Investigating the molecular mechanism whereby auxin modulates Arabidopsis thaliana growth under salinity stress conditions
type: CreativeWork
description: Soil salinization is detrimental to plant growth and yield, and an increasing global problem in irrigated agricultural land. Salinity imposes both an osmotic and ionic stress on plants, the latter of which is unique to salt stress. Previous work has indicated that the plant growth hormone auxin could play an important role in ionic stress tolerance: transcriptome profiling revealed that the genes differentially expressed in response to ionic stress were enriched with the gene ontology term ‘Response to auxin'. Additionally, expression of the auxin biosynthesis gene, Nitrilase 2 (NIT2), was also specifically up-regulated in response to ionic stress. A NIT2 overexpressing line (35S::NIT2) has been shown to display improved germination and growth, as well as increased auxin levels compared to wild-type plants under saline conditions. The hypothesis thus is that salt stress induces NIT2 expression, thereby increasing auxin biosynthesis, which results in the activation of the plasma membrane (PM) H+-ATPase pump and subsequent activation of expansion growth mediated by expansins. Additionally, the pump activation could enhance the proton motive force for ion transport across the PM, thereby affecting ion homeostasis during salt stress. The aim of this study was to investigate this proposed molecular mechanism whereby auxin modulates plant growth in response to salt stress. Measurement of Na+ and K+ content revealed that 35S::NIT2 plants had improved root and shoot Na+/K+ ratios compared with wild-type (No-0 ecotype) plants, under saline conditions. This altered ion homeostasis might be a consequence of differences in the expression of several Na+ and K+ transporter/channel genes between the two lines. Of particular interest, under saline conditions, the 35S::NIT2 line had increased root HKT1;1, AKT1, and SKOR expression, as well as decreased GLR2.3 expression; and increased shoot NHX3, SOS1, and KUP1 expression. Together these results provide evidence that improved Na+/K+…
abstract: Soil salinization is detrimental to plant growth and yield, and an increasing global problem in irrigated agricultural land. Salinity imposes both an osmotic and ionic stress on plants, the latter of which is unique to salt stress. Previous work has indicated that the plant growth hormone auxin could play an important role in ionic stress tolerance: transcriptome profiling revealed that the genes differentially expressed in response to ionic stress were enriched with the gene ontology term ‘Response to auxin'. Additionally, expression of the auxin biosynthesis gene, Nitrilase 2 (NIT2), was also specifically up-regulated in response to ionic stress. A NIT2 overexpressing line (35S::NIT2) has been shown to display improved germination and growth, as well as increased auxin levels compared to wild-type plants under saline conditions. The hypothesis thus is that salt stress induces NIT2 expression, thereby increasing auxin biosynthesis, which results in the activation of the plasma membrane (PM) H+-ATPase pump and subsequent activation of expansion growth mediated by expansins. Additionally, the pump activation could enhance the proton motive force for ion transport across the PM, thereby affecting ion homeostasis during salt stress. The aim of this study was to investigate this proposed molecular mechanism whereby auxin modulates plant growth in response to salt stress. Measurement of Na+ and K+ content revealed that 35S::NIT2 plants had improved root and shoot Na+/K+ ratios compared with wild-type (No-0 ecotype) plants, under saline conditions. This altered ion homeostasis might be a consequence of differences in the expression of several Na+ and K+ transporter/channel genes between the two lines. Of particular interest, under saline conditions, the 35S::NIT2 line had increased root HKT1;1, AKT1, and SKOR expression, as well as decreased GLR2.3 expression; and increased shoot NHX3, SOS1, and KUP1 expression. Together these results provide evidence that improved Na+/K+…
author: Ferrandi, Paul
keywords: Molecular and Cell Biology
date published: 2023
date modified: 2026-07-22T22:23:19Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Molecular and Cell Biology

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/39526