Roles of Arabidopsis thaliana Na+/H+ Antiporters NHX2 and NHX3 in Potassium Ion Homeostasis

Student Name: Athena Kan

UCD Department: Plant Sciences

UCD Mentor: Dr. Eduardo Blumwald

Antiporters are generally responsible for ion homeostasis in the model organism Arabidopsis thaliana by exchanging hydrogen ions (H+) for sodium (Na+) or potassium (K+). However, information regarding the role of NHX2 and NHX3 in this process is scarce; therefore, this study aims to investigate the effect of overexpression of NHX and NHX3 genes individually when the plant is grown in Spalding media with varying concentrations of potassium: 30mM (high), 1mM (medium), and 0.1mM (low). After ten days of growth, root length was measured and then expression of HAK5 and AKT1, which correlate with low levels and high levels of potassium, respectively, were measured using comparative qPCR analysis. The results indicated that though overexpression of the NHX2 gene had little to no effect in any concentration of potassium media, overexpression of the NHX3 gene significantly impacted growth and development. Specimens with an overexpressed NHX3 gene exhibited shorter roots, increased expression of HAK5, and decreased expression of AKT1 in low levels of potassium. Not only do these results present a better understanding of Arabidopsis thaliana, but they may also guide the process of developing better stress response capabilities in crops; abiotic stress is the primary cause of crop loss worldwide.