Project description:Spinach (Spinacia oleracea L.) is an economically important and globally consumed popular leafy vegetable that is heat-sensitive. Heat stress caused by global climate change is one of the primary deleterious elements limiting spinach production worldwide. Little work has been done to explore the heat-responsive mechanisms of spinach under high temperature-induced stress. In the present study, we used iTRAQ-based proteomic and transcriptomic approaches to investigate physiological, metabolic, and proteomic responses of spinach in response to day / night temperature of 35°C / 25°C compared to 20°C / 15°C for 4 days. A total of 3,543 differentially expressed genes (DEGs) were detected using transcriptome sequencing, of which 2,086 DEGs were downregulated and 1,457 were upregulated. The DEGs were mainly involved in superoxide dismutase activity, catalase, and peroxidase activity. A total of 3,246 differentially abundant proteins were detected using iTAQ-based quantitative proteomic approach, from which 567 differentially expressed proteins (DEPs) (277 upregulated and 290 downregulated) were identified. DEPs were mainly assigned to pathways related to metabolism, signal transduction, protein degradation, defense, and antioxidant. Four genes - superoxide dismutase (SOD, LOC110788339), catalase (CAT, LOC110790286), peroxidase (POD, LOC110775253), and heat shock protein (HSP, LOC110799288) - were validated using quantitative real-time PCR (qRT-PCR) to verify the proteomic and transcriptomic analyses, showing different transcriptional and translational expression levels. The findings of this study provide a fundamental understanding of the metabolic pathways and biological processes that control adaptation to heat stress in spinach, and provide novel insight into the development of heat-tolerant spinach.
Project description:Purpose: To examine the gene expression within the spinach root tissues as a response to exposure to nanoparticles. Methods: Sequenced reads were processed using CLC Genomics Workbench 7.0. The reads were trimmed based on quality, length and ambiguity. Resulting reads were assembled into transcript assemblies. Sequence reads were mapped back to the constructed transcriptome. TAs were BLAST searched against a local blast database of coding sequences of Arabidopsis thaliana. Statistical analysis was performed using Baggerley’s test. Transcript assemblies were tested for gene enrichment using GO annotations and the functional categories were determined. MapMan was used to visualize gene expression data of TAs and study the biological pathways. Results: De novo assembly of the trimmed reads yielded 147,733 Transcript Assemblies (TA) with an average length of 645 bp. Largest TA was 16,379 bp. Approximately 89% of the quality trimmed reads from the different samples mapped successfully to the assembly reference. Gene expression data for spinach TAs homologous to Arabidopsis genes show upregulation of protein degradation pathways in the nano-ZnO treatment compared to the non-nanoZnO, this upregulation is coupled with a down regulation of the genes in the protein synthesis pathways crucial role in the spinach plant responses to ZnO nanoparticle exposure. Genes associated (REDOX, signaling and transcription factors) with responses to stresses (both abiotic and biotic) were upregulated upon exposure to ZnO nanoparticles. Additionally genes in biosynthesis pathways of jasmonate and gibberellins genes were up-regulated upon exposure to ZnO nanoparticles in spinach. Conclusions: A de novo transcriptome was developed for spinach. When spinach plants were exposed to ZnO nanoparticles, they seem to sense the nanoparticles similarly to external chemicals or pathogens and induced production of reactive oxygen species. Hormone signaling pathways were activated leading to the induced expression of hormones with different roles in defense.