Project description:BACKGROUND: The tomato psyllid, Bactericera cockerelli Šulc (Hemiptera: Triozidae), is a pest of solanaceous crops such as tomato (Solanum lycopersicum L.) in the U.S. and vectors the disease-causing pathogen ‘Candidatus Liberibacter solanacearum’. Currently, the only effective strategies for controlling the diseases associated with this pathogen involve regular pesticide applications to manage psyllid population density. However, such practices are unsustainable and will eventually lead to widespread pesticide resistance in psyllids. Therefore, new control strategies must be developed to increase host-plant resistance to insect vectors. For example, expression of constitutive and inducible plant defenses can be improved through selection. Currently, it is still unknown whether psyllid infestation has any lasting consequences on tomato plant defense or tomato plant gene expression in general. RESULTS: To characterize the genes putatively involved in tomato defense against psyllid infestation, RNA was extracted from psyllid-infested and uninfested tomato leaves (Moneymaker) three weeks post-infestation. Transcriptome analysis identified 362 differentially expressed genes. These differentially expressed genes were primarily associated with defense responses to abiotic/biotic stress, transcription/translation, cellular signaling/transport, and photosynthesis. These gene expression changes suggested that tomato plants underwent a reduction in plant growth/health in exchange for improved defense against stress that was observable three weeks after psyllid infestation. Consistent with these observations, tomato plant growth experiments determined that the plants were shorter three weeks after psyllid infestation. Furthermore, psyllid nymphs had lower survival rates on tomato plants that had been previously psyllid infested. CONCLUSION: These results suggested that psyllid infestation has lasting consequences for tomato gene expression, defense, and growth.
Project description:‘Candidatus Liberibacter solanacearum’ (Lso) has emerged as a major pathogen of crops worldwide. This bacterial pathogen is transmitted by Bactericera cockerelli, tomato psyllid, to solanaceous crops. In this study, the transcriptome profiles of Solanum lycopersicum exposed to B. cockerelli infestation and to Lso infection were evaluated at one, two and four weeks following colonization and/or infection. Plant transcriptional response to Lso-negative B. cockerelli was different than plant responses to Lso-positive B. cockerelli. The comparative transcriptomes of plant responses to Lso-negative B. cockerelli revealed the up-regulation of genes associated with plant defenses regardless of the time-point. In contrast, the plant general responses to Lso-positive B. cockerelli and Lso-infection were temporally different. Infected plants down-regulated defense genes at week one while delayed the up-regulation of the defense genes to week two and four, time points in which early signs of disease development were also detected in the transcriptional response. For example, infected plants up-regulated carbohydrate metabolism genes which could be linked to the disruption of sugar distribution usually associated with Lso infection. Also, infected plants down-regulated photosynthesis genes potentially resulting in plant chlorosis, another symptom associated with Lso infection. Overall, this study highlights that S. lycopersicum plants induced different sets of genes in response to different stages of B. cockerelli infestation and Lso infection. This is the first transcriptome study of tomato responses to B. cockerelli and Lso, a first step in the direction of finding plant defense genes to enhance plant resistance.
Project description:Purpose: The tomato psyllid, Bactericera cockerelli Šulc (Hemiptera: Triozidae), is a pest of tomato (Solanum lycopersicum) and potato (S. tuberosum) in the U.S. and vectors the disease-causing pathogen ‘Candidatus Liberibacter solanacearum’. Plants undergo physiological, transcriptomic, or epigenetic changes in order to mount a stronger, faster response against secondary challenges by previously perceived threats. This is called defense ‘priming’ and it likely has an impact on vectored disease transmission. Currently, it is still unknown whether or not psyllid infestation has any lasting consequences for tomato gene expression or defense. To characterize the genes potentially involved in tomato priming against psyllids, RNA was extracted from psyllid-primed and uninfested tomato (Moneymaker) leaves three weeks after infestation. Methods: RNA was extracted and sequenced from plants three weeks after psyllid infestation. Plants were either left alone (Control or C) or infested with psyllids (Primed or J1). Libraries were developed using the TruSeq RNA Library Prep Kit v2. Sequencing was performed on the Illumina PE HiSeq 2500 v4 platform. Processed sequences were uploaded to the CyVerse Discovery Environment computational infrastructure where bioinformatic analysis was performed using the Tuxedo Suite 2 workflow. Results: Illumina HiSeq sequencing of tomato cDNA libraries produced 132,428,443 total reads that met FastQC quality control criteria. 94.6% of all reads mapped to vSL3.0 of the S. lycopersicum genome. CuffDiff2 analysis identified 310 differentially expressed genes (DEGs) between control and psyllid-primed plants (q-value <0.01). Conclusions: A week-long infestation by a small number of B. cockerelli had lasting consequences for gene expression in tomato plants. Homologs of the DEGs were associated with 1) defense against abiotic and biotic stress, 2) growth and development, and 3) components of plant biology indirectly involved in plant growth and development such as homeostasis, transcription/translation, and molecular transport.
Project description:To characterize the PTI response of tomato and the effect of the delivery of a subset of effectors, we performed an RNA-seq analysis of tomato Rio Grande prf3 leaves challenged with either the flgII-28 peptide or the following bacterial strains: Agrobacterium tumefaciens GV2260, Pseudomonas fluorescens 55, Pseudomonas putida KT2440, Pseudomonas syringae pv. tomato (Pst) DC3000, Pst DC3000 deltahrcQ-U deltafliC and Pst DC3000 deltaavrPto deltaavrPtoB. NOTE: Samples in SRA were assigned the same sample accession. This is incorrect as there are different samples, hence âSource Nameâ was replaced with new values. Comment[ENA_SAMPLE] contains the original SRA sample accessions.
Project description:Salt stress causes the quality change and significant yield loss of tomato. However, the resources of salt-resistant tomato were still deficient and the mechanisms of tomato resistance to salt stress were still unclear. In this study, the proteomic profiles of two salt-tolerant and salt-sensitive tomato cultivars were investigated to deciphered the salt-resistance mechanism of tomato and provide novel resources for tomato breeding. We found that there is an over-abundant proteins relevant to Nitrate and amino acids metabolisms in the Salt-tolerant cultivars. The significant increase in expression of proteins involved in Brassinolides and GABA biosynthesis were verified in salt-tolerant cultivars, strengthening the salt resistance of tomato. Meanwhile, salt-tolerant cultivars with higher abundance and activity of antioxidant-related proteins have more advantages in dealing with reactive oxygen species caused by salt stress. And the salt-tolerant cultivars had higher photosynthetic activity based on overexpression of proteins functioned in chloroplast, guaranteeing the sufficient nutrient for plant growth under salt stress. Furthermore, three key proteins were identified as important salt-resistant resources for breeding salt-tolerant cultivars, including Sterol side chain reductase, gamma aminobutyrate transaminase and Starch synthase. Our results provided series valuable strategies for salt-tolerant cultivars which can be used in future
Project description:RNA interference (RNAi) is a widely-used approach to generate virus-resistant transgenic crops. However, durability of RNAi-mediated resistance under extreme field conditions and side-effects of stable RNAi expression have not been thoroughly investigated. Here we performed field trials and molecular characterization of two RNAi-transgenic Solanum lycopersicum lines resistant to Tomato yellow leaf curl virus (TYLCV) disease, the major constraint for tomato cultivation in Cuba and worldwide. In order to determine potential impact of the hairpin RNA transgene expression on tomato genome expression and development, differences in the phenotypes and the transcriptome profiles between the transgenic and non-transgenic plants were examined. Transcriptome profiling revealed a common set of up- and down-regulated tomato genes, which correlated with slight developmental abnormalities in both transgenic lines.