Project description:Floral transition and flower development are regulated by numerous environmental and endogenous signals, which are integrated at a relatively small number of floral integrators, such as FLOWERING LOCUS T (FT) and SUPPRESSOR OF CONSTANS OVEREXPRESSION 1 (SOC1). Of the environmental factors, photoperiod is regarded the most important one in promoting floral transition in Arabidopsis thaliana and most labstrains will flower earlier under long day (LD) conditions than under short day (SD) conditions. Arabidopsis is therefore considered a facultative LD plant. To monitor gene expression changes during floral transition and early flower development plants were grown under SD (9 hr light, 15 hr dark) for 30 days. Plants were then shifted to LD (16 hr light, 8 hr dark) conditions to induce flowering. RNA was isolated from micro-dissected apical tissue harvested 0, 3, 5, and 7 days after the shift to LD and double-stranded cDNA was synthesized. Biotinylated cRNA probes were prepared and hybridized to the Affymetrix ATH1 array in duplicate (biological replicates). To study floral transition, we not only analyzed response of wildtype Landsberg erecta (Ler) plants, but also the effect of mutants in the flowering time genes CONSTANS (CO; co-2) and FT (ft-2). Early flower development was analyzed by comparing Col-0 wildtype plants with the meristem identity mutant lfy-12 (Col-0).
Project description:Plants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the environment. Among these processes, the floral transition is essential to ensure reproductive success and is finely regulated by several internal and external genetic networks. The photoperiodic pathway, which controls the plant response to day length, is one of the most important pathways controlling flowering. In Arabidopsis photoperiodic flowering, CONSTANS (CO) is the central gene activating the expression of the florigen FLOWERING LOCUS T (FT) in the leaves at the end of a long day. CO expression is strongly regulated by the circadian clock. However, to date, no evidence has been reported regarding a feedback loop from the photoperiod pathway back to the circadian clock. Using transcriptional networks, we have identified relevant network motifs regulating the interplay between the circadian clock and the photoperiod pathway. Gene expression, chromatin immunoprecipitation experiments and phenotypic analysis allowed us to elucidate the role of CO over the circadian clock. Plants with altered CO expression showed a different internal clock period, measured by daily rhythmic movements in the leaves. We show that CO is able to activate key genes related to the circadian clock, such as CCA1, LHY, PRR5 and GI, at the end of a long day by binding to specific sites on their promoters. Moreover, a significant number of PRR5 repressed target genes are upregulated by CO, and this could explain the phase transition promoted by CO. The CO-PRR5 complex interacts with the bZIP transcription factor HY5 and helps to localize the complex in the promoters of clock genes. Our results indicate that there may be a feedback loop in which CO communicates back to the circadian clock, feeding seasonal information to the circadian system.
Project description:Plants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the environment. Among these processes, the floral transition is essential to ensure reproductive success and is finely regulated by several internal and external genetic networks. The photoperiodic pathway, which controls the plant response to day length, is one of the most important pathways controlling flowering. In Arabidopsis photoperiodic flowering, CONSTANS (CO) is the central gene activating the expression of the florigen FLOWERING LOCUS T (FT) in the leaves at the end of a long day. CO expression is strongly regulated by the circadian clock. However, to date, no evidence has been reported regarding a feedback loop from the photoperiod pathway back to the circadian clock. Using transcriptional networks, we have identified relevant network motifs regulating the interplay between the circadian clock and the photoperiod pathway. Gene expression, chromatin immunoprecipitation experiments and phenotypic analysis allowed us to elucidate the role of CO over the circadian clock. Plants with altered CO expression showed a different internal clock period, measured by daily rhythmic movements in the leaves. We show that CO is able to activate key genes related to the circadian clock, such as CCA1, LHY, PRR5 and GI, at the end of a long day by binding to specific sites on their promoters. Moreover, a significant number of PRR5 repressed target genes are upregulated by CO, and this could explain the phase transition promoted by CO. The CO-PRR5 complex interacts with the bZIP transcription factor HY5 and helps to localize the complex in the promoters of clock genes. Our results indicate that there may be a feedback loop in which CO communicates back to the circadian clock, feeding seasonal information to the circadian system.
Project description:Transcriptional profiling of Arabidopsis thaliana 12-days old seedlings comparing Col-0 wild type with transgenic plants with altered expression of dual-targetting plastid/mitochondrial organellar RNA-polymerase RPOTmp. Transgenic plants used for experiment were: overexpressor plants obtained by transformation of Col-0 WT plants with genetic constructs created in [Tarasenko et al., 2016] contained catalytic part of RPOTmp enzyme with transit peptides of RPOTm (mitochondrial) and RPOTp (plastid) by agrobacterial transformation; plants with complementation of RPOTmp functions in mitochondria or chloroplasts obtained from transformation of GABI_286E07 rpotmp knockout-mutant plants with genetic constructs created in [Tarasenko et al., 2016]. Goal was to determine the effects of RPOTmp knockout/overexpression on global Arabidopsis thaliana gene expression.
Project description:Expression analysis was performed with two TDNA insertion mutants of taf4b i.e; taf4bprm (TDNA insertion in promoter region) and taf4bint (TDNA insertion in intronic region), Taf4b overexpression lines, taf4bprmcpr5 double mutant lines (Double mutant was generated by crossing taf4bprm with cpr5) and Col-0 in normal condition as well as with taf4bprm mutant and Col-0 infected with fungi AB (Alternaria brassicicola) and bacteria ES4 (Pseudomonas syringae pv.maculicola ES4326 ) in different perspectives. Affymatrix expression analysis was executed to provide mechanistic details of regulation of genes by Taf4b in plants.