Potassium (K) deficiency is a bottleneck for crop production. Thus, developing low K (LK)-tolerant crop cultivars to relieve the issue is extremely urgent. Our previous studies had found that Tibetan annual wild barley accessions showed a higher LK tolerance than the cultivated barley. In this study, RNA-sequencing was performed on three barley genotypes, wild (XZ153, LK tolerance; XZ141, LK sensitivity) and cultivated (ZD9, LK sensitivity) barley genotypes, to compare the transcriptome profiles of their shoots at two time points after LK stress. In total, 4832 genes displayed differential expression at 48 h and 15 d among three genotypes after K stress treatment, with XZ153 having much more differentially expressed genes (DEGs) at 48 h than 15 d, but it was the opposite in ZD9. Meanwhile, GO annotation analysis and KEGG pathway enrichment were implemented on 555 and 814 LK tolerance-associated DEGs at 48 h and 15 d after LK stress, respectively. Three barley genotypes differed significantly in transcriptional level after LK treatment. The high tolerance in wild genotype XZ153 could be attributed to many factors, mainly including K channels, Ca2+ signaling pathway, ethylene biosynthesis process, TCA cycle, glycolysis, pentose phosphate pathway, and photosynthesis. Furthermore, some candidate genes identified in this study may be used to improve the LK tolerance of barley.
