Functional analysis of AP2 transcription factors from the dominant Antarctic moss Sanionia uncinata

Abstract

Antarctica is one of the most extreme conditions for plant growth and its vegetation is mainly dominated by bryophytes. The mosses in Antarctica grow mostly in coastal areas and are expected to have developed various unique physiological/molecular mechanisms to survive in extreme environments. Sanionia uncinata (Hypnales; Amblystegiaceae) is a dominant moss species in the maritime Antarctic and considered as a good target species to investigate genes associated with abiotic stress tolerance of mosses. In this study, we aimed to select and characterize function of a key transcription factor which induces the cold tolerance process in S. uncinata at the molecular level. Based on the transcriptome analysis, we could find twenty genes containing AP2 DNA binding domain, showing transcriptional induction in response to cold stress treatment (2℃). To characterize their functions related to cold tolerance, we generated transgenic plants which constitutively express SuAPL genes using the model moss Physcomitrella patens, exhibiting significantly lower cold tolerance than the Antarctic moss. Some of transgenic mosses displayed enhanced freezing tolerance in terms of electrolyte leakage under freezing conditions, compared to wild-type. In addition, their protonemal growth was accelerated below 8℃ indicating enhanced cold tolerance, while the gametophore development was considerably retarded. These results suggest that SuAPL have important functions in cold adaption of Sanionia uncinata to extreme Antarctic environments and they can cause multiple effects in abiotic stress tolerance and in stem cell development of mosses as well.