Project description:BACKGROUND: Western flower thrips are considered the major insect pest of horticultural crops worldwide, causing economic and yield loss to Solanaceae crops. The eggplant (Solanum melongena L.) resistance against thrips remains largely unexplored. This work aims to identify thrips-resistant eggplants and dissect the molecular mechanisms underlying this resistance using the integrated metabolomic and transcriptomic analyses of thrips-resistant and -susceptible cultivars. RESULTS: We developed a micro-cage thrips bioassay to identify thrips-resistant eggplant cultivars, and highly resistant cultivars were identified from wild eggplant relatives. Metabolomic profiles of thrips-resistant and -susceptible eggplant were compared using the gas chromatography-mass spectrometry (GC-MS)-based approach, resulting in the identification of a higher amount of quinic acid in thrips-resistant eggplant compared to the thrips-susceptible plant. RNA-sequencing analysis identified differentially expressed genes (DEGs) by comparing genome-wide gene expression changes between thrips-resistant and -susceptible eggplants. Consistent with metabolomic analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs revealed that the starch and sucrose metabolic pathway in which quinic acid is a metabolic by-product was highly enriched. External application of quinic acid enhances the resistance of susceptible eggplant to thrips. CONCLUSION: Our results showed that quinic acid plays a key role in the resistance to thrips. These findings highlight a potential application of quinic acid as a biocontrol agent to manage thrips and expand our knowledge to breed thrips-resistant eggplant.
Project description:Bacteria in the genus Pantoea (family Enterobacteriales) are metabolically diverse, cosmopolitan, and form a wide range of interactions with eukaryotic hosts including plants, fungi, insects and humans. Several Pantoea species have pathogenic interactions with plants. Strains of at least four Pantoea species (P. ananatis, P. allii, P. stewartii subsp. indologenes and P. agglomerans) are known to cause onion center rot disease. P. ananatis is very unusual among characterized bacterial plant pathogens. Virulence factors that distinguish onion-virulent and non-virulent P. ananatis have only recently been described. Most bacterial plant pathogens are dependent on specialized virulence protein secretion systems for pathogenicity. However, to cause plant cell death, P. ananatis instead requires the HiVir (High Virulence) proposed secondary metabolite synthetic cluster for an as of yet undescribed phosphonate compound. P. allii is also pathogenic on onion but, surprisingly, lacks the HiVir gene cluster associated with onion-virulent P. ananatis. P. allii carries a completely distinct predicted phosphonate compound synthetic cluster which has, interestingly, also been identified in P. stewartiii subsp indologenes that have expanded their host range from millet onto onions. We obtained the cell pellet metabolite profiles of P. ananatis PNA 97-1, the P. allii type strain LMG 24248, and the two corresponding biosynthetic mutant strains lacking a key gene (pepM) for the synthesis of phosphonate compounds. Understanding the unique chemistry of onion-virulent Pantoea will yield important insights into novel frameworks for plant- pathogen interactions.
The work (proposal:https://doi.org/10.46936/10.25585/60001193) conducted by the U.S. Department of Energy Joint Genome Institute (https://ror.org/04xm1d337), a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy operated under Contract No. DE-AC02-05CH11231.
Project description:Background: Pantoea ananatis LMG 2665T synthesizes and utilizes acyl homoserine lactones (AHLs) for signaling. In this strain, short chain AHLs (C4 to C8) are produced by the EanI/R quorum sensing (QS) system that is involved in pathogenicity and biofilm formation. The complete set of genes regulated by the EanI/R system in P. ananatis LMG 2665T is still not fully known. In the present study, RNA-seq was used to analyze the transcriptome profiles controlled by the EanI/R system in this strain by comparing the wild type strain and its QS mutant 2665T ean∆I/R during lag and log stages. The RNA seq data was validated by RT qPCR. Results: The results showed that the EanI/R regulon in P. ananatis LMG 2665T comprised 144 genes, constituting 3.3% of the whole transcriptome under the experimental conditions in this study. The majority of genes regulated by the EanI/R system included genes for flagella assembly, bacterial chemotaxis, pyruvate metabolism, two component system, metabolic pathways, microbial metabolism and biosynthesis of secondary metabolites. Conclusions: This is the first study to identify the EanI/R QS regulon in P. ananatis LMG 2665T. Functional analysis of genes regulated the EanI/R system in LMG 2665T could help unveil genes that play a vital role in pathogenesis and survival strategies of this pathogen.
Project description:Purpose: This study is designed to identify genes and processes that are differentially regulated in corn when it is grown with or without weeds through the entire critical weed free period (to V8) or when weeds were removed early in the critical weed free period (at V4) and the plants were allowed to recover until V8. Methods: Corn was grown as described above in field plots near Brookings SD in 2007 and 2008 and RNA was extracted from the top-most leaf tips from four plants per treatment plot. Unidirectional cDNA illumina sequencing libraries were constructed for each sample (pooled leaf tips from the given plot), and were sequenced (some samples were paired end sequenced and some were single end sequenced - all 100 bases for PE and SE reads), quality trimmed, and analyzed using the Tuxedo suite of programs for SE reads of the forward read libraries for each sample. Results: We identified a small number of genes that were differentially expressed in both years. More importantly, gene set enrichment analysis of the data determined that weeds, when present through the critical weed free period impacted phytochrome signaling, defense responses, photosynthetic processes, oxidative stress responses, and various hormone signaling processes. When weeds were removed at V4 and the plants allowed to recover until V8, the weeds still imprinted impacts on phytochrome signaling, oxidative stress, and defense responses. Thus, it appears that weeds presence through the early portion of the critical weed free period, even after removal, induced processes that reduce corn growth and yield that lasted at least through V8. Conclusions: This study represents the first investigation of the impact of the lasting effects of weeds during the early critical weed free period on the transcriptome of corn, and provides additional data on the impact of weeds through the critical weed free period that augments and confirms much of what was observed in similar microarray studies.
Project description:We analyzed the interaction between Arabidopsis and western flower thrips (Frankliniella occidentalis), which are one of the most serious insect pests of cultivated plants. A total of 1.2K potential biotic and abiotic stress-related genes were selected from the genes covered by the Arabidopsis 7K array (RIKEN, Japan) and Arabidopsis oligo microarray (Agilent Technologies, USA) for this study. The 21- day-old plants were feeded by western flower thrips in an acryl cylinder chamber with air ventilation windows covered with a fine mesh. Leaves were harvested several time after the feeding. Our results indicate that JA plays an important role in Arabidopsis in terms of response to, and tolerance against, thrip feeding.
Project description:In the current study, we sought to elucidate the plant-mediated mechanisms underlying the interaction between TSWV and its insect vector, F. occidentalis in the plant host, tomato, Solanum lycopersicum L. We performed replicated greenhouse and laboratory experiments to confirm that TSWV altered vector performance and behavior in ways that improved virus transmission. To characterize plant molecular mechanisms, microarray analysis was done in tomato plants that were systemically-infected with TSWV, infested with thrips, or both TSWV and thrips using Affymetrix Tomato GeneChip®. The tomato microarray chip includes many defense- and stress-related genes and genes related to chloroplast function, cell wall modification, and protein synthesis which we hypothesized would be involved in TSWV-vector interaction.
Project description:Research conducted, including the rationale: Weeds reduce yield in soybeans through incompletely defined mechanisms. The effects of weeds on the soybean transcriptome were evaluated in field conditions during four separate gR1.fastqing seasons. Methods: RNASeq data were collected from 6 biological samples of soybeans gR1.fastqing with or without weeds. Weed species and the methods to maintain weed free controls varied between years to mitigate treatment effects and to allow detection of general soybeans weed responses. Key results: Soybean plants were not visibly nutrient or water stressed. We identified 55 consistently down-regulated genes in weedy plots. Many of the down-regulated genes were heat shock genes. Fourteen genes were consistently up-regulated. Several transcription factors including a PHYTOCHROME INTERACTING FACTOR 3-like gene (PIF3) were included among the up-regulated genes. Gene set enrichment analysis indicated roles for increased oxidative stress and jasmonic acid signaling responses during weed stress. Main conclusion: The relationship of this weed-induced PIF3 gene to genes involved in shade avoidance responses in arabidopsis provide evidence that this gene may be important in the response of soybean to weeds. These results suggest the weed-induced PIF3 gene will be a target for manipulating weed tolerance in soybean.
Project description:Research conducted, including the rationale: Weeds reduce yield in soybeans through incompletely defined mechanisms. The effects of weeds on the soybean transcriptome were evaluated in field conditions during four separate gR1.fastqing seasons. Methods: RNASeq data were collected from 6 biological samples of soybeans gR1.fastqing with or without weeds. Weed species and the methods to maintain weed free controls varied between years to mitigate treatment effects and to allow detection of general soybeans weed responses. Key results: Soybean plants were not visibly nutrient or water stressed. We identified 55 consistently down-regulated genes in weedy plots. Many of the down-regulated genes were heat shock genes. Fourteen genes were consistently up-regulated. Several transcription factors including a PHYTOCHROME INTERACTING FACTOR 3-like gene (PIF3) were included among the up-regulated genes. Gene set enrichment analysis indicated roles for increased oxidative stress and jasmonic acid signaling responses during weed stress. Main conclusion: The relationship of this weed-induced PIF3 gene to genes involved in shade avoidance responses in arabidopsis provide evidence that this gene may be important in the response of soybean to weeds. These results suggest the weed-induced PIF3 gene will be a target for manipulating weed tolerance in soybean. Samples were collected from two treatments ("Control" and "Weedy") with six biological replicates (2008, 2009, and twop each for 2010 and 2011) for each treatment.