron levels on root growth required the brassinosteroid receptor but the hormone ligand was negligible. The brassinosteroid receptor inhibitor BKI1, the transcription factors BES1/BZR1 and the ferroxidase LPR1, stood at the base of this feedback loop. Hence, shared brassinosteroid and iron regulatory components link nutrient status to root morphology, thereby driving the adaptive response.