Potassium (K+) is the most abundant inorganic cation in plants, and molecular dissection of K+deficiency has received considerable interest in order to minimize K+fertilizer input and develop high quality K+-efficient crops. However, the molecular mechanism of plant responses to K+deficiency is still poorly understood. In this study, 2-week-old bread wheat seedlings grown hydroponically in Hoagland solution were transferred to K+-free conditions for 8 d, and their root and leaf proteome profiles were assessed using the iTRAQ proteome method. Over 4000 unique proteins were identified, and 818 K+-responsive protein species showed significant differences in abundance. The differentially expressed protein species were associated with diverse functions and exhibited organ-specific differences. Most of the differentially expressed protein species related to hormone synthesis were involved in jasmonic acid (JA) synthesis and the upregulated abundance of JA synthesis-related enzymes could result in the increased JA concentrations. Abundance of allene oxide synthase (AOS), one key JA synthesis-related enzyme, was significantly increased in K+-deficient wheat seedlings, and its overexpression markedly increased concentrations of K+and JA, altered the transcription levels of some genes encoding K+-responsive protein species, as well as enhanced the tolerance of rice plants to low K+or K+deficiency. Moreover, rice AOS mutant (osaos) exhibited more sensitivity to low K+or K+deficiency. Our findings could highlight the importance of JA in K+deficiency, and imply a network of molecular processes underlying plant responses to K+deficiency.