Growth Response of Eutrema salsugineum Seedlings on Media Containing Different Levels of Potassium

Abstract

Potassium (K+) is a macronutrient essential for optimum plant growth and yield. Despite its agricultural significance, farmers frequently overlook the benefits of K+ fertilizers so K+ deficiencies can develop in crops. A defined nutrient medium was devised to assess the response of seedlings of the extremophile crucifer, Eutrema salsugineum (Yukon and Shandong accessions), to conditions lacking added K+ (0 mM K+) or K+ at concentrations of 0.5 and 2.0 mM. Arabidopsis thaliana seedlings were also grown to provide a comparison to a well-documented phenotype for K+ deficiency symptoms. Due to different growth rates, the experiment ended on Days 10 and 15 for Yukon and Shandong Eutrema, respectively, compared to Day 7 for Arabidopsis. Like Arabidopsis, Eutrema shoot and root biomass was reduced in seedlings grown on media lacking K+ relative to plants on 2 mM K+ plates but the reduction in root biomass was most pronounced for Arabidopsis (5-fold) compared to Eutrema (2-fold). Eutrema had significantly shorter primary roots on 0 mM K+ plates and the 1.8-fold decrease relative to Yukon seedlings on 2 mM K+ plates was similar to the 2-fold reduction for Shandong plants. Eutrema seedlings had significantly reduced lateral root growth on 0 mM K+ plates although the 1.8-fold reduction relative to seedlings on 2 mM K+ plates was not as great as the 7-fold decrease for Arabidopsis roots. Shandong seedlings did not show K+- specific changes in root hair morphology but root hairs of Yukon seedlings were over 2- fold longer on 0 mM K+ plates compared to those of roots on 0.5 mM or 2 mM K+ plates. Overall, the data shows that Eutrema seedlings cope well with low K+ conditions but there are accession-specific differences that distinguish Yukon from Shandong plants.