Project description:Plant development is characterised by the capacity to reprogram differentiated cells to initiate asexual reproduction and to produce new organs such as lateral roots. To test whether HIRA could be involved in aspects of developmental reprogramming we studied the effect of HIRA during de-differentiation Arabidopsis root tissue was digested with enzyme to generate protoplast. This process would induce plant cell dedifferentiation. Experiments were performed in WT and hira background to understand how hira affect plant dedifferentiation process.
Project description:Histone chaperones and chromatin remodelers control nucleosome dynamics, essential for transcription, replication, and DNA repair. The histone chaperone Anti-Silencing Factor 1 (ASF1) plays a central role in facilitating CAF-1-mediated replication-dependent H3.1 deposition and HIRA-mediated replication-independent H3.3 deposition in yeast and metazoans. Whether ASF1 function is evolutionarily conserved in plants is unknown. Here, we show that Arabidopsis ASF1 proteins display an exclusive preference for the H3.3-depositing HIRA complex. Simultaneous mutation of both Arabidopsis ASF1 genes caused a decrease in chromatin density and ectopic H3.1 occupancy at loci typically enriched with H3.3. Genetic, transcriptomic, and proteomic data indicate that ASF1 proteins strongly prefer the HIRA complex over CAF-1. asf1 mutants also displayed an increase in spurious Pol II transcriptional initiation, and showed defects in the maintenance of gene body CG DNA methylation and in the distribution of histone modifications. Furthermore, ectopic targeting of ASF1 caused excessive histone deposition, less accessible chromatin, and gene silencing. These findings reveal the importance of ASF1-mediated H3.3-H4 deposition via the HIRA pathway for proper epigenetic regulation of the genome.
Project description:DNA methylation is an important epigenetic modification involved in many biological processes, and active DNA demethylation plays critical roles in regulating expression of genes and anti-silencing of transgenes. In this study, we isolated mutations in one arabidopsis gene, ROS5, which causes the silencing of transgenic 35S-NPTII because of DNA hypermethylation, but no effect on transgenic RD29A-LUC. ROS5 encodes an atypical small heat shock protein. ROS5 can physically interact with IDM1 and is required for preventing DNA hypermethylation of some endogenous genes that are also regualated by IDM1 and ROS1. We propose that ROS5 may regulate active DNA demethylation by interacting with IDM1, thereby creating a friendly chromatin environment that facilitates the binding of ROS1 to erase DNA methylation.
Project description:Plant volatiles can mediate plant-plant communication in the sense that plants attacked by herbivores can signal their unattacked neighbors of danger by emitting HIPVs. We call this the priming effect. Since the plant defense response is a systematic process involving numerous pathways and genes,to characterize the priming process, a time course study using a genome-wide microarray may provide more accurate information about the priming process. Furthermore, to what extent do the priming process and direct defense share similar gene expression profiles or pathways are also not clear. We used microarray to detect the priming effect of plant volatiles to healthy Arabidopsis thaliana, and the effect of direct leafminer feeding to Arabidopsis thalianas.
Project description:MicroRNAs (miRNAs) are 21-24 nucleotide (nt) small non-coding RNAs that regulate a wide variety of biological processes at the posttranscriptional level. MiRNA expression often exhibits spatial and temporal specificity. However, genome-wide miRNA expression patterns in different Arabidopsis organs during plant development have not yet been fully investigated. In this study, we sequenced 59 small RNA libraries generated from different tissue types at different developmental stages of Arabidopsis. We then re-annotated Arabidopsis miRNAs based on the most recent criteria. Global analysis of miRNA expression patterns showed that most miRNAs are ubiquitously expressed in different organs or tissues. But a small set of miRNAs, either previously annotated or newly identified, show highly specific expression patterns. In addition, the expression of some miRNA members belonging to the same family is strictly regulated spatially and temporally. Unexpectedly, we found that quite a few miRNAs are produced from different arms of their hairpin precursors at different developmental stages, suggesting that arm switching could be a general and important mechanism in developmental regulation.
Project description:For shade-intolerant plants, changes in light quality indicative of competition from neighboring plants trigger shade avoidance syndrome (SAS). PYHTOCHROME-INTERACTING FACTOR 7 is the major transcriptional regulator of SAS in Arabidopsis. However, the epigenetic reprogramming under shade is poorly understood. To identify the histone chaperone ASF1 and HIRA function during SAS, we performed transcriptome deep sequencing (RNA-seq) to search for differentially expressed genes (DEGs) by comparing transcript levels between Col-0 and pif7-1, asf1ab, or hira-1 seedlings during white light and shade conditions. Our data shown that histone chaperone ASF1, through interacting with PIF7 and helping of HIRA, positively regulates shade-induced genes expression.