Project description:Plants reorganize their root architecture to avoid growth into unfavorable regions of the rhizosphere. In a screen based on chimeric repressor gene-silencing technology, we identified the Arabidopsis thaliana GeBP-LIKE 4 (GPL4) transcription factor as an inhibitor of root growth that is induced rapidly in root tips in response to cadmium (Cd). We tested the hypothesis that GPL4 functions in the root avoidance of Cd by analyzing root proliferation in split medium, in which only half of the medium contained toxic concentrations of Cd. The wild-type (WT) plants exhibited root avoidance by inhibiting root growth in the Cd side but increasing root biomass in the control side. By contrast, GPL4-suppression lines exhibited nearly comparable root growth in the Cd and control sides and accumulated more Cd in the shoots than did the WT. GPL4 suppression also altered the root avoidance of toxic concentrations of other essential metals, modulated the expression of many genes related to oxidative stress, and consistently decreased reactive oxygen species concentrations. We suggest that GPL4 inhibits the growth of roots exposed to toxic metals by modulating reactive oxygen species concentrations, thereby allowing roots to colonize noncontaminated regions of the rhizosphere.thereby re-allocating root biomass toward non-contaminated rhizosphere areas and minimizing root exposure to toxic metals.
Project description:Shade avoidance syndrome (SAS) is a strategy of major adaptive significance that includes the elongation of vegetative structures and leaf hyponasty. Major transcriptional rearrangements underlie for the reallocation of resources to elongate vegetative structures and redefine the plant architecture under shade to compete for photosynthesis light. BBX28 is a transcription factor involved in seedling de-etiolation and flowering in Arabidopsis thaliana, but its function in the SAS is completely unknown. Here we studied the function of BBX28 in the regulation of gene expression under simulated shade conditions.
Project description:We characterised mutants in the GRAS family transcription factor AtSCL26 in Arabidopsis thaliana using a combination of gene functional analysis, hormone treatments and expression profiling at the cell type level. This has enabled us to implicate AtSCL26 in the cell-specific control of nitrogen-giberellic acid response cross-talk to control root architecture.
Project description:Sequence-specific transcription factor WRKY75 is highly responsive to reactive oxygen species on transcriptional level in the rosettes of Arabidopsis thaliana. In addition, it acts in developmental responses, acquisition of nutrients, and in stress responses. In the root, WRKY75 is a repressor of root hair formation, it regulates the phosphate starvation response, and the response to certain pathogens. In order to find the target genes of WRKY75, the effects of estradiol-inducible overexpression of WRKY75 on transcriptome was studied using RNA-seq.
Project description:Oxygen is a key signalling component of plant biology and, whilst an oxygen-sensing mechanism was previously described in Arabidopsis thaliana. However, key features of the associated PCO N-degron pathway and Group VII ETHYLENE RESPONSE FACTOR (ERFVII) transcription factor substrates remain unknown. We demonstrate that ERFVIIs show non-autonomous activation of root hypoxia tolerance, and are essential for root development and survival under oxygen limiting conditions in the soil. We determine the combined effects of ERFVIIs in controlling genome expression and define genetic and environmental components required for proteasome-dependent oxygen-regulated stability of ERFVIIs through the PCO N-degron pathway. Using a plant extract, unexpected amino-terminal cysteine oxidation to sulphonic acid oxidation level of ERFVIIs was defined, suggesting a requirement for additional enzymatic activity within the pathway. Our results provide a holistic understanding of the properties, functions and readouts of this oxygen-sensing mechanism defined through its role in modulating ERFVII stability.
Project description:Nano-aluminium oxide (nAl2O3) is one of the most widely used nanomaterials, but the molecular toxic mechanism of nAl2O3 on plants is still not clarified completely. In this study, we compared the toxic effects of nAl2O3 and Al3+ ion at the physiological and molecular levels. The shoot weight and root weight of Arabidopsis thaliana were decrease to 57.01% and 45.15% after the Al3+ ion exposure , while nAl2O3 increased the root weight by 48.07% and length by 38.53% at the selected concentration (98 mmol/L) for 10 d exposure. Physiological research showed that the photosystem (chlorophyll fluorescence parameters down-regulated) and antioxidant system (MDA and H2O2 content up-regulated) in A. thaliana were severely injured by the Al3+ ion. Data from transcriptome analysis clarified how nAl2O3 and Al3+ ion selectively affected root development and growth. nAl2O3 stimulated root growth directly (e.g., up-regulation of the root hair-specific gene family and root development genes, POLARIS protein), or indirectly (e.g., up-regulation of N and P absorption-related genes). Conversely, Al3+ ion disturbed ion homeostasis (up-regulated Al and Cu content) and caused severe oxidative stress, thus activating the salicylic acid (SA) signaling pathway and up-regulating nitric oxide (NO)-related genes, inducing the plant defense response. However, the overproduced SA and NO (up-regulated 2.60-fold) led to the inhibition of CAT activity (down-regulation of CAT1 and CAT2 genes) and increased the H2O2 level (up-regulated 2.84-fold). Subsequently, root development-related genes (e.g., auxin induced in root cultures 1) were down-regulated. This work gives us new insight into understanding the different molecular mechanisms of the plant response to nAl2O3 and Al3+ stresses.