The protein kinase SOS2 (Salt Overly Sensitive 2) is essential for salt-stress signaling and tolerance in Arabidopsis. SOS2 is known to be activated by calcium-SOS3 and by phosphorylation at its activation loop. SOS2 is autophosphorylated in vitro, but the autophosphorylation site and its role in salt tolerance are not known. In this study, we identified an autophosphorylation site in SOS2 and ...

The perception of abiotic stresses and signal transduction to switch on adaptive responses are critical steps in determining the survival and reproduction of plants exposed to adverse environments. Plants have stress-specific adaptive responses as well as responses which protect the plants from more than one environmental stress. There are multiple stress perception and signalling pathways, som...

Maintaining low levels of sodium ions in the cell cytosol is critical for plant growth and development. Biochemical studies suggest that Na(+)/H(+) exchangers in the plasma membrane of plant cells contribute to cellular sodium homeostasis by transporting sodium ions out of the cell; however, these exchangers have not been identified at the molecular level. Genetic analysis has linked components...

The plant SOS2 family of protein kinases and their interacting activators, the SOS3 family of calcium-binding proteins, function together in decoding calcium signals elicited by different environmental stimuli. SOS2 is activated by Ca-SOS3 and subsequently phosphorylates the ion transporter SOS1 to bring about cellular ion homeostasis under salt stress. In addition to possessing the kinase acti...

Protein phosphatase 2A (PP2A) is an enzyme consisting of three subunits: a scaffolding A subunit, a regulatory B subunit and a catalytic C subunit. PP2As were shown to play diverse roles in eukaryotes. In this study, the function of the Arabidopsis PP2A-C5 gene that encodes the catalytic subunit 5 of PP2A was studied using both loss-of-function and gain-of-function analyses. Loss-of-function mu...

The perception of abiotic stresses and signal transduction to switch on adaptive responses are critical steps in determining the survival and reproduction of plants exposed to adverse environments. Plants have stress-speci®c adaptive responses as well as responses which protect the plants from more than one environmental stress. There are multiple stress perception and signalling pathways, some...

Two Arabidopsis thaliana extragenic mutations that suppress NaCl hypersensitivity of the sos3-1 mutant were identified in a screen of a T-DNA insertion population in the genetic background of Col-0 gl1 sos3-1. Analysis of the genome sequence in the region flanking the T-DNA left border indicated that sos3-1 hkt1-1 and sos3-1 hkt1-2 plants have allelic mutations in AtHKT1. AtHKT1 mRNA is more ab...

Genetic and physiological data establish that Arabidopsis AtHKT1 facilitates Na(+) homeostasis in planta and by this function modulates K(+) nutrient status. Mutations that disrupt AtHKT1 function suppress NaCl sensitivity of sos1-1 and sos2-2, as well as of sos3-1 seedlings grown in vitro and plants grown in controlled environmental conditions. hkt1 suppression of sos3-1 NaCl sensitivity is li...

Salinity is considered a global threat to agriculture and causes significant reduction in crop yield. In particular, salinity stress promotes reactive oxygen species (ROS) accumulation ionic imbalance cells, leading oxidative even cell death. A large number of genes which are involved defense, hormone, carbohydrate metabolic pathways down-regulated under stress. Plants respond through series ph...

All plants sense and adapt to adverse environmental conditions, however, crop plants exhibit less genetic diversity for abiotic stress tolerance than do wild relatives indicating that a genetic basis exists for stress adaptability. Model plant genetic systems and the plethora of molecular genetic resources that are currently available are greatly enhancing our ability to identify abiotic stress...