Host and pathogen gene expression during early infection of soybean seedlings by Phytophthora sojae, analyzed by ABI Solid RNA sequencing
ABSTRACT: Hypocotyls of soybean (Glycine max) seedlings of cultivar Williams were inoculated with mycelia of the oomycete pathogen Phytophthora sojae grown in liquid V8 medium or the hypocotyls were mock inoculated. After 12 hours, the sites of inoculation were excised from the hypocotyls and frozen for RNA extraction. Phytophthora sojae mycelia used for inoculation was saved for RNA extraction also Overall design: Four replicate experiments were conducted. Each replicate consisted of 30 P. sojae-inoculated or mock-inoculated hypocotyls, as well as a sample of the P. sojae mycelia used for the 30 inoculations
INSTRUMENT(S): AB SOLiD System 3.0 (Glycine max; Phytophthora sojae)
Project description:Total RNA extracted from Phytophthora sojae (strain P6497) and infected soybean hypocotyls (cultivar Harosoy) provided template for synthesis of cDNA probes used in the microarray hybridizations. Infected plant hypocotyls were sampled 6 h, 12 h, 24 h, and 48 h after inoculation. Mycelia were grown on synthetic media (H&S) or vegetable juice media (V8). Zoospores were sampled at 0 h, 2 h and 6 h after inducing encystment and germination by agitation. We used microarrays to characterize gene expression patterns in the root rot pathogen Phytophthora sojae and its host Glycine max. Keywords: infection time course, zoospore germination time course, media formulation response Overall design: 28 samples from 9 treatments; 2 to 5 biological replicates per treatment.
Project description:Total RNA extracted from Phytophthora sojae (strain P6497) and infected soybean hypocotyls (cultivar Harosoy) provided template for synthesis of cDNA probes used in the microarray hybridizations. Infected plant hypocotyls were sampled 6 h, 12 h, 24 h, and 48 h after inoculation. Mycelia were grown on synthetic media (H&S) or vegetable juice media (V8). Zoospores were sampled at 0 h, 2 h and 6 h after inducing encystment and germination by agitation. We used microarrays to characterize gene expression patterns in the root rot pathogen Phytophthora sojae and its host Glycine max. Keywords: infection time course, zoospore germination time course, media formulation response 28 samples from 9 treatments; 2 to 5 biological replicates per treatment.
Project description:Early and accurate detection of the causal pathogen Phytophthora sojae is crucial for effective prevention and control of root and stem rot and seedling damping-off of soybean. In the present study, a novel isothermal amplification assay was developed for detecting P. sojae. This 25 min assay included a two-step approach. First, a pair of novel primers, PSYPT-F and PSYPT-R were used to amplify a specific fragment of the Ypt1 gene of P. sojae in a 20 min recombinase polymerase amplification (RPA) step. Second, lateral flow dipsticks (LFD) were used to detect and visualize RPA amplicons of P. sojae within 5 min. This RPA-LFD assay was specific to P. sojae. It yielded negative detection results against 24 other Phytophthora, one Globisporangium, and 14 fungal species. It was also found to be sensitive, detecting as low as 10 pg of P. sojae genomic DNA in a 50-?L reaction. Furthermore, P. sojae was detected from artificially inoculated hypocotyls of soybean seedlings using this novel assay. In a comparative evaluation using 130 soybean rhizosphere samples, this novel assay consistently detected P. sojae in 55.4% of samples, higher than other three methods, including loop-mediated isothermal amplification (54.6%), conventional PCR (46.9%), and leaf-disc baiting (38.5-40.0%). Results in this study indicated that this rapid, specific, and sensitive RPA-LFD assay has potentially significant applications to diagnosing Phytophthora root and stem rot and damp-off of soybean, especially under time- and resource-limited conditions.
Project description:Examination of soybean hypocotyls, G. max cv. Harosoy (Rps7), at 3, 6, 12, 24 and 48 hours after inoculation with P. sojae, race 2, isolate P6497 Patterns of Gene Expression Upon Infection of Soybean Plants by Phytophthora sojae. P. Moy, D. Qutob, B. P. Chapman, I. Atkinson, and M. Gijzen. Pages 1051-1062. Publication no. M-2004-0728-01R. Molecular Plant-Microbe Interactions, October 2004, Volume 17, Number 10. Keywords: time-course
Project description:Small RNAs, including microRNAs (miRNAs) and small interfering RNAs (siRNAs) are negative regulators to target endogenous genes and repetitive sequences in plants. Although miRNAs and trans-acting or phased siRNAs (tasiRNAs or phasiRNAs) were found to target hundreds of disease related genes in Medicago, their role in plant-pathogen interactions in the legumes, particularly the R genes mediated interaction of soybean and the pathogen Phytophthora sojae is poorly understood. A deep sequencing was performed on nine soybean near isogenic lines (NILs) each carrying an Rps (Resistance to Phytophthora sojae) gene and their recurrent parent “Williams”, with sampling performed both pre- and post-inoculation with P. sojae. From these data, 44 known MIRNA loci with new miRNA variants, 78 novel miRNAs corresponding to 108 precursors, and 208 phasiRNA-producing (PHAS) loci were identified. Our data showed that overall the expression levels of miRNAs, phasiRNAs and siRNAs were extensively down-regulated after pathogen-inoculation. Moreover, the down-regulation levels in the nine resistant NILs were significantly higher than that detected in the susceptible Williams, and variations of small RNA expression within the resistant NILs were also observed, suggesting the molecular responses of different Rps lines are distinct. Surprisingly, the expression level changes of 21-nt phasiRNAs were significantly positively correlated with that of the corresponding mRNA level of the PHAS genes, suggesting the cascade effects of miRNA triggers on the downstream PHAS genes and phasiRNAs. Our data provided a comprehensive picture regarding small RNA based regulation of target genes, particularly NB-LRRs, involved in the responses to the pathogen. 20 samples were sequenced, 10 inoculated with P. sojae, the other 10 were mock-inoculated
Project description:BACKGROUND:Silicon (Si) is known to protect against biotrophic and hemibiotrophic plant pathogens; however, the mechanisms by which it exerts its prophylactic role remain unknown. In an attempt to obtain unique insights into the mode of action of Si, we conducted a full comparative transcriptomic analysis of soybean (Glycine max) plants and Phytophthora sojae, a hemibiotroph that relies heavily on effectors for its virulence. RESULTS:Supplying Si to inoculated plants provided a strong protection against P. sojae over the course of the experiment (21 day). Our results showed that the response of Si-free (Si-) plants to inoculation was characterized early (4 dpi) by a high expression of defense-related genes, including plant receptors, which receded over time as the pathogen progressed into the roots. The infection was synchronized with a high expression of effectors by P. sojae, the nature of which changed over time. By contrast, the transcriptomic response of Si-fed (Si+) plants was remarkably unaffected by the presence of P. sojae, and the expression of effector-coding genes by the pathogen was significantly reduced. CONCLUSION:Given that the apoplast is a key site of interaction between effectors and plant defenses and receptors in the soybean-P. sojae complex, as well as the site of amorphous-Si accumulation, our results indicate that Si likely interferes with the signaling network between P. sojae and the plant, preventing or decreasing the release of effectors reaching plant receptors, thus creating a form of incompatible interaction.
Project description:Soybean is one of the most important economic and oil crops across the world. Phytophthora root rot (PRR), caused by <i>Phytophthora sojae</i> (<i>P. sojae</i>), is a major disease in most soybean-growing regions worldwide. Here, we investigated metabolic changes in hypocotyls of two soybean lines, Nannong 10-1 (resistant line, R) and 06-070583 (susceptible line, S), at two time points (12 and 36 hpi) after <i>P. sojae</i> infection and metabolic differences between the R line and the S line. In total, 90 differentially accumulated metabolites (DAMs) were identified after <i>P. sojae</i> infection; the levels of 50 metabolites differed between the R line and the S line. There are 28 DAMs that not only differentially accumulated between the R line and the S line but also differentially accumulated after <i>P. sojae</i> infection. Based on the changes of these DAMs in response to <i>P. sojae</i> infection in different lines and at different timepoints, and the differences in the contents of these DAMs between the R line and the S line, we speculated that DAMs, including sugars (monosaccharides and oligosaccharides), organic acids (oxalic acid, cumic acid), amino acid derivatives, and other secondary metabolites (mannitol, octanal, hypoxanthine, and daidzein etc.) may participate in the metabolic-level defense response of soybean to <i>P. sojae</i>. In this study, an integrated pathway-level analysis of transcriptomics (obtained by RNA-Seq) and metabolomics data illustrated the poor connections and interdependencies between the metabolic and transcriptional responses of soybean to <i>P. sojae</i> infection. This work emphasizes the value of metabolomic studies of plant-pathogen interactions and paves the way for future research of critical metabolic determinants of the soybean-<i>P. sojae</i> interaction.
Project description:Phytophthora sojae causes soybean root and stem rot, resulting in an annual loss of 1-2 billion US dollars in soybean production worldwide. A proteomic technique was used to determine the effects on soybean hypocotyls of infection with P. sojae.In the present study, 46 differentially expressed proteins were identified in soybean hypocotyls infected with P. sojae, using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization tandem time of flight (MALDI-TOF/TOF). The expression levels of 26 proteins were significantly affected at various time points in the tolerant soybean line, Yudou25, (12 up-regulated and 14 down-regulated). In contrast, in the sensitive soybean line, NG6255, only 20 proteins were significantly affected (11 up-regulated and 9 down-regulated). Among these proteins, 26% were related to energy regulation, 15% to protein destination and storage, 11% to defense against disease, 11% to metabolism, 9% to protein synthesis, 4% to secondary metabolism, and 24% were of unknown function.Our study provides important information on the use of proteomic methods for studying protein regulation during plant-oomycete interactions.
Project description:Phytophthora ramorum and Phytophthora sojae are destructive plant pathogens. P. sojae has a narrow host range, whereas P. ramorum has a wide host range. A global proteomics comparison of the vegetative (mycelium) and infective (germinating cyst) life stages of P. sojae and P. ramorum was conducted to identify candidate proteins involved in host range, early infection, and vegetative growth. Sixty-two candidates for early infection, 26 candidates for vegetative growth, and numerous proteins that may be involved in defining host specificity were identified. In addition, common life stage proteomic trends between the organisms were observed. In mycelia, proteins involved in transport and metabolism of amino acids, carbohydrates, and other small molecules were up-regulated. In the germinating cysts, up-regulated proteins associated with lipid transport and metabolism, cytoskeleton, and protein synthesis were observed. It appears that the germinating cyst catabolizes lipid reserves through the beta-oxidation pathway to drive the extensive protein synthesis necessary to produce the germ tube and initiate infection. Once inside the host, the pathogen switches to vegetative growth in which energy is derived from glycolysis and utilized for synthesis of amino acids and other molecules that assist survival in the plant tissue.
Project description:Phytophthora sojae is an oomycete pathogen that causes the disease known as root and stem rot in soybean plants, frequently leading to massive economic damage. Additionally, P. sojae is increasingly being utilized as a model for phytopathogenic oomycete research. Despite the economic and scientific importance of P. sojae, the mechanism by which it penetrates the host roots is not yet fully understood. It has been found that oomycetes are not capable of penetrating the cell wall solely through mechanical force, suggesting that alternative factors facilitate breakdown of the host cell wall. Pectin methylesterases have been suggested to be important for Phytophthora pathogenicity, but no data exist on their role in the P. sojae infection process. We have scanned the newly revised version of the annotated P. sojae genome for the presence of putative pectin methylesterases genes and conducted a sequence analysis of all gene models found. We also searched for potential regulatory motifs in the promoter region of the proposed P. sojae models, and investigated the gene expression levels throughout the early course of infection on soybean plants. We found that P. sojae contains a large repertoire of pectin methylesterase-coding genes and that most of these genes display similar motifs in the promoter region, indicating the possibility of a shared regulatory mechanism. Phylogenetic analyses confirmed the evolutionary relatedness of the pectin methylesterase-coding genes within and across Phytophthora spp. In addition, the gene duplication events that led to the emergence of this gene family appear to have occurred prior to many speciation events in the genus Phytophthora. Our results also indicate that the highest levels of expression occurred in the first 24 hours post inoculation, with expression falling after this time. Our study provides evidence that pectin methylesterases may be important for the early action of the P. sojae infection process.