title: Genome-wide data (ChIP-seq) enabled identification of cell wall-related and aquaporin genes as targets of tomato ASR1, a drought stress-responsive transcription factor.
abstract: BACKGROUND
  Identifying the target genes of transcription factors is important for unraveling regulatory networks in all types of organisms. Our interest was precisely to uncover the spectrum of loci regulated by a widespread plant transcription factor involved in physiological adaptation to drought, a type of stress that plants have encountered since the colonization of land habitats 400 MYA. The regulator under study, named ASR1, is exclusive to the plant kingdom (albeit absent in Arabidopsis) and known to alleviate the stress caused by restricted water availability. As its target genes are still unknown despite the original cloning of Asr1 cDNA 20 years ago, we examined the tomato genome for specific loci interacting in vivo with this conspicuous protein.
  
  
  RESULTS
  We performed ChIP followed by high throughput DNA sequencing (ChIP-seq) on leaves from stressed tomato plants, using a high-quality anti-ASR1 antibody. In this way, we unraveled a novel repertoire of target genes, some of which are clearly involved in the response to drought stress. Many of the ASR1-enriched genomic loci we found encode enzymes involved in cell wall synthesis and remodeling as well as channels implicated in water and solute flux, such as aquaporins. In addition, we were able to determine a robust consensus ASR1-binding DNA motif.
  
  
  CONCLUSIONS
  The finding of cell wall synthesis and aquaporin genes as targets of ASR1 is consistent with their suggested role in the physiological adaptation of plants to water loss. The results gain insight into the environmental stress-sensing pathways leading to plant tolerance of drought.
authors.forename: Martiniano M
authors.initials: MM
authors.lastname: Ricardi
authors.forename: Rodrigo M
authors.initials: RM
authors.lastname: González
authors.forename: Silin
authors.initials: S
authors.lastname: Zhong
authors.forename: Pía G
authors.initials: PG
authors.lastname: Domínguez
authors.forename: Tomas
authors.initials: T
authors.lastname: Duffy
authors.forename: Pablo G
authors.initials: PG
authors.lastname: Turjanski
authors.forename: Juan D
authors.initials: JD
authors.lastname: Salgado Salter
authors.forename: Karina
authors.initials: K
authors.lastname: Alleva
authors.forename: Fernando
authors.initials: F
authors.lastname: Carrari
authors.forename: James J
authors.initials: JJ
authors.lastname: Giovannoni
authors.forename: José M
authors.initials: JM
authors.lastname: Estévez
authors.affiliation: Instituto de Fisiología, Biología Molecular y Neurociencias (IFIByNE)-CONICET, Buenos Aires, Argentina. norbius@fbmc.fcen.uba.ar.
authors.forename: Norberto D
authors.initials: ND
authors.lastname: Iusem
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D014157:Transcription Factors