Project description:Effect of the cytokinin BA on wt and arr1,10,12 mutant seedlings The type B Arabidopsis Response Regulators (ARRs) of Arabidopsis thaliana are transcription factors that act as positive regulators in the two-component cytokinin signaling pathway. We employed a mutant-based approach to perform a detailed characterization of the roles of ARR1, ARR10, and ARR12 in plant growth and development. The most pronounced phenotype was found in the arr1-3 arr10-5 arr12-1 triple loss-of-function mutant, which showed almost complete insensitivity to high levels of exogenously applied cytokinins. The triple mutant exhibited reduced stature due to decreased cell division in the shoot, enhanced seed size, increased sensitivity to light, altered chlorophyll and anthocyanin concentrations, and an aborted primary root with protoxylem but no metaxylem. Microarray analysis revealed that expression of the majority of cytokinin-regulated genes requires the function of ARR1, ARR10, and ARR12. Characterization of double mutants revealed differing contributions of the type B ARRs to mutant phenotypes. Our results support a model in which cytokinin regulates a wide array of downstream responses through the action of a multistep phosphorelay that culminates in transcriptional regulation by ARR1, ARR10, and ARR12. This data was originally made available through ArrayExpress under the accession number E-MEXP-1573.
Project description:Protein abundance and phosphoproteome profiling of wild-type (WT) as well as quadruple mutant plants deficient in G alpha, G beta, and two out of the three G gamma subunits, in Arabidopsis. WT plants are Col-0 and the quadruple mutant consists ofgpa1-4, agb1-2, agg1-1, and agg2-1 mutants.
Project description:We performed a microarray experiment to assess the global changes in transcription occurring in leaves and roots of the vitamin B6 deficient pdx1.3 knockout mutant in comparison to WT. Vitamin B6 (pyridoxal 5′-phosphate) is an essential cofactor of many metabolic enzymes. Plants biosynthesize the vitamin de novo employing two enzymes, pyridoxine synthase1 (PDX1) and PDX2. In Arabidopsis (Arabidopsis thaliana), there are two catalytically active paralogs of PDX1 (PDX1.1 and PDX1.3) producing the vitamin at comparable rates. Since single mutants are viable but the pdx1.1 pdx1.3 double mutant is lethal, the corresponding enzymes seem redundant. However, the single mutants exhibit substantial phenotypic differences, particularly at the level of root development, with pdx1.3 being more impaired than pdx1.1. Here, we investigate the impact of possible global changes in gene expression in the pdx1.3 mutant compared to WT on the phenotype.