title: Endodermal ABA signaling promotes lateral root quiescence during salt stress in Arabidopsis seedlings.
abstract: The endodermal tissue layer is found in the roots of vascular plants and functions as a semipermeable barrier, regulating the transport of solutes from the soil into the vascular stream. As a gateway for solutes, the endodermis may also serve as an important site for sensing and responding to useful or toxic substances in the environment. Here, we show that high salinity, an environmental stress widely impacting agricultural land, regulates growth of the seedling root system through a signaling network operating primarily in the endodermis. We report that salt stress induces an extended quiescent phase in postemergence lateral roots (LRs) whereby the rate of growth is suppressed for several days before recovery begins. Quiescence is correlated with sustained abscisic acid (ABA) response in LRs and is dependent upon genes necessary for ABA biosynthesis, signaling, and transcriptional regulation. We use a tissue-specific strategy to identify the key cell layers where ABA signaling acts to regulate growth. In the endodermis, misexpression of the ABA insensitive1-1 mutant protein, which dominantly inhibits ABA signaling, leads to a substantial recovery in LR growth under salt stress conditions. Gibberellic acid signaling, which antagonizes the ABA pathway, also acts primarily in the endodermis, and we define the crosstalk between these two hormones. Our results identify the endodermis as a gateway with an ABA-dependent guard, which prevents root growth into saline environments.
authors: Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305, USA.
authors: Lina
authors: L
authors: Duan
authors: Daniela
authors: D
authors: Dietrich
authors: Chong Han
authors: CH
authors: Ng
authors: Penny Mei Yeen
authors: PM
authors: Chan
authors: Rishikesh
authors: R
authors: Bhalerao
authors: Malcolm J
authors: MJ
authors: Bennett
authors: José R
authors: JR
authors: Dinneny
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009928:Organ Specificity; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D019441:Plant Epidermis / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D005875:Gibberellins; D010937:Plant Growth Regulators; D012965:Sodium Chloride; D000040:Abscisic Acid; C007842:gibberellic acid; C087434:ABI1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases