Project description:Pineapple (Ananas comosus var. comosus) and ornamental bromeliads are commercially induced to flower by treatment with ethylene or its analogs. The apex is transformed from a vegetative to a floral meristem and shows morphological changes in 8 to 10 days, with flowers developing 8 to 10 weeks later. During eight sampling stages ranging from 6 hours to 8 days after treatment, 7,961 genes were found to exhibit differential expression (DEG) after the application of ethylene. In the first 3 days after treatment, there was little change in ethylene synthesis or in the early stages of the ethylene response. Subsequently, three ethylene response transcription factors (ERTF) were up-regulated and the potential gene targets were predicted to be the positive flowering regulator CONSTANS (CO), a WUSCHEL gene, two APETALA1/FRUTFULL (AP1/FUL) genes, an epidermal patterning gene and a jasmonic acid synthesis gene. We confirm that pineapple has lost the flowering repressor FLOWERING LOCUS C. At the initial stages, the SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) was not significantly involved in this transition. Another WUSCHEL gene and a PHD homeobox transcription factor, though not apparent direct targets of ERTF, were up-regulated within a day of treatment, their predicted targets being the up-regulated CO, auxin response factors, SQUAMOSA, and histone H3 genes with suppression of abscisic acid response genes. The FLOWERING LOCUS T (FT), TERMINAL FLOWER (TFL), AGAMOUS-like APETELAR (AP2) and SEPETALA (SEP) increased rapidly within 2 to 3 days after ethylene treatment. Two FT genes were up-regulated in the apex and not the leaf bases after treatment, suggesting that transport did not occur. These results indicated that the ethylene response in pineapple and possibly most bromeliads acts directly to promote the vegetative to flower transition via APETALA1/FRUITFULL (AP1/FUL) and its interaction with SPL, FT, TFL, SEP and AP2.
Project description:Pineapple is a non climacteric fruit. This study investigates changes in gene expression between the mature green fruit and mature yellow fruit ripening stages
Project description:DNA methylation is critical for development and is strongly associated with gene regulation. Variation in the DNA methylome between closely related species may reveal unique functional adaptation. We have implemented a novel inter-primate DNA methylation genome-wide analysis between human, chimpanzee and rhesus macaque to identify human species-specific Differentially Methylated Regions (human s-DMRs) in orthologous loci. We analysed the peripheral blood cell DNA methylomes of these primates and identified 22,758 hypomethylated and 15,858 hypermethylated human s-DMRs. These s-DMRs are globally enriched within weak promoter, enhancer and transcribed regions via comparison with ChromHMM segmentation. Human s-DMRs, (both hypo- and hypermethylated) are found to be more prevalent in CpG Island shores than within the islands themselves (?2 P = 1.80 x 10-32). Examining human-specific Transcription Factor Binding Site motif change within CpG islands, we show gain and loss, in hypomethylated and hypermethylated s-DMRs, respectively, of CTCF motifs. Epigenetically the most divergent human-specific locus was the immunological Leukotriene B4 receptor (LTB4R, aka BLT1 receptor), due to collocating hypomethylated s-DMRs within the promoter CpG island and shore, as well as inverse increased gene body methylation. This gene is vital in host immune responses and associated with the pathogenesis of a wide range of human inflammatory diseases. This finding was supported by additional neutrophil-only DNA methylome and lymphoblastoid H3K4me3 chromatin comparative data. Functional investigation of the consequences of these epigenetic differences identified this receptor to have increased expression, and have a higher response to the LTB4 ligand in human versus rhesus macaque peripheral blood mononuclear cells. This result further emphasises the exclusive nature of the human immunological system, its divergent adaptation even from closely related primates, and the power of comparative epigenomics to identify and understand human uniqueness. DNA methylome analysis of pooled Human, Chimpanzee and Macaque
Project description:Purpose: We characterized genome-wide DNA methylation profiles (methylome) in purified peripheral blood monocytes (PBMs) from 18 healthy postmenopausal Caucasian females aged 50-56 years. Methods: DNA methylome of Human Peripheral Blood Monocytes were generated by methylated DNA immunoprecipitation combined with high-throughput sequencing (MeDIP-seq), using Illumina GAIIx. The sequence reads that passed quality filters were analyzed using MEDIPS package. Targeted methylation validation analysis was performed by using MassARRAY EpiTYPER assays. Genome-wide gene expression profiles have been obtained for 7 of the 18 subjects by using Affymetrix 1.0 Human Exon ST arrays following the manufacturer's recommended protocols. Results: Using MeDIP-seq,a total of approximately 283 million reads were uniquely aligned to human genome (Build NCBI37, HG19), resulting in average ~16 million uniquely aligned high quality reads per sample. Distinct patterns were revealed at different genomic features. For instance, promoters were commonly (~58%) found to be unmethylated; whereas protein coding regions were largely (~84%) methylated. We found that approximately 24% CpG islands (CGIs) were highly methylated in PBMs. Further characterization of CGIs with respect to their relative locations to RefSeq genes revealed that the highly methylated CGIs were largely enriched (~89%) in CGIs located in gene bodies and intergenic regions. By integration of the methylome data with genome-wide PBM gene expression data, we found negative correlation between promoter methylation levels and gene transcription levels when comparing groups of genes with different expression levels, and this relationship was consistently observed across promoters with high to low CpG densities. Furthermore, we observed a modest but significant excess (permutation p<0.0001) of genes showing negative correlation between inter-individual promoter methylation and transcription levels, particularly for genes associated with CpG-rich promoters. Across the 18 individual PBM methylomes, we also identified genomic regions that were constitutively highly methylated in PBMs as well as regions showing large inter-individual variability. Conclusions: This study represents a comprehensive analysis of the PBM methylome and our data provides a valuable resource for future epigenomic and multi-omic studies exploring biological and disease-related regulatory mechanisms in PBMs. DNA methylome of human peripheral blood monocytes were generated by MeDIP-seq, using Illumina GAIIx.
Project description:Peel color is a key factor that affects the fruit’s aesthetic and economic values. In Red Sugar pineapple, the peels’ red color reduces during maturation. Limited knowledge is available on the regulation of pineapple peel discoloration, which makes it important to study the molecular mechanisms associated with this important trait. Here, we report that a decrease in anthocyanin biosynthesis is predominantly associated with the pineapple peel color change during maturation. Particularly the exclusive accumulation of cyanidin in 60 days after flowering (DAF) as compared to 120 DAF gives the fruit peel its distinct reddish color. Our findings suggest that the changes in the expression of key structural genes (early and late biosynthetic genes) of the anthocyanin (cyanidin) biosynthesis pathway are responsible for peel discoloration. Based on a gene co-expression analysis and a transient expression, we identified two transcription factors i.e., AcHOX21 and AcMYB12, and showed that their downregulation leads to the reduced anthocyanin accumulation with fruit maturation.