Project description:MicroRNAs (miRNAs) are important post-transcriptional regulators of plant development. In soybean (Glycine max), an important edible oil crop, valuable lipids are synthesized and stored in the cotyledons during embryogenesis .This storage lipids are used as energy source of the emerging seeds, during the germination procces. Until now, there are no microRNAs related to lipid metabolism in soybean or any other plant. This work aims to describe the miRNAome of germinating seeds of B. napus by identifying plant-conserved and novel miRNAs and comparing miRNA abundance in mature versus germinating seeds. A total of 183 familes were detected through a computational analysis of a large number of reads obtained from deep sequencing from two small RNA libraries of (i) pooled germintaing seeds stages and (ii) mature soybean seeds. We have found 39 new mirna precursors which produce 41 new mature forms. The present work also have identified isomiRNAs and mirnas offset (moRNAs). This work presents a comprehensive study of the miRNA transcriptome of soybean germinating seeds and will provide a basis for future research on more targeted studies of individual miRNAs and their functions in lipid consumption in development soybean seeds.
Project description:Heat stressed Arabidopsis plants release heterochromatin-associated transposable element (TE) silencing, which however is not accompanied by major reductions of epigenetic repressive modifications. In this study, we explored the functional role of histone H1 in repressing heterochromatic TEs in response to heat stress. Loss of H1 caused activation of pericentromeric GYPSY elements upon heat treatment, despite that these elements remained highly methylated. In contrast, non-pericentromeric COPIA elements became activated concomitantly with loss of DNA methylation. The same COPIA elements became activated in heat-treated chromomethylase2 (cmt2) mutants, indicating that H1 represses COPIA elements through maintaining DNA methylation under heat. We discovered that H1 is required for TE repression in response to heat stress, but its functional role differs depending on TE location. Strikingly, H1 deficient plants treated with the DNA methyltransferase inhibitor zebularine were highly tolerant to heat stress, suggesting that both, H1 and DNA methylation redundantly suppress the plant response to heat stress.
Project description:Understanding the mechanisms of transcriptional regulation for genes involved with FA biosynthesis and TAG accumulation in seeds can represent an important step in the development of crops with increased oil content. Among well studied transcription factors (TFs), WRINKLED1 (WRI1), a member of the APETALA2 (AP2) family of TFs, has been characterized as a central regulator of FA biosynthesis in seeds of many plant species. Despite its importance for the process, the detailed mechanisms of WRI1 function in regulating FA biosynthesis in seeds is still not well understood. This study aimed to characterize the gene networks controled by WRI1 during soybean embryo development and its function as central regulator of FA biosynthesis and TAG accumulation in seeds. In this part of the study, we identified genes regulated by the soybean WRI1s (GmWRI1s) by overexpressing GmWRI1-A (Glyma.08G227700) in Arabidopsis leaf mesophyll protoplasts, and identifying the mRNAs that are induced 16h after transfection.
Project description:We describe an application of deep sequencing and de novo assembly of short RNA reads to investigate small interfering (si)RNAs mediated immunity in leaf samples from eight tree taxa naturally occurring in Wytham Woods, Oxfordshire, UK. BLAST search for homologues of contigs in the GenBank identified siRNA populations against a number of RNA viruses and a Ty1-copia retrotransposons in these tree species.
Project description:MicroRNAs (miRNAs) are important post-transcriptional regulators of plant development. In soybean (Glycine max), an important edible oil crop, valuable lipids are synthesized and stored in the cotyledons during embryogenesis .This storage lipids are used as energy source of the emerging seeds, during the germination procces. Until now, there are no microRNAs related to lipid metabolism in soybean or any other plant. This work aims to describe the miRNAome of germinating seeds of B. napus by identifying plant-conserved and novel miRNAs and comparing miRNA abundance in mature versus germinating seeds. A total of 183 familes were detected through a computational analysis of a large number of reads obtained from deep sequencing from two small RNA libraries of (i) pooled germintaing seeds stages and (ii) mature soybean seeds. We have found 39 new mirna precursors which produce 41 new mature forms. The present work also have identified isomiRNAs and mirnas offset (moRNAs). This work presents a comprehensive study of the miRNA transcriptome of soybean germinating seeds and will provide a basis for future research on more targeted studies of individual miRNAs and their functions in lipid consumption in development soybean seeds. MicroRNA profiles in 2 different seed libraries (mature seeds and a pool of germinating seed stages) of Glycine max by deep sequencing (Illumina GAII).
Project description:MicroRNAs (miRNAs) are important post-transcriptional regulators of plant development and seed formation. In Brassica napus, an important edible oil crop, valuable lipids are synthesized and stored in specific seed tissues during embryogenesis. The miRNA transcriptome of B. napus is currently poorly characterized, especially at different seed developmental stages. This work aims to describe the miRNAome of developing seeds of B. napus by identifying plant-conserved and novel miRNAs and comparing miRNA abundance in mature versus developing seeds. A total of 62 miRNA families were detected through a computational analysis of a large number of reads obtained from deep sequencing two small RNA and two RNA-seq libraries of (i) pooled immature developing stages and (ii) mature B. napus seeds. Among these miRNA families, 17 families are currently known to exist in B. napus; additionally, 32 families not reported in B. napus but conserved in other plant species were identified by alignment with known plant mature miRNAs. The contigs from the assembled mRNA-seq data allowed for a search for putative new precursors and led to the identification of 13 novel miRNA families. Differential expression between the libraries was determined through a statistical analysis of normalized miRNA reads and revealed several miRNAs and isomiRNAs that were more abundant during the developing stages. The predicted miRNA target genes encode a broad range of proteins related to seed development and energy storage. This work presents a comprehensive study of the miRNA transcriptome of B. napus seeds and will provide a basis for future research on more targeted studies of individual miRNAs and their functions in embryogenesis, seed maturation and lipid accumulation in B. napus.
Project description:In organisms ranging from vertebrates to plants, major components of centromeres are rapidly-evolving repeat sequences, such as tandem repeats (TRs) and transposable elements (TEs). These repeats harbor centromere-specific histone H3 (CENH3), which also evolves rapidly. Complete centromere structures recently determined in human and Arabidopsis suggest frequent integration and purging of retrotransposons within the TR regions of centromeres. Despite the high impact of “centrophilic” retrotransposons on the paradox of rapid centromere evolution, the mechanisms involved in centromere targeting remain poorly understood in any organism. Here we show that both Ty3 and Ty1/Copia LTR elements rapidly turnover within the centromeric TRs of Arabidopsis species. We demonstrate that the Ty1/Copia element Tal1 (Transposon of Arabidopsis lyrata 1) integrates de novo into regions occupied by CENH3 in A. thaliana, and that ectopic expansion of the CENH3 region results in spread of Tal1 integration regions. The integration spectra of chimeric TEs revealed the key structural variations responsible for the contrasting chromatin targeting specificities to centromeres versus gene-rich regions, which have recurrently converted during the evolution of these TEs. Our findings reveal the impact of centromeric chromatin on TE-mediated rapid centromere evolution, with relevance across eukaryotic genomes.
Project description:Retroelements, the prevalent class of plant transposons, have major impacts on host genome integrity and evolution. They produce multiple proteins from highly compact genomes and, similarly to viruses, must have evolved original strategies to optimize gene expression, although this aspect has been seldom investigated thus far. Here, we have established a high-resolution transcriptome/translatome map for the near-entirety of Arabidopsis thaliana transposons, using two distinct DNA methylation mutants in which transposon expression is broadly de-repressed. The value of this map to study potentially intact and transcriptionally active transposons in Arabidopsis thaliana is illustrated by our comprehensive analysis of the co-transcriptional and translational features of Ty1/Copia elements, a family of young and active retroelements in plant genomes, and how such features impact their biology. Genome-wide transcript profiling revealed a unique and widely conserved alternative splicing event coupled to premature termination that allows for the synthesis of a short subgenomic RNA solely dedicated to production of the Gag structural protein and preferentially associates with polysomes for efficient translation. Mutations engineered in a transgenic version of the Arabidopsis EVD Ty1/Copia element further show how alternative splicing is crucial for the appropriate coordination of full length and subgenomic RNA transcription. We propose that this hitherto undescribed genome expression strategy, conserved amongst plant Ty1/Copia elements, enables an excess of structural versus catalytic components, mandatory for mobilization.