Abstract
Bryophytes are the dominant vegetation in the Antarctic continent. They have suffered more unpleasant ultraviolet radiation due to the Antarctic ozone layer destruction. However, it remains unclear about the molecular mechanism of Antarctic moss acclimation to UV-B light. Here, the transcriptomics and metabolomics approaches were conducted to uncover transcriptional and metabolic profiling of the Antarctic moss Leptobryum pyriforme under UV-B radiation. Totally, 67,290 unigenes with N50 length of 2,055 bp were assembled. Of them, 1,594 unigenes were significantly up-regulated and 3353 unigenes were markedly down-regulated under UV-B radiation. These differentially expressed genes (DEGs) involved in UV-B signaling, flavonoid biosynthesis, ROS scavenging, and DNA repair. In addition, a total of 531 metabolites were detected, while flavonoids and anthocyanins accounted for 10.36% of the total compounds. There were 49 upregulated metabolites and 41 downregulated metabolites under UV-B radiation. Flavonoids were the most significantly changed metabolites. qPCR analysis showed that UVR8-COP1-HY5 signaling pathway genes and photolyase genes (i.e., LpUVR3, LpPHR1, and LpDPL) were significantly up-regulated under UV-B light. In addition, the expression levels of JA signaling pathway-related genes (i.e., OPR and JAZ) and flavonoid biosynthesis-related genes were also significantly increased under UV-B radiation. The integrative data analysis showed that UVR8-mediated signaling, jasmonate signaling, flavonoid biosynthesis pathway and DNA repair system might contribute to L. pyriforme acclimating to UV-B radiation. Therefore, these findings present a novel knowledge for understanding the adaption of Antarctic moss to polar environments and provide a foundation for assessing the impact of global climate change on Antarctic land plants.
Highlights
Ultraviolet-B radiation (280–315 nm) is an inherent part of sunlight
These differentially expressed genes (DEGs) can be further classified into pathways of UV-B signaling and DNA repair system [e.g., (6–4) DNA photolyase, type II CPD DNA photolyase, deoxyribodipyrimidine photolyase, DNA repair endonuclease UVH1, and formamidopyrimidine DNA glycosylase], flavonoid biosynthesis, jasmonic acid signaling (12oxophytodienoate reductase 3, jasmonate ZIM domain protein, and WD repeat-containing protein RUP2) (Table 2)
The moss model plant P. patens was found to be more capable of surviving UV-B stress than Arabidopsis and approximately 400 differential expression genes were identified from moss in response to UVB radiation (Wolf et al, 2010)
Summary
Ultraviolet-B radiation (280–315 nm) is an inherent part of sunlight. Increased UV-B light have been observed on the earth’s surface since the 1980s and 1990s due to depletion of stratospheric ozone layer, which results from increases of chlorofluorocarbons in the atmosphere (Hossaini et al, 2017; Neale et al, 2021). Flavonoids and carotenoids extracted from three Antarctic species [i.e., Polytrichum juniperinum Hedw, Colobanthus quitensis (Kunth) Bartl, and Deschampsia antarctica Desv] demonstrated the characteristics of UV-absorbing compounds, protecting cells and activating the DNA damage repair process (Pereira et al, 2009). It seems that these basal land plants can fight against the UV-B radiation through synthesizing antioxidants including UV-B-absorbing pigments, flavonoids and anthocyanins, functioning as the effective damage repair systems (Singh et al, 2011). Our evidence confirmed that anthocyanins compounds were present in the Antarctic moss L. pyriforme
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