The natural variation in the promoter region of PdaSWEET7 results in cold tolerance in Prunus davidiana

Abstract Climate change has intensified the occurrence of freezing damage in peach ( Prunus persica ) orchards, particularly during winter dormancy, posing a major threat to sustainable peach production. Prunus davidiana , a close wild relative of peach, exhibits enhanced cold hardiness and represents a valuable genetic resource for breeding cold-tolerant cultivars. However, the mechanism underlying its superior cold adaptation remain largely unknown. In this study, comparative transcriptome analysis of 7 peach and wild relative accessions, combined with genetic transformation approaches, identified SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER 7 (SWEET7) as a key regulator of cold tolerance in P. davidiana . PdaSWEET7 was specifically induced by cold stress in P. davidiana and enhanced cold tolerance by facilitating the transport of extracellular glucose into phloem cells, thereby promoting cellular osmotic adjustment. In addition, natural variations were exclusively present in the PdaSWEET7 promoter not only increased its own promoter activity but also interacted with basic leucine zipper 9 (bZIP9) and the myelocytomatosis (MYC) transcription factor MYC2.1 under normal and cold conditions, respectively. Collectively, this study reveals a previously unknown SWEET7 -mediated mechanism responsible for cold hardiness in P. davidiana and provides valuable genetic insights for the molecular breeding of cold-tolerant peach cultivars.