Trehalose metabolism genes render rice white tip nematode Aphelenchoides besseyi (Nematoda: Aphelenchoididae) resistant to an anaerobic environment

The nematode Caenorhabditis elegans enhances tolerance to landfill leachate stress by increasing trehalose synthesis

The burgeoning issue of landfill leachate, exacerbated by urbanization, necessitates evaluating its biological impact, traditionally overshadowed by physical and chemical assessments. This study harnesses Caenorhabditis elegans, a model organism, to elucidate the physiological toxicity of landfill leachate subjected to different treatment processes: nanofiltration reverse osmosis tail water (NFRO), membrane bioreactor (MBR), and raw leachate (RAW). Our investigation focuses on the modulation of sugar metabolism, particularly trehalose-a disaccharide serving dual functions as an energy source and an anti-adversity molecule in invertebrates. Upon exposure, C. elegans showcased a 60-70% reduction in glucose and glycogen levels alongside a significant trehalose increase, highlighting an adaptive response to environmental stress by augmenting trehalose synthesis. Notably, trehalose-related genes in the NFRO group were up-regulated, contrasting with the MBR and RAW groups, where trehalose synthesis genes outpaced decomposition genes by 20-30 times. These findings suggest that C. elegans predominantly counters landfill leachate-induced stress through trehalose accumulation. This research not only provides insights into the differential impact of leachate treatment methods on C. elegans but also proposes a molecular framework for assessing the environmental repercussions of landfill leachate, contributing to the development of novel strategies for pollution mitigation and environmental preservation.

Trehalose in pine wood nematode participates in DJ3 formation and confers resistance to low-temperature stress

Background

Recently, pine wood nematode (PWN, Bursaphelenchus xylophilus) has been found in the extreme cold area of northeast China. The third-stage dispersal juvenile (DJ3) of PWN, which is a long-lived stress-resistant stage, plays an important role in the process of PWN spreading to low-temperature areas, as this stage can survive under unfavorable conditions.

Results

Weighted correlation network analysis (WGCNA) was used to analyze the expression patterns of 15,889 genes included in 21 RNA-Seq results of PWN at DJ3 and the other 6 different stages, and a total of 12 coexpression modules were obtained. Among them, the magenta module has the highest correlation with DJ3, which included a total of 652 genes. KEGG enrichment analysis showed that most of the genes in the magenta module were involved in metabolic processes, which were related to autophagy and longevity regulation. These pathways included starch and sucrose metabolism, which contains trehalose metabolism. To explore the function of trehalose in DJ3 formation and survival under − 20 °C, a trehalose-6-phosphate synthase encoding gene (Bx-tps), a trehalose-6-phosphate phosphatase encoding gene (Bx-tpp) and 7 trehalase encoding genes (Bx-tres) were identified and investigated. The expression of these 9 genes was related to the formation of DJ3. A treatment under − 20 °C induced the accumulation of trehalose. The survival rate of DJ3 at -20 °C reduced after silencing of any of these trehalose metabolism genes. Further analysis suggested that two trehalose synthesis genes were highly correlated with DJ3 and might be involved in autophagy by regulating with energy conversion related genes.

Conclusions

The above results indicated that trehalose metabolism promotes DJ3 formation and helps DJ3 survive at -20 °C. Although trehalose accumulation is favorable for DJ3 to cope with low-temperature stress, multiple trehalose metabolism genes need to work together. There may be a multi-path regulated physiological process involving trehalose synthesis genes under low-temperature stress resistance. This physiological process may regulate the formation and maintenance of DJ3 through autophagy and energy conversion.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07839-0.

Metabolomics of soybean green stem and foliar retention (GSFR) disease using mass spectrometry and molecular networking

RATIONALE

The nematode Aphelenchoides besseyi is the causal agent of green stem and foliar retention, a soybean disease recently described in Brazil. This condition can reduce soybean yield by up to 100%. However, little is known about chemical interactions between the plant and pathogen. Therefore, this work aimed to investigate metabolites from healthy soybean roots and from soybean roots that were inoculated with A. besseyi.

METHODS

A. besseyi were multiplied in vitro with Fusarium sp. colonies in Petri dishes for 25 days, and were axenically inoculated into hydroponics healthy soybean plants. The metabolites were extracted from the roots of healthy and A. besseyi-infected plants 16 days post-inoculation. These extracts were analyzed using an untargeted metabolomic method with an ultra-high-performance liquid chromatography/electrospray ionization /tandem mass spectrometry (UHPLC/ESI-MS/MS) and molecular networking approach.

RESULTS

Roots from infected plants showed morphological alterations such as shrinkage, darkening, and arching. Similarly, they also showed an increased presence of flavonoids, compared with healthy roots. Compounds such as neobavaisoflavone, glycitin, genistin, and genistein were putatively identified and had greater intensity in inoculated roots. These compounds are linked to the defensive mechanisms in plants against nematodes. Moreover, coumaric acid, also exclusively putatively identified in inoculated roots, shows activity related to inhibition of root growth.

CONCLUSIONS

Liquid chromatography, mass spectrometry, and molecular networking approaches proved to be a powerful tool for the metabolomic study of GSFR. This study showed metabolomics differences of protective substances in the roots, evidencing a quick response of the plant to the attack of A. besseyi.

Transcriptome-Based Analysis Reveals a Crucial Role of BxGPCR17454 in Low Temperature Response of Pine Wood Nematode (Bursaphelenchus xylophilus)

Background: The causal agent of pine wilt disease is the pine wood nematode (PWN) (Bursaphelenchus xylophilus), whose ability to adapt different ecological niches is a crucial determinant of their invasion to colder regions. To discover the molecular mechanism of low temperature response mechanism, we attempted to study the molecular response patterns under low temperature from B. xylophilus with a comprehensive RNA sequencing analysis and validated the differentially expressed genes (DEGs) with quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatic software was utilized to isolate and identify the low-temperature-related BxGPCR genes. Transcript abundance of six low-temperature-related BxGPCR genes and function of one of the BxGPCR genes are studied by qRT-PCR and RNA interference. Results: The results showed that we detected 432 DEGs through RNA sequencing between low-temperature-treated and ambient-temperature-treated groups nematodes. The transcript level of 6 low-temperature-related BxGPCR genes increased at low temperature. And, the survival rates of BxGPCR17454 silenced B. xylophilus revealed a significant decrease at low temperature. Conclusion: in conclusion, this transcriptome-based study revealed a crucial role of BxGPCR17454 in low temperature response process of pine wood nematode. These discoveries would assist the development of management and methods for efficient control of this devastating pine tree pest.