Metabolic profiling and gene expression analyses provide insights into cold adaptation of an Antarctic moss Pohlia nutans

Mechanisms of Gills Response to Cadmium Exposure in Greenfin Horse-Faced Filefish (Thamnaconus septentrionalis): Oxidative Stress, Immune Response, and Energy Metabolism

Cadmium (Cd) pollution has become a global issue due to industrial and agricultural developments. However, the molecular mechanism of Cd-induced detrimental effects and relevant signal transduction/metabolic networks are largely unknown in marine fishes. Here, greenfin horse-faced filefish (Thamnaconus septentrionalis) were exposed to 5.0 mg/L Cd up to 7 days. We applied both biochemical methods and multi-omics techniques to investigate how the gills respond to Cd exposure. Our findings revealed that Cd exposure caused the formation of reactive oxygen species (ROS), which in turn activated the MAPK and apoptotic pathways to alleviate oxidative stress and cell damage. Glycolysis, protein degradation, as well as fatty acid metabolism might assist to meet the requirements of nutrition and energy under Cd stress. We also found that long-term (7 days, "long-term" means compared to 12 and 48 h) Cd exposure caused the accumulation of succinate, which would in turn trigger an inflammatory response and start an immunological process. Moreover, ferroptosis might induce inflammation. Overall, Cd exposure caused oxidative stress, energy metabolism disturbance, and immune response in greenfin horse-faced filefish. Our conclusions can be used as references for safety risk assessment of Cd to marine economic fishes.

How the xerophytic moss Pogonatum inflexum tolerates desiccation

KEY MESSAGE

Desiccation-tolerant process of xerophytic moss Pogonatum inflexum were identified through de novo transcriptome assembly , morphological structure and physiology analysis. Pogonatum inflexum (Lindb.) Lac. is a typical xerophytic moss and have been widely used in gardening and micro-landscape. However, the mechanisms underlying desiccation tolerance are still unclear. In this study, morphological,  physiological and trancriptomic analyses of P. inflexum to tolerate desiccation were carried out. Our results indicate that P. inflexum increase osmoregulation substances, shut down photosynthesis, and alter the content of membrane lipid fatty acids in response to desiccation, and the genes involved in these biological processes were changes in expression after desiccation. 12 h is the threshold for P. inflexum to tolerate desiccation and its photosynthesis has not been damaged within 12 h of desiccation and can still recover after rewater. We also proved that the gametocyte of P. inflexum has the ability to absorb and transport water, and contains lignin-synthesis genes in response to tolerant desiccation. Our findings not only explain the mechanisms of P. inflexum during desiccation, but also provide some attractive candidate genes for genetic breeding.

Combined genomic and transcriptomic analysis reveals the contribution of tandem duplication genes to low-temperature adaptation in perennial ryegrass

Perennial ryegrass (Lolium perenne L.) is an agronomically important cool-season grass species that is widely used as forage for ruminant animal production and cultivated in temperate regions for the establishment of lawns. However, the underlying genetic mechanism of the response of L. perenne to low temperature is still unclear. In the present study, we performed a comprehensive study and identified 3,770 tandem duplication genes (TDGs) in L. perenne, and evolutionary analysis revealed that L. perenne might have undergone a duplication event approximately 7.69 Mya. GO and KEGG pathway functional analyses revealed that these TDGs were mainly enriched in photosynthesis, hormone-mediated signaling pathways and responses to various stresses, suggesting that TDGs contribute to the environmental adaptability of L. perenne. In addition, the expression profile analysis revealed that the expression levels of TDGs were highly conserved and significantly lower than those of all genes in different tissues, while the frequency of differentially expressed genes (DEGs) from TDGs was much higher than that of DEGs from all genes in response to low-temperature stress. Finally, in-depth analysis of the important and expanded gene family indicated that the members of the ELIP subfamily could rapidly respond to low temperature and persistently maintain higher expression levels during all low temperature stress time points, suggesting that ELIPs most likely mediate low temperature responses and help to facilitate adaptation to low temperature in L. perenne. Our results provide evidence for the genetic underpinning of low-temperature adaptation and valuable resources for practical application and genetic improvement for stress resistance in L. perenne.

Genome-wide identification of the B3 gene family in soybean and the response to melatonin under cold stress

INTRODUCTION

Melatonin is a multipotent molecule that exists widely in animals and plants and plays an active regulatory role in abiotic stresses. The B3 superfamily is a ubiquitous transcription factor with a B3 functional domain in plants, which can respond temporally to abiotic stresses by activating defense compounds and plant hormones. Despite the fact that the B3 genes have been studied in a variety of plants, their role in soybean is still unknown.

METHODS

The regulation of melatonin on cold resistance of soybean and the response of B3 genes to cold stress were investigated by measuring biochemical indexes of soybean. Meanwhile, the genome-wide identification of B3 gene family was conducted in soybean, and B3 genes were analyzed based on phylogeny, motifs, gene structure, collinearity, and cis-regulatory elements analysis.

RESULTS

We found that cold stress-induced oxidative stress in soybean by producing excessive reactive oxygen species. However, exogenous melatonin treatment could increase the content of endogenous melatonin and other hormones, including IAA and ABA, and enhance the antioxidative system, such as POD activity, CAT activity, and GSH/GSSG, to scavenge ROS. Furthermore, the present study first revealed that melatonin could alleviate the response of soybean to cold stress by inducing the expression of B3 genes. In addition, we first identified 145 B3 genes in soybean that were unevenly distributed on 20 chromosomes. The B3 gene family was divided into 4 subgroups based on the phylogeny tree constructed with protein sequence and a variety of plant hormones and stress response cis-elements were discovered in the promoter region of the B3 genes, indicating that the B3 genes were involved in several aspects of the soybean stress response. Transcriptome analysis and results of qRT-PCR revealed that most GmB3 genes could be induced by cold, the expression of which was also regulated by melatonin. We also found that B3 genes responded to cold stress in plants by interacting with other transcription factors.

DISCUSSION

We found that melatonin regulates the response of soybean to cold stress by regulating the expression of the transcription factor B3 gene, and we identified 145 B3 genes in soybean. These findings further elucidate the potential role of the B3 gene family in soybean to resist low-temperature stress and provide valuable information for soybean functional genomics study.

Insights into the Jasmonate Signaling in Basal Land Plant Revealed by the Multi-Omics Analysis of an Antarctic Moss Pohlia nutans Treated with OPDA

12-oxo-phytodienoic acid (OPDA) is a biosynthetic precursor of jasmonic acid and triggers multiple biological processes from plant development to stress responses. However, the OPDA signaling and relevant regulatory networks were largely unknown in basal land plants. Using an integrated multi-omics technique, we investigated the global features in metabolites and transcriptional profiles of an Antarctic moss (Pohlia nutans) in response to OPDA treatment. We detected 676 metabolites based on the widely targeted metabolomics approach. A total of 82 significantly changed metabolites were observed, including fatty acids, flavonoids, phenolic acids, amino acids and derivatives, and alkaloids. In addition, the transcriptome sequencing was conducted to uncover the global transcriptional profiles. The representative differentially expressed genes were summarized into functions including Ca2+ signaling, abscisic acid signaling, jasmonate signaling, lipid and fatty acid biosynthesis, transcription factors, antioxidant enzymes, and detoxification proteins. The integrated multi-omics analysis revealed that the pathways of jasmonate and ABA signaling, lipid and fatty acid biosynthesis, and flavonoid biosynthesis might dominate the molecular responses to OPDA. Taken together, these observations provide insights into the molecular evolution of jasmonate signaling and the adaptation mechanisms of Antarctic moss to terrestrial habitats.