Project description:When grown under phosphate (Pi) deficiency, plants adjust their developmental program and metabolic activity to cope with this nutritional stress. For Arabidopsis, the developmental responses include inhibition of primary root growth and enhanced formation of lateral roots and root hairs. Pi deficiency also inhibits photosynthesis by suppressing the expression of photosynthetic genes. Interestingly, early studies showed that photosynthetic gene expression was also suppressed in roots, a non-photosynthetic tissue. The biological relevance of this phenomenon, however, is not known. In this work, we characterized an Arabidopsis mutant, hps7, which is hypersensitive to Pi deficiency; the hypersensitivity includes an increased inhibition of root growth. HPS7 encodes a tyrosylprotein sulfotransferase (TPST). Accumulation of TPST proteins, but not mRNA, is induced by Pi deficiency. Comparative RNA-Seq analyses indicated that expression of many photosynthetic genes was activated in the roots of hps7. Under Pi deficiency, the expression of the photosynthetic genes in hps7 is further increased, which leads to the enhanced accumulation of chlorophyll, starch, and reactive oxygen species. The increased inhibition of root growth in hps7 under Pi deficiency was completely reversed by growing plants in the dark. Based on these results, we propose that suppression of photosynthetic gene expression in roots is required for sustained root growth under Pi deficiency.
Project description:This SuperSeries is composed of the following subset Series:; GSE10496: Expression analysis of the effect of protoplasting and FACS sorting in roots exposed to iron deficiency (-Fe); GSE10497: Expression analysis of root developmental zones after iron deficiency (-Fe) treatment; GSE10501: Expression analysis of root cell-types after iron deficiency (-Fe) treatment; GSE10502: Time course expression analysis of the iron deficiency (-Fe) response in Arabidopsis roots Experiment Overall Design: Refer to individual Series
Project description:To optimize access to nitrogen under limiting conditions, root systems must continuously sense and respond to local or temporal fluctuations in nitrogen availability. In Arabidopsis thaliana and several other species, external N levels that induce only mild deficiency stimulate the emergence of lateral roots and especially the elongation of primary and lateral roots. However, the identity of the genes involved in this coordination remains still largely elusive. In order to identify novel genes and mechanisms underlying nitrogen-dependent root morphological changes, we investigated time-dependent changes in the root transcriptome of Arabidopsis thaliana plants grown under sufficient nitrogen or under conditions that induced mild nitrogen deficiency.
Project description:⢠Selected soil-borne rhizobacteria can trigger an induced systemic resistance (ISR) that is effective against a broad spectrum of pathogens. In Arabidopsis thaliana, the root-specific transcription factor MYB72 is required for the onset of ISR, but is also associated with plant survival under conditions of iron deficiency. Here we investigated the role of MYB72 in both processes. ⢠To identify MYB72 target genes, we analyzed the root transcriptomes of wild-type Col-0, mutant myb72, and complemented 35S:FLAG-MYB72/myb72 plants in response to ISR-inducing Pseudomonas fluorescens WCS417. ⢠Five WCS417-inducible genes were misregulated in myb72 and complemented in 35S:FLAG-MYB72/myb72. Amongst these, we uncovered β-glucosidase BGLU42 as a novel component of the ISR signaling pathway. Overexpression of BGLU42 resulted in constitutive disease resistance, whereas bglu42 was defective in ISR. Furthermore, we found 195 genes to be constitutively upregulated in MYB72-overexpressing roots in the absence of WCS417. Many of these encode enzymes involved in the production of iron-mobilizing phenolic metabolites under conditions of iron deficiency. We provide evidence that BGLU42 is required for their release into the rhizosphere. ⢠Together, this work highlights a thus far unidentified link between the ability of beneficial rhizobacteria to stimulate systemic immunity and mechanisms induced by iron deficiency in host plants. Total 18 samples of RNA extracted from Arabidopsis roots: Three genotypes: 1) Wild-type Arabidopsis thaliana accession Col-0, 2) mutant myb72-2 (Col-0 background), 3) Transgenic 35S:FLAG-MYB72 (oxMYB72) in the myb72-2 background; Two treatments: 1) non-treated control, 2) Roots colonized by beneficial Pseudomonas fluorescens WCS417 rhizobacteria; Replicates: three biological replicates per genotype/treatment combination
Project description:MYB10 and MYB72 are two transcription factors expressed in Arabidopsis roots under iron deficiency. To understand the contribution of these factors, we analyzed gene expression in roots of wild-type (Col) and mutant (myb10myb72 double knockout) seedlings exposed to iron deficiency for 72 hours.