title: AtbHLH68 transcription factor contributes to the regulation of ABA homeostasis and drought stress tolerance in Arabidopsis thaliana.
abstract: Basic helix-loop-helix (bHLH) transcription factors are involved in a wide range of developmental processes and in response to biotic and abiotic stresses. They represent one of the biggest families of transcription factors but only few of them have been functionally characterized. Here we report the characterization of AtbHLH68 and show that, although the knock out mutant did not have an obvious development phenotype, it was slightly more sensitive to drought stress than the Col-0, and AtbHLH68 overexpressing lines displayed defects in lateral root (LR) formation and a significant increased tolerance to drought stress, likely related to an enhanced sensitivity to abscisic acid (ABA) and/or increased ABA content. AtbHLH68 was expressed in the vascular system of Arabidopsis and its expression was modulated by exogenously applied ABA in an organ-specific manner. We showed that the expression of genes involved in ABA metabolism [AtAAO3 (AtALDEHYDE OXIDASE 3) and AtCYP707A3 (AtABSCISIC ACID 8'HYDROXYLASE 3)], in ABA-related response to drought-stress (AtMYC2, AtbHLH122 and AtRD29A) or during LRs development (AtMYC2 and AtABI3) was de-regulated in the overexpressing lines. We propose that AtbHLH68 has a function in the regulation of LR elongation, and in the response to drought stress, likely through an ABA-dependent pathway by regulating directly or indirectly components of ABA signaling and/or metabolism.
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, 78000, France.
authors.forename: Rozenn
authors.identifier: http://orcid.org/0000-0001-6076-5863
authors.initials: R
authors.lastname: Le Hir
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, 90187, Sweden.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Castelain
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, 90187, Sweden.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Chakraborti
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, 90187, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Moritz
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, 78000, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dinant
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, 78000, France.|Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, 90183, Sweden.
authors.forename: Catherine
authors.initials: C
authors.lastname: Bellini
mesh_terms: D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D014157:Transcription Factors; D000040:Abscisic Acid