Abstract:

To explore physiological and molecular mechanisms of apple dwarfing rootstock，we analyzed the characteristics of physiochemistry，including membrane injury，reactive oxygen metabolism and osmotic adjustment substances accumulation，and transcriptome profiling occurred in‘71-3-150’，a cold-resistant apple dwarfing rootstock originated from Russia，exposed to cold stress（4 ℃）for 0，2，6，12 and 24 h. We found the immediate antioxidant and osmotic adjustment response of the rootstock to cold stress emerged during the first 2 h of cold exposure. Activities of reactive oxygen-scavenging enzymes SOD and CAT，and contents of main osmotic adjustment substances plateaued after 6 h of cold. Meanwhile，aggravating trend of membrane injury was mitigating，indicating the rapid physiological response of the rootstock to cold. The initial 6 h could be critical period for cold acclimation of the rootstock. Based on transcriptome analysis，491，1 115，828 and 1 047 up regulated differentially expressed genes（DEGs）and 537，688，708 and 1 016 down regulated DEGs were identified in 2，6，12 and 24 h samples respectively，compared with 0 h sample. The common 115 up and 136 down regulated DEGs showed 6 expression patterns. Twenty-eight functional and regulatory DEGs were screened out. These genes involved in stress signals reception and transduction showed obvious up-regulated expression in early cold stress（0–2 h），while those that took part in osmotic adjustment，reactive oxygen metabolism，and membrane and protein protection expressed with various patterns. These results suggested the rapid and multiple molecular mechanisms of perception，transduction and responses to cold stress in cold acclimation of‘71-3-150’.

Key words: apple, dwarfing rootstock, cold stress, physiology, transcriptome, cold-resistant genes