Project description:Abscisic acid (ABA) regulates seed and bud dormancy. We show by forward and reverse genetic analysis that the tomato transcription factor SlZFP2 is required for release of bud and seed dormancy through negative regulation of ABA biosynthesis. We also demonstrated that ABA promotes growth and represses flowering in tomato both through transcriptional control on the florigen-encoding gene SINGLE FLOWER TRUSS (SFT) in tomato. To gain further insight on transcriptome changes by overexpresion of HA-SlZFP2, we sequenced two lines of p35S:HA-SlZFP2 in LA1589 background and their nontransgenic siblings on Illumina Hiseq2000 platform. Two homozygous transgenic lines 103 and 104 showing very similar phenotypes in flowering and branching were chosen for profiling gene expression via RNA sequencing. Their respective nontransgenic siblings were served as controls (103N and 104N).
Project description:Background: Tomato (Solanum lycopersicum) self-compatibility (SC) is defined as self-pollen tubes that can penetrate their own stigma, elongate in the style and fertilize their own ovules. Self-incompatibility (SI) is defined as self-pollen tubes that are prevented from developing in the style. To determine the influence of gene expression on style self-pollination, a transcriptome-wide comparative analysis of SC and SI tomato unpollinated/pollinated styles was performed using RNA-sequencing (RNA-seq) data. Results: Transcriptome profiles of 24-h unpollination (UP) and self-pollination (P) styles from SC and SI tomato species were generated using high-throughput next generation sequencing. From the comparison of SC self-pollinated and unpollinated styles, 1341 differentially expressed genes (DEGs) were identified, of which 753 were downregulated and 588 were upregulated. From the comparison of SI self-pollinated and unpollinated styles, 804 DEGs were identified, of which 215 were downregulated and 589 were upregulated. Nine gene ontology (GO) terms were enriched significantly in SC and 78 GO terms were enriched significantly in SI. A total of 105 enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified in SC and 80 enriched KEGG pathways were identified in SI, among which “Cysteine and methionine metabolism pathway” and “Plant hormone signal transduction pathway” were significantly enriched in SI. Conclusions: This study is the first global transcriptome-wide comparative analysis of SC and SI tomato unpollinated/pollinated styles. Advanced bioinformatic analysis of DEGs uncovered the pathways of “Cysteine and methionine metabolism” and “Plant hormone signal transduction”, which are likely to play important roles in the control of pollen tubes growth in SI species. 24-h unpollination (UP) and self-pollination (P) styles mRNA profiles from SC and SI tomato species were generated by deep sequencing, in triplicate, using Illumina Hiseq 2500 platform.
Project description:Ascorbic acid (AsA), important for plant cell protection against oxidative stresses, is useful for human health. Among vegetables, tomato is the most important specie due to its significant consumption at worldwide level. Although AsA metabolism has been characterized in detail, the genetic mechanisms controlling AsA accumulation in tomatoes are poorly understood. We used an introgression line (IL 10-1) containing a QTL inducing a reduced AsA accumulation in the fruit and carried out a comparative transcriptomic analysis in fruit tissues using a parental cultivar (M82) with normal fruit AsA levels as a reference. We identified 233 differentially expressed genes, indicating that AsA accumulation in IL 10-1 reflects modification in the peroxisomal metabolism and reduced glutathione biosynthesis. Evidences coming from the experiment suggest that the lower AsA accumulation in IL10-1 fruit is mainly achieved by increasing ROS generation through a NAD+-dependent isocitrate dehydrogenase and promoting an increase in aminoacid catabolism, which is driven by a stress response and may lead to lower glutathione pool. Overall design: Comparative microarray analysis between a tomato introgression line (IL10-1) expressing lower level of fruit ascorbic acid and its parental cultivar M82 (reference) was performed. In particular, samples were generated by pooling red-ripe fruit from the same plant and discarding the seeds, jelly parenchyma, columella and placenta tissues. Three plant replica were used for each line (IL10-1 and M82) and the experiment was replicated over two consecutive years.
Project description:Abscisic acid (ABA) regulates plant development and adaptation to environmental conditions. The ABA biosynthesis pathway in plants has been thoroughly elucidated; however, very few transcription factors directly regulating the expression of ABA biosynthetic genes have been identified. Here we show that the tomato (Solanum lycopersicum) zinc finger transcription factor SlZFP2, which is mainly expressed in developing fruits and axillary buds, negatively regulates ABA biosynthesis. Overexpression of SlZFP2 resulted in multiple phenotypic changes, including more branches, early flowering, delayed fruit ripening, lighter seeds and faster seed germination, whereas gene silencing by RNA interference (RNAi) caused poor fruit set and inhibited seed germination. Gene expression analysis showed that SlZFP2 represses ABA biosynthesis mainly through downregulation of the ABA biosynthetic genes SITIENS (SIT), FLACCA (FLC) and aldehyde oxidase SlAO1. SlZFP2 delays the onset of ripening through suppression of the ripening regulator COLORLESS NON-RIPENING (CNR). Using bacterial one hybrid screening and a selected amplification and binding assay we identified the (A/T)(G/C)TT repeat as the core binding sequence of SlZFP2. We further identified a large number of tomato genes containing putative SlZFP2 binding sites in their promoter regions. Chromatin immunoprecipitation and electrophoretic mobility shift assays demonstrated that SIT, FLC and SlAO1 are direct targets of SlZFP2 through binding to their promoter regions. We propose that SlZFP2 represents a novel negative regulator for fine tuning ABA biosynthesis during fruit development and provides a potentially valuable tool for dissecting the role of ABA in fruit ripening.To gain further insight on transcriptome changes regulated by SlZFP2, we sequenced a representative SlZFP2 RNAi line in LA1589 background and its nontransgenic sibling (WT) on a Miseq platform. The RNAi line 207 showed defected fruit set and ABA biosynthesis were chosen for profiling gene expression via RNA sequencing. Its nontransgenic sibling was served as controls. Three biological replicates were conducted.
Project description:Plant pathogens with a broad host range are able to infect plant lineages that diverged over 100 million years ago. They exert similar and recurring constraints on the evolution of unrelated plant populations. Plants generally respond with quantitative disease resistance (QDR), a form of immunity relying on complex genetic determinants. In most cases, the molecular determinants of QDR and how they evolve is unknown. Here we identify in Arabidopsis thaliana a gene mediating QDR against Sclerotinia sclerotiorum, agent of the white mold disease, and provide evidence of its convergent evolution in multiple plant species. Using genome wide association mapping in A. thaliana, we associated the gene encoding the POQR prolyl-oligopeptidase with QDR against S. sclerotiorum. Loss of this gene compromised QDR against S. sclerotiorum but not against a bacterial pathogen. Natural diversity analysis associated POQR sequence with QDR. Remarkably, the same amino acid changes occurred after independent duplications of POQR in ancestors of multiple plant species, including A. thaliana and tomato. Genome-scale expression analyses revealed that parallel divergence in gene expression upon S. sclerotiorum infection is a frequent pattern in genes, such as POQR, that duplicated both in A. thaliana and tomato. Our study identifies a previously uncharacterized gene mediating QDR against S. sclerotiorum. It shows that some QDR determinants are conserved in distantly related plants and have emerged through the repeated use of similar genetic polymorphisms at different evolutionary time scales. Overall design: mature leaves inoculated or not by the fungus, three independent replicates
Project description:The goal of this research was to measure the gene expression levels thoughout 10 stages of tomato fruit development. Whole buds, flowers or fruits were collected at various developmental timepoints. Overall design: Total RNA was extracted from 10 stages of flower and fruit development. A single technical and biological repeat was performed. cDNA was amplified and labelled using standard Affymetrix protocols.
Project description:NILs were created for the detailed genetic mapping of a QTL (gFW9.1) in tomato. Residual heterozygocity in recombinant inbred lines from the cross S. lycopersicum var. cerasiforme (parental accession E9) × S. pimpinellifolium line (parental accession L5) was used for the generation of a pair of NILs of which line E9 had DNA from parent E9 on a large section of chromosome 9 (5-56 Mb), whereas line L5 had parent L5 DNA. These two lines were tested as rootstocks grafted to a common scion (cv. Boludo) in multi-stress conditions - low phosphorus and drought stress compared to high phosphorus and well-watered conditions. RNA for transcriptomic analysis was prepared from root tissues. Secondary use of data: In a study aiming to identify genes that respond to multiple abiotic stresses, microarray data obtained from different plant species and under different stresses was analysed. A number of conserved stress-responsive genes were identified whose expression was differentially regulated in tomato roots in response to one or several stresses. 10 of these genes were validated as reliable biomarkers whose expression levels are related to different signalling pathways involved in adaptive stress responses. This dataset comprises part of the full stress dataset and is for plant roots harvested after growth under low phosphorus and drought conditions, compared to plant roots harvested after growth under sufficient phosphorus and well watered conditions. Overall design: The experiment was carried out wtih 4 replicates, 2 NIL lines and 2 conditions, which resulted in 16 samples. Both “E9” and “L5” rootstock lines were grafted to Boludo scions in 30 ml modules of peat-based compost, and then transplanted into 3L pots of Perlite. A combined low phosphorus and drought stress treatment was applied during plant growth, which resulted in significantly reduced plant development compared to the control treated lines. After 29 days of treatment, the root tissues were harvested and total RNA were isolated from all 16 samples. These RNAs (after RNA quality check) were used for Cy3 labelling and hybridization to 4 x180k Agilent microarrays containing probes designed for the genes of the S.lycopersicum cv. Heinz 1706 genome (each array contained ~5 probes for 34,619 transcripts). Data was normalised using the Robust Multichip Averaging algorithm.