Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters

Abstract

Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker’s yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive structure-function studies for ion transporting proteins. Moreover, yeast can also be used as a high-throughput platform for the identification of genes that confer stress tolerance and for the study of protein–protein interactions. In this review, we summarize advances regarding potassium and sodium transport that have been discovered using the yeast model system, the state-of-the-art of the available techniques and the future directions and opportunities in this field.

Functional Characterization of a Sugar Beet BvbHLH93 Transcription Factor in Salt Stress Tolerance

“…When plants are exposed to a saline environment, Na + can enter cells through non-selective cation channels and K+ transporters. Thus, maintaining ion homeostasis is imperative for plants to adapt to salt stress [ 20 ]. In this study, the OX lines maintained significantly higher K + /Na + ratios than the WT under salt stress ( Figure 5 c).…”

Adaptation of Plants to Salt Stress: Characterization of Na+ and K+ Transporters and Role of CBL Gene Family in Regulating Salt Stress Response

“…The only member of the HKT family in Arabidopsis, orthologue of the wheat TaHKT1 gene, has been identified and designated as AtHKT1. The expression of this gene in yeast strains lacking the Na + efflux system aggravates their sensitivity to Na + , but it does not suppress K + transport deficiency in trk1 and trk2 mutants that have difficulty to absorb potassium [112] When expressed in the Xenopus oocyte, AtHKT1 exhibits strictly selective Na + transport activity, without any permeability to K + . Similarly, AtHKT1expression does not complement a type of E. coli mutant unable to absorb K + , which helps to show that AtHKT1 carries only Na + .…”

Physiological and Molecular Characterization of the Differential Response of Broccoli (Brassica oleracea var. Italica) Cultivars Reveals Limiting Factors for Broccoli Tolerance to Drought Stress

“…To avoid this problem, several experimental designs have proven to be effective, such as screening for genes in heterologous systems. 9 , 10 However, to take advantage of this knowledge, new GMO crops must be developed, which is still a problem to market in many countries and requires a long and expensive process of regulation prior to approval.…”