Integrated transcriptome and metabolome analyses reveal the adaptation of Antarctic moss Pohlia nutans to drought stress

Abstract

Most regions of the Antarctic continent are experiencing increased dryness due to global climate change. Mosses and lichens are the dominant vegetation of the ice-free areas of Antarctica. However, the molecular mechanisms of these Antarctic plants adapting to drought stress are less documented. Here, transcriptome and metabolome analyses were employed to reveal the responses of an Antarctic moss (Pohlia nutans subsp. LIU) to drought stress. We found that drought stress made the gametophytes turn yellow and curled, and enhanced the contents of malondialdehyde and proline, and the activities of antioxidant enzymes. Totally, 2,451 differentially expressed genes (DEGs) were uncovered under drought treatment. The representative DEGs are mainly involved in ROS-scavenging and detoxification, flavonoid metabolism pathway, plant hormone signaling pathway, lipids metabolism pathway, transcription factors and signal-related genes. Meanwhile, a total of 354 differentially changed metabolites (DCMs) were detected in the metabolome analysis. Flavonoids and lipids were the most abundant metabolites and they accounted for 41.53% of the significantly changed metabolites. In addition, integrated transcriptome and metabolome analyses revealed co-expression patterns of flavonoid and long-chain fatty acid biosynthesis genes and their metabolites. Finally, qPCR analysis demonstrated that the expression levels of stress-related genes were significantly increased. These genes included those involved in ABA signaling pathway (NCED3, PP2C, PYL, and SnAK2), jasmonate signaling pathway (AOC, AOS, JAZ, and OPR), flavonoid pathway (CHS, F3’,5’H, F3H, FLS, FNS, and UFGT), antioxidant and detoxifying functions (POD, GSH-Px, Prx and DTX), and transcription factors (ERF and DREB). In summary, we speculated that P. nutans were highly dependent on ABA and jasmonate signaling pathways, ROS scavenging, flavonoids and fatty acid metabolism in response to drought stress. These findings present an important knowledge for assessing the impact of coastal climate change on Antarctic basal plants.

Transcriptome sequencing and metabolome analysis reveal the molecular mechanism of Salvia miltiorrhiza in response to drought stress

“…Studies have shown that CHS is an essential rate-limiting enzyme in the pathway that produces flavonoids and is necessary for regulating plant growth, development, and abiotic stress resistance [ 73 ]. All of these results supported earlier research and indicated that the biosynthesis pathways of phenylpropanoids and flavonoids, especially CHS genes and apigenin, were involved in the response of S. miltiorrhiza to drought stress [ 20 ].…”

“…Combining transcriptome and metabolomic analyses, researchers have hypothesized that P. nutans strongly relies on the plant hormone signaling pathway and flavonoid metabolism pathway, as well as stress-related genes involved in these pathways, such as NCED3, PP2C, and PYL, which are involved in the ABA signaling pathway. In addition, stress-related genes also included AOS and JAZ in the JA signaling pathway, CHS, FLS, FNS, and UFGT in the flavonoid pathway, and transcription factors ( ERF and DRE B) [ 20 ].…”

Transcriptome analysis of the common moss Bryum pseudotriquetrum grown under Antarctic field conditions

“…This result indicates that acquisition of environmental stress tolerance in Antarctic mosses by changing fatty acid metabolism requires relatively prolonged exposure to environmental stresses. Although most previous studies using Antarctic mosses have examined changes in gene expression pro les after single arti cial stress treatments for short periods (a few hours to several days) 4,5,6,7 , longer periods of stress treatments may be required to clarify actual mechanisms of environmental stress tolerance in Antarctic mosses.…”

“…When plants are exposed to severe environments, stress response genes, such as myelocytomatosis (MYC) genes, myeloblastosis (MYB) genes, ethylene-responsive element binding factor (ERF) genes and dehydration-responsive element binding (DREB) genes, are induced, and subsequently various stress responses including expression of molecular chaperone proteins, production of antioxidants such as avonoids, accumulation of sugars and lipids, and increase in membrane uidity through increase of unsaturated fatty acids occur 1,2,3 . In Pohlia nutans, one of the mosses grown in Antarctica, changes in gene expression pro les have been investigated in response to arti cial stress treatments such as high salinity, low temperature and drought 4,5,6,7 . In these studies, expression of transcription factor genes involved in environmental stress response and tolerance (e.g., MYC, MYB, ERF and DREB genes), genes involved in signaling of plant hormones such as abscisic acid (ABA) and jasmonic acid (JA), and antioxidant biosynthesis genes have been shown to be induced by arti cial stress treatment.…”