Project description:We used RNA-seq to profile gene expression changes during flg22 activated pattern-triggered immunity in multiple Brassicaceae including Capsella rubella, Cardamine hirsuta and Eutrema salsugineum as well as in multiple Arabidopsis thaliana accessions. This allows comparative transcriptomics within and across species to investigate the evolution of stress-responsive transcrption changes in these species.
Project description:Genome-wide landscapes of transcription factor (TF) binding sites (BSs) diverge during evolution, conferring species-specific transcriptional patterns. The rate of divergence varies in different metazoan lineages but has not been widely studied in plants. We identified the BSs and assessed the effects on transcription of FLOWERING LOCUS C (FLC) and PERPETUAL FLOWERING 1 (PEP1), two orthologous MADS-box TFs that repress flowering and confer vernalization requirement in the Brassicaceae species Arabidopsis thaliana and Arabis alpina, respectively. We found the BSs that were conserved in both species, and that these contained a CArG-box that is recognised by MADS-box TFs. The CArG-box consensus at conserved BSs was extended compared to the core motif. By contrast, species-specific BSs usually lacked the CArG-box in the other species. Flowering-time genes were highly overrepresented among conserved targets and their CArG-boxes were widely conserved among Brassicaceae species. Cold-regulated genes (COR) were also overrepresented among targets, but the cognate BSs and the identity of the regulated genes were different in each species. In cold, COR gene transcript levels were increased in flc and pep1-1 mutants compared to wild-type and this correlated with reduced growth in pep1-1. Therefore FLC orthologs regulate a set of conserved target genes mainly involved in reproductive development and were later independently recruited to modulate stress responses in different Brassicaceae lineages. Analysis of TF BSs in these lineages thus distinguishes widely conserved targets representing the core function of the TF from those that were recruited later in evolution.
Project description:Genome-wide landscapes of transcription factor (TF) binding sites (BSs) diverge during evolution, conferring species-specific transcriptional patterns. The rate of divergence varies in different metazoan lineages but has not been widely studied in plants. We identified the BSs and assessed the effects on transcription of FLOWERING LOCUS C (FLC) and PERPETUAL FLOWERING 1 (PEP1), two orthologous MADS-box TFs that repress flowering and confer vernalization requirement in the Brassicaceae species Arabidopsis thaliana and Arabis alpina, respectively. We found that only 17% of their BSs were conserved in both species and that these contained a CArG-box that is recognised by MADS-box TFs. The CArG-box consensus at conserved BSs was extended compared to the core motif. By contrast, species-specific BSs usually lacked the CArG-box in the other species. Flowering-time genes were highly overrepresented among conserved targets and their CArG-boxes were widely conserved among Brassicaceae species. Cold-regulated genes (COR) were also overrepresented among targets, but the cognate BSs and the identity of the regulated genes were different in each species. In cold, COR gene transcript levels were increased in flc and pep1-1 mutants compared to wild-type and this correlated with reduced growth in pep1-1. Therefore FLC orthologs regulate a set of conserved target genes mainly involved in reproductive development and were later independently recruited to modulate stress responses in different Brassicaceae lineages. Analysis of TF BSs in these lineages thus distinguishes widely conserved targets representing the core function of the TF from those that were recruited later in evolution.
Project description:Petal is not only the target of selection by horticulturalists to enhance the ornamental value of plants but also emerged as a unique model system for plant organogenesis studies. It is known that three major groups of pigments, betalains, carotenoids and anthocyanins, are responsible for the attractive natural display of flower colors. While carotenoids and betalains generally yield yellow or red colors, anthocyanins confer a diverse range of color from orange to red to violet and blue. In this study, we collected 11 species (Erysimum cheiri, Malcolmia maritime, Brassica oleracea, Raphanus sativus, Orychophragmus violaceus, Eruca sativa, Orychophragmus violaceus, Iberis amara, Aubrieta x cultorum, Lobularia maritime, Matthiola incana) belong to different tribe in Brassicaceae family with varied flower color and performed petal transcriptome analysis. de novo transcriptome assembly showed that average length of the contigs varied from 631bp in O. violaceus to 1212bp in Matthiola incana which indicated that the complexity of the genomes are different much. Protein homology between these species and those sequenced species in Brassicaceae family are consistent with the known phylogenetic relationships. However, O. violaceus has closer relationships with Sisymbrium irio than expected Brassica species. Clustering analysis of genes in anthocyanin and carotenoids synthesis pathway indicated that while silence or low expression of CCD4 (Carotenoid Cleavage Dioxygenase 4) leading to the yellow color formation in different species, purple or red color variation might result from different genes expression variation. These results not only provide transcriptome data for petal development study but also provide useful information for Brassica flower improvement for ornamental purpose.
Project description:Expression profiling of A. thaliana, A. stelleri, R. islandica, and T. salsuginea under the low-oxygen treatment(0.1% O2/99.9% N2, various time points at 0, 1, 3, 8, 24, 72h) Comparative analysis of transcriptional responses to low-oxygen stress with Arabidopsis and its related species to gain comprehensive insights into low-oxygen responses of the species.