Repression of Nitrogen Starvation Responses by Members of the Arabidopsis GARP-Type Transcription Factor NIGT1/HRS1 Subfamily.

Nitrogen (N) is often a limiting nutrient whose availability determines plant growth and productivity. Because its availability is often low and/or not uniform over time and space in nature, plants respond to variations in N availability by altering uptake and recycling mechanisms, but the molecular mechanisms underlying how these responses are regulated are poorly understood. Here, we show that a group of GARP G2-like transcription factors, NITRATE-INDUCIBLE, GARP-TYPE TRANSCRIPTIONAL REPRESSOR1/HYPERSENSITIVE TO LOW Pi-ELICITED PRIMARY ROOT SHORTENING1 proteins (NIGT1/HRS1s), are factors that bind to the promoter of the N starvation marker and repress an array of N starvation-responsive genes under conditions of high N availability.

Arabidopsis growth-regulating factor7 functions as a transcriptional repressor of abscisic acid- and osmotic stress-responsive genes, including DREB2A.

Arabidopsis thaliana DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN2A (DREB2A) functions as a transcriptional activator that increases tolerance to osmotic and heat stresses; however, its expression also leads to growth retardation and reduced reproduction. To avoid these adverse effects, the expression of DREB2A is predicted to be tightly regulated. We identified a short promoter region of DREB2A that represses its expression under nonstress conditions.

Efficient yeast one-/two-hybrid screening using a library composed only of transcription factors in Arabidopsis thaliana.

Yeast one-hybrid screening is widely used for the identification of transcription factors (TFs) that interact with specific DNA sequences. However, screening a whole cDNA library is not efficient for the identification of TFs because TF genes represent only a small percentage of clones in a cDNA library. Here, we present the development of an efficient yeast one-hybrid screening system using a prey library composed only of approximately 1,500 TF cDNAs of Arabidopsis thaliana.