Title : Living with high potassium : how plants balance nutrient acquisition during K-induced 1 salt stress 2

9 K is more toxic in plants than Na at similar concentrations but the molecular mechanisms 10 governing excess K-induced salt stress are unknown. We used Arabidopsis thaliana and its 11 extremophyte relative Schrenkiella parvula, to explore this largely unexplored question using 12 comparative physiological, ionomic, transcriptomic, and metabolomic approaches aimed at 13 understanding how plants can develop resilience to excess K. Our results showed that the stress 14 responses exhibited by the two plants diverged at a decisive step where the stress-sensitive A. 15 thaliana could not limit excess K influx and suffered severe nutrient depletion. The stress 16 adapted model, S. parvula, was able to independently regulate reduction in K uptake while 17 sustaining uptake of other major nutrients including N. Maintaining N uptake and its 18 uninterrupted assimilation into primary metabolites allowed S. parvula to sustain growth and 19 concurrently boost its antioxidant and osmolyte pools, facilitated by a targeted transcriptomic 20 response. In contrast, A. thaliana descended into mismanaged transcriptional cascades 21 including induction of biotic and abiotic stress responses and autophagy accompanied by 22 inhibited growth, reduced photosynthesis, and increased ROS. This study provides a basic 23 framework to select key pathways to target in the development of building plant resilience 24 towards nutrient imbalance caused by K-induced salt stress. 25