Abstract: We isolated six putative PpeKEA（K+ efflux antiporter）genes from peach flowers，and analyzed the transcriptional expression and response to potassium（K+）fertilizer application during different flowering stages. Key antiporter genes were obtained and functionally verified. K+ fertilizer application favorably enhanced the flower fresh weight of‘Xiahui 8’peach in full bloom stage，and strengthened the flower K+ nutritional status. PpeKEA1–PpeKEA6 were differentially expressed during four stages，and the highest expression level appeared especially in full bloom stage. PpeKEA genes were differentially regulated by K+ fertilizer treatment. Notably，PpeKEA1 was the most highly expressed gene throughout the whole flowering process，which was significantly up-regulated in bud period and begin bloom stages but reduced in petal fall stage by K2O treatment. The recombinant expression vector pDR196-shortKEA1 can mediate K+ homeostasis in AXT3 yeast mutant，indicating that expression level of PpeKEA1 was positively correlated with the K+ homeostasis in peach flowering process. This study revealed that PpeKEA1 was an important K+/H+ antiporter that may regulate K+ homeostasis during the peach flowering，which contributes to K+/H+ balance and K+ homeostasis in fruit trees.

Key words: peach, flowering, K+/H+ antiporter, K+ fertilizer, ATX3 yeast mutant, functional validation