Abstract
Cold tolerant plants acquire freezing tolerance in response to exposure to non-freezing temperature. In higher plants, cold stress can cause increased accumulation of ABA, which could affect the signaling and regulatory pathways that direct the low temperature responses. In contrast, the role of ABA in cold acclimation process is not clearly understood in bryophytes. Protonema cells of the moss P.patens acquire freezing tolerance in response to cold and ABA treatment. In this study, we examined effects of low temperature treatment on freezing tolerance of the mutant and transgenic lines of P.patens. Low temperature treatment for seven days of wild type plants increased the freezing tolerance significantly but the treatment had little effect on that of ABA-insensitive lines. Protein and sugar analyses indicated that cold treatment induces accumulation of specific LEA-like proteins and soluble sugars in wild type, whereas the treatment increased only soluble sugars but not LEA-like proteins in the ABA-insensitive lines. These results indicate that low temperature affects ABA signaling in P.patens,leading accumulation of LEA-like proteins, which are required for freezing tolerance.
