De novo assembly and transcriptome analysis of the moss Sanionia uncinata in response to relative water content reduction in Antarctic natural habitat

Abstract

If the recent global warming trend observed on the Antarctic Peninsula persists over the long term, increasing aridity is expected, due to the loss of glaciers that act as the main source of available water. However, the molecular responses of Antarctic mosses to this possible future decrease in water availability have not yet been investigated. Thus, we evaluated the photochemical response to a decreasing relative water content (RWC) in Sanionia uncinata, the dominant moss species in the maritime Antarctic. As aridity increased, chlorophyll contents and the values of several photochemical parameters decreased, indicating that S. uncinata is sensitive to drought and that their productivity will be negatively affected by increased aridity. Subsequently, we assembled a de novo transcriptome comprising 32,100 unigenes and analyzed their expression patterns along the RWC gradient. In the significantly up-regulated group including 64 unigenes, we found genes with functions related to ‘secondary metabolism’ and ‘response to stimulus.’ Meanwhile, in the down-regulated group including 323 genes, we found more ‘response to stimulus’ genes, and genes related to ‘photosynthesis’ and ‘transport’ were also significantly repressed. Our results suggested that RWC reductions decreased the photosynthetic activity and chlorophyll content of S. uncinata, and had a negative effect at the transcription level on structural proteins of the photosynthetic apparatus, leading to photosynthetic inhibition. Moreover, the transcriptomic dataset created in this study provides a valuable resource for comparative genomic or transcriptomic studies of bryophytes, for which omics data are currently very limited.