ABSTRACT
The members of early auxin response gene family, Aux/IAA, encode negative regulators of auxin signaling but play a central role in auxin-mediated plant development. Here we report the interaction of an Aux/IAA protein, AtIAA14, with Drought-induced-19 (Di19-3) protein and its possible role in auxin signaling. The Atdi19-3 mutant seedlings develop short hypocotyl, both in light and dark, and are compromised in temperature-induced hypocotyl elongation. The mutant plants accumulate more IAA and also show altered expression of NIT2, ILL5, and YUCCA genes involved in auxin biosynthesis and homeostasis, along with many auxin responsive genes like AUX1 and MYB77. Atdi19-3 seedlings show enhanced root growth inhibition when grown in the medium supplemented with auxin. Nevertheless, number of lateral roots is low in Atdi19-3 seedlings grown on the basal medium. We have shown that AtIAA14 physically interacts with AtDi19-3 in yeast two-hybrid (Y2H), bimolecular fluorescence complementation, and in vitro pull-down assays. However, the auxin-induced degradation of AtIAA14 in the Atdi19-3 seedlings was delayed. By expressing pIAA14::mIAA14-GFP in Atdi19-3 mutant background, it became apparent that both Di19-3 and AtIAA14 work in the same pathway and influence lateral root development in Arabidopsis. Gain-of-function slr-1/iaa14 (slr) mutant, like Atdi19-3, showed tolerance to abiotic stress in seed germination and cotyledon greening assays. The Atdi19-3 seedlings showed enhanced sensitivity to ethylene in triple response assay and AgNO3, an ethylene inhibitor, caused profuse lateral root formation in the mutant seedlings. These observations suggest that AtDi19-3 interacting with AtIAA14, in all probability, serves as a positive regulator of auxin signaling and also plays a role in some ethylene-mediated responses in Arabidopsis. SIGNIFICANCE STATEMENT: This study has demonstrated interaction of auxin responsive Aux/IAA with Drought-induced 19 (Di19) protein and its possible implication in abiotic stress response.
ABSTRACT
Abiotic stresses like drought, salinity, high and low temperature, and submergence are major factors that limit the crop productivity. Hence, identification of genes associated with stress response in crops is a prerequisite for improving their tolerance to adverse environmental conditions. In an earlier study, we had identified a drought-inducible gene, vesicle-associated membrane protein-associated protein (TaVAP), in developing grains of wheat. In this study, we demonstrate that TaVAP is able to complement yeast and Arabidopsis mutants, which are impaired in their respective orthologs, signifying functional conservation. Constitutive expression of TaVAP in Arabidopsis imparted tolerance to water stress conditions without any apparent yield penalty. Enhanced tolerance to water stress was associated with maintenance of higher relative water content, photosynthetic efficiency, and antioxidant activities. Compared to wild type, the TaVAP-overexpressing plants showed enhanced lateral root proliferation that was attributed to higher endogenous levels of IAA. These studies are the first to demonstrate that TaVAP plays a critical role in growth and development in plants, and is a potential candidate for improving the abiotic stress tolerance in crop plants.
Subject(s)
Adaptation, Physiological/genetics , Droughts , Genes, Plant , Plant Proteins/genetics , R-SNARE Proteins/genetics , Stress, Physiological/genetics , Triticum/genetics , Triticum/physiology , Antioxidants/metabolism , Arabidopsis/genetics , Catalase/metabolism , Gene Expression Regulation, Plant/drug effects , Genetic Complementation Test , Indoleacetic Acids/metabolism , Malondialdehyde/metabolism , Peroxidase/metabolism , Phenotype , Photosynthesis/drug effects , Plant Growth Regulators/pharmacology , Plant Leaves/drug effects , Plant Proteins/metabolism , Plant Roots/drug effects , Plant Roots/metabolism , R-SNARE Proteins/metabolism , Saccharomyces cerevisiae/genetics , Stress, Physiological/drug effects , Triticum/drug effectsABSTRACT
Growth at high temperatures is one of the desired features for industrial applications of microbes, as it results in decrease in contamination and enhanced solubility of certain substrates. In this study, it is demonstrated that heterologous expression of a wheat cyclophilin, TaCypA-1, confers thermotolerance to Escherichia coli. The TaCypA-1 possesses peptidyl-prolyl cis-trans isomerase (PPIase) activity that catalyses cis to trans isomerization of the peptidyl prolyl bonds, a rate limiting step in protein folding. Expression of deleted mutants of TaCypA-1, that lacked PPIase activity, resulted in abrogation of thermotolerance, providing the first evidence that this activity plays a key role in stress tolerance of cells and can be exploited for industrial applications. Further, we also demonstrate that TaCypA-1 interacts with calmodulin (CaM), and the CaM-binding domain is localized to amino acid residues 51-71 in the N-terminus region.
ABSTRACT
The gene encoding eIF3g (TaeIF3g), one of the 11 subunits of eukaryotic translation initiation factor 3 (eIF3), was cloned from wheat for carrying out its functional analysis. Transgenic expression of TaeIF3g enhanced the tolerance of TaeIF3g-overexpressing parental yeast cells and Arabidopsis plants under different abiotic stress conditions. Compared to untransformed plants, TaeIF3g-overexpressing Arabidopsis thaliana plants exhibited significantly higher survival rate, soluble proteins and photosynthetic efficiency, and enhanced protection against photooxidative stress under drought conditions. This study provides first evidence that TaeIF3g imparts stress tolerance and could be a potential candidate gene for developing crop plants tolerant to abiotic stress.
